diff --git a/docs/.gitignore b/docs/.gitignore index 33d25238..075b2542 100644 --- a/docs/.gitignore +++ b/docs/.gitignore @@ -1,26 +1 @@ -.quarto -_site - -*.ddb - -site_libs - -*.csv -*.parquet -*.delta -*.zip -*.db -diamonds.json -*.ndjson -reference/ -objects.json - -# generated notebooks and files -*.ipynb -*_files - -# inventories -_inv -objects.txt - /.quarto/ diff --git a/docs/README.md b/docs/README.md new file mode 100644 index 00000000..a0e77169 --- /dev/null +++ b/docs/README.md @@ -0,0 +1,32 @@ +# Mintlify Starter Kit + +Click on `Use this template` to copy the Mintlify starter kit. The starter kit contains examples including + +- Guide pages +- Navigation +- Customizations +- API Reference pages +- Use of popular components + +### Development + +Install the [Mintlify CLI](https://www.npmjs.com/package/mintlify) to preview the documentation changes locally. To install, use the following command + +``` +npm i -g mintlify +``` + +Run the following command at the root of your documentation (where docs.json is) + +``` +mintlify dev +``` + +### Publishing Changes + +Install our Github App to auto propagate changes from your repo to your deployment. Changes will be deployed to production automatically after pushing to the default branch. Find the link to install on your dashboard. + +#### Troubleshooting + +- Mintlify dev isn't running - Run `mintlify install` it'll re-install dependencies. +- Page loads as a 404 - Make sure you are running in a folder with `docs.json` diff --git a/docs/_publish.yml b/docs/_publish.yml deleted file mode 100644 index 497c77dd..00000000 --- a/docs/_publish.yml +++ /dev/null @@ -1,4 +0,0 @@ -- source: project - netlify: - - id: a62c5e9d-345a-4ae1-8328-5dce211f0661 - url: 'https://letsql-docs.netlify.app' diff --git a/docs/_quarto.yml b/docs/_quarto.yml index 7dc8d6c0..1d679b23 100644 --- a/docs/_quarto.yml +++ b/docs/_quarto.yml @@ -74,11 +74,10 @@ format: include-in-header: "style/fontawesome.html" quartodoc: - package: ibis + package: letsql title: Reference sidebar: reference/_sidebar.yml render_interlinks: true - renderer: _renderer.py options: signature_name: short sections: @@ -90,7 +89,7 @@ quartodoc: summary: name: Table expressions desc: Tables are one of the core data structures in Ibis. - package: ibis.expr.types.relations + package: letsql.vendor.ibis.expr.types.relations contents: - name: Table members: @@ -110,10 +109,12 @@ quartodoc: - sql - union - view + - cache + - into_backend - kind: page path: expression-generic - package: ibis.expr.types.generic + package: letsql.vendor.ibis.expr.types.generic summary: name: Generic expressions desc: Scalars and columns of any element type. @@ -152,7 +153,7 @@ quartodoc: - kind: page path: expression-numeric - package: ibis.expr.types.numeric + package: letsql.vendor.ibis.expr.types.numeric summary: name: Numeric and Boolean expressions desc: Integer, floating point, decimal, and boolean expressions. @@ -201,7 +202,7 @@ quartodoc: - kind: page path: expression-strings - package: ibis.expr.types.strings + package: letsql.vendor.ibis.expr.types.strings summary: name: String expressions desc: All string operations are valid for both scalars and columns. @@ -247,7 +248,7 @@ quartodoc: - kind: page path: expression-temporal - package: ibis.expr.types.temporal + package: letsql.vendor.ibis.expr.types.temporal summary: name: Temporal expressions desc: Dates, times, timestamps and intervals. @@ -281,4 +282,63 @@ quartodoc: - truncate - name: IntervalValue members: - - to_unit \ No newline at end of file + - to_unit + + - kind: page + path: toplevel-api + package: letsql.expr.api + summary: + name: Top Level API functions + contents: + - param + - schema + - table + - memtable + - desc + - asc + - preceding + - following + - and_ + - or_ + - random + - uuid + - case + - now + - today + - rank + - dense_rank + - percent_rank + - cume_dist + - ntile + - row_number + - read_csv + - read_parquet + - register + - read_postgres + - read_sqlite + - union + - intersect + - difference + - ifelse + - coalesce + - greatest + - least + - range + - timestamp + - date + - time + - interval + - to_sql + - execute + - to_pyarrow_batches + - to_pyarrow + - to_parquet + - get_plans + + - kind: page + path: ml-api + package: letsql.expr.ml + summary: + name: ML API functions + contents: + - train_test_splits \ No newline at end of file diff --git a/docs/_renderer.py b/docs/_renderer.py deleted file mode 100644 index 10544b7a..00000000 --- a/docs/_renderer.py +++ /dev/null @@ -1,96 +0,0 @@ -from __future__ import annotations - -from textwrap import dedent - -import quartodoc as qd -import toolz -from plum import dispatch - - -class Renderer(qd.MdRenderer): - style = "ibis" - - @dispatch - def render(self, el: qd.ast.ExampleCode) -> str: - doc = el.value.replace("ibis.examples", "letsql.examples").replace( - 'x.cast("uint16")', 'x.cast("int8")' - ) - lines = doc.splitlines() - - result = [] - - prompt = ">>> " - continuation = "..." - - skip_doctest = "doctest: +SKIP" - expect_failure = "quartodoc: +EXPECTED_FAILURE" - quartodoc_skip_doctest = "quartodoc: +SKIP" - - def chunker(line): - return line.startswith((prompt, continuation)) - - def should_skip(line): - return quartodoc_skip_doctest in line or skip_doctest in line - - for chunk in toolz.partitionby(chunker, lines): - first, *rest = chunk - - # only attempt to execute or render code blocks that start with the - # >>> prompt - if first.startswith(prompt): - # check whether to skip execution and if so, render the code - # block as `python` (not `{python}`) if it's marked with - # skip_doctest, expect_failure or quartodoc_skip_doctest - if skipped := any(map(should_skip, chunk)): - start = end = "" - else: - start, end = "{}" - result.append( - dedent( - """ - ```{python} - #| echo: false - - import letsql - import ibis - ibis.options.interactive = True - ``` - """ - ) - ) - - result.append(f"```{start}python{end}") - - # if we expect failures, don't fail the notebook execution and - # render the error message - if expect_failure in first or any( - expect_failure in line for line in rest - ): - assert start and end, ( - "expected failure should never occur alongside a skipped doctest example" - ) - result.append("#| error: true") - - # remove the quartodoc markers from the rendered code - result.append( - first.replace(f"# {quartodoc_skip_doctest}", "") - .replace(quartodoc_skip_doctest, "") - .replace(f"# {expect_failure}", "") - .replace(expect_failure, "") - ) - result.extend(rest) - result.append("```\n") - - if not skipped: - result.append( - dedent( - """ - ```{python} - #| echo: false - ibis.options.interactive = False - ``` - """ - ) - ) - - return "\n".join(result) diff --git a/docs/_supported.py b/docs/_supported.py index 9236e8f7..e69de29b 100644 --- a/docs/_supported.py +++ b/docs/_supported.py @@ -1,160 +0,0 @@ -"""This file is used to generate the Ibis API Expression implemented by LETSQL""" - -from __future__ import annotations - -import inspect -import re -from collections import defaultdict - -import ibis.expr.operations as ops -import yaml -from ibis.backends.sql.compilers.base import ALL_OPERATIONS -from ibis.expr.types.arrays import ArrayValue -from ibis.expr.types.binary import BinaryValue -from ibis.expr.types.collections import SetValue -from ibis.expr.types.core import Expr -from ibis.expr.types.generic import Column, Scalar, Value -from ibis.expr.types.geospatial import GeoSpatialValue -from ibis.expr.types.inet import INETValue, MACADDRValue -from ibis.expr.types.joins import Join -from ibis.expr.types.json import JSONValue -from ibis.expr.types.logical import BooleanColumn, BooleanValue -from ibis.expr.types.maps import MapValue -from ibis.expr.types.numeric import ( - DecimalColumn, - FloatingColumn, - IntegerColumn, - NumericColumn, -) -from ibis.expr.types.relations import Table -from ibis.expr.types.strings import StringValue -from ibis.expr.types.structs import StructValue -from ibis.expr.types.temporal import ( - DateValue, - DayOfWeek, - IntervalValue, - TimestampValue, - TimeValue, -) -from ibis.expr.types.uuid import UUIDValue - -from xorq.backends.let import Backend as LETSQLBackend - - -support_matrix_ignored_operations = (ops.ScalarParameter,) - -public_ops = ALL_OPERATIONS.difference(support_matrix_ignored_operations) - -letsql_ops = {op.__name__ for op in public_ops if LETSQLBackend.has_operation(op)} - -values = [ - ArrayValue, - BinaryValue, - SetValue, - Expr, - Value, - Scalar, - GeoSpatialValue, - MACADDRValue, - INETValue, - JSONValue, - BooleanValue, - BooleanColumn, - MapValue, - NumericColumn, - IntegerColumn, - FloatingColumn, - DecimalColumn, - Table, - Join, - StringValue, - StructValue, - TimeValue, - DateValue, - Column, - DayOfWeek, - TimestampValue, - IntervalValue, - UUIDValue, -] - -matching_result = {} -immediate = re.compile(r"return (_binop\()?ops\.(\w+)") -saving = re.compile(r"(node|op) = ops\.(\w+)") -node_ret = re.compile(r"return (_binop\()?(node|op)") - -groups = defaultdict(list) -for value in values: - if hasattr(value, "__module__"): - groups[value.__module__].append(value) - else: - groups[value.__name__].append(value) - - -def order_key(v, order=None): - if order is None: - order = [ - "relations", - "joins", - "generic", - "numeric", - "strings", - "temporal", - "collections", - "geospatial", - "json", - "maps", - "uuid", - ] - module_name = v.split(".")[-1] - return order.index(module_name) if module_name in order else len(order) - - -def extract_members(class_value, implemented_ops): - class_members = set() - for m in dir(class_value): - at = getattr(class_value, m) - if inspect.isfunction(at) and not at.__name__.startswith("__"): - source_code = inspect.getsource(at) - matches = list(immediate.finditer(source_code)) - for match in matches: - if match: - op = match.groups()[-1] - if op in implemented_ops: - implemented_ops.remove(op) - class_members.add(at.__name__) - - if not matches: - if node_ret.search(source_code) and ( - matches := list(saving.finditer(source_code)) - ): - for match in matches: - if match: - op = match.groups()[-1] - if op in implemented_ops: - implemented_ops.remove(op) - class_members.add(at.__name__) - return sorted(class_members) - - -pages = [] -for key in sorted(groups, key=order_key): - first = True - page = {} - for value in groups[key]: - members = extract_members(value, letsql_ops) - if members: - if first: - path = key.split(".")[-1] - page = { - "kind": "page", - "path": f"expression-{path}", - "package": key, - "contents": [], - } - first = False - page["contents"].append({"name": value.__name__, "members": members}) - if "contents" in page and page["contents"]: - pages.append(page) - -print(yaml.dump(pages, sort_keys=False)) diff --git a/docs/api-reference.qmd b/docs/api-reference.qmd deleted file mode 100644 index 54cde867..00000000 --- a/docs/api-reference.qmd +++ /dev/null @@ -1,3 +0,0 @@ -# API Reference - -The Backend and Expression API are built on top of Ibis; here, we reproduce only the methods and functions implemented by LETSQL. \ No newline at end of file diff --git a/docs/api-reference/expression-generic.mdx b/docs/api-reference/expression-generic.mdx new file mode 100644 index 00000000..d81d2a42 --- /dev/null +++ b/docs/api-reference/expression-generic.mdx @@ -0,0 +1,1213 @@ +--- +title: 'Generic expressions' +--- + +Scalars and columns of any element type. + +# Value + +```python +Value(self, arg) +``` + +Base class for a data generating expression having a known type. + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [asc](#letsql.vendor.ibis.expr.types.generic.Value.asc) | Sort an expression ascending. | +| [cast](#letsql.vendor.ibis.expr.types.generic.Value.cast) | Cast expression to indicated data type. | +| [coalesce](#letsql.vendor.ibis.expr.types.generic.Value.coalesce) | Return the first non-null value from `args`. | +| [collect](#letsql.vendor.ibis.expr.types.generic.Value.collect) | Aggregate this expression’s elements into an array. | +| [identical_to](#letsql.vendor.ibis.expr.types.generic.Value.identical_to) | Return whether this expression is identical to other. | +| [isin](#letsql.vendor.ibis.expr.types.generic.Value.isin) | Check whether this expression’s values are in `values`. | +| [isnull](#letsql.vendor.ibis.expr.types.generic.Value.isnull) | Return whether this expression is NULL. | +| [name](#letsql.vendor.ibis.expr.types.generic.Value.name) | Rename an expression to `name`. | +| [notnull](#letsql.vendor.ibis.expr.types.generic.Value.notnull) | Return whether this expression is not NULL. | +| [nullif](#letsql.vendor.ibis.expr.types.generic.Value.nullif) | Set values to null if they equal the values `null_if_expr`. | +| [try_cast](#letsql.vendor.ibis.expr.types.generic.Value.try_cast) | Try cast expression to indicated data type. | + +### asc + +```python +asc(nulls_first=False) +``` + +Sort an expression ascending. + +### cast + +```python +cast(target_type) +``` + +Cast expression to indicated data type. + +Similar to `pandas.Series.astype`. + +#### Parameters + +| Name | Type | Description | Default | +|--------|------------|---------------------------------------------|--------| +| target_type | [Any](%60typing.Any%60) | Type to cast to. Anything accepted by [`ibis.dtype()`](./datatypes.qmd#ibis.dtype) | *required* | + +#### Returns + +| Name | Type | Description | +|--------|-----------------------------------------------|-----------------| +| | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) | Casted expression | + +#### See Also + +[`Value.try_cast()`](./expression-generic.qmd#ibis.expr.types.generic.Value.try_cast) +[`ibis.dtype()`](./datatypes.qmd#ibis.dtype) + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> x = ibis.examples.penguins.fetch()["bill_depth_mm"] +>>> x +┏━━━━━━━━━━━━━━━┓ +┃ bill_depth_mm ┃ +┡━━━━━━━━━━━━━━━┩ +│ float64 │ +├───────────────┤ +│ 18.7 │ +│ 17.4 │ +│ 18.0 │ +│ NULL │ +│ 19.3 │ +│ 20.6 │ +│ 17.8 │ +│ 19.6 │ +│ 18.1 │ +│ 20.2 │ +│ … │ +└───────────────┘ +``` + +python’s built-in types can be used + +```python +>>> x.cast(int) +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ Cast(bill_depth_mm, int64) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ +├────────────────────────────┤ +│ 19 │ +│ 17 │ +│ 18 │ +│ NULL │ +│ 19 │ +│ 21 │ +│ 18 │ +│ 20 │ +│ 18 │ +│ 20 │ +│ … │ +└────────────────────────────┘ +``` + +or string names + +```python +>>> x.cast("uint16") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ Cast(bill_depth_mm, uint16) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ uint16 │ +├─────────────────────────────┤ +│ 19 │ +│ 17 │ +│ 18 │ +│ NULL │ +│ 19 │ +│ 21 │ +│ 18 │ +│ 20 │ +│ 18 │ +│ 20 │ +│ … │ +└─────────────────────────────┘ +``` + +If you make an illegal cast, you won’t know until the backend actually +executes it. Consider +[`.try_cast()`](#ibis.expr.types.generic.Value.try_cast). + +```python +>>> ibis.literal("a string").cast("int64") + +``` + +### coalesce + +```python +coalesce(*args) +``` + +Return the first non-null value from `args`. + +#### Parameters + +| Name | Type | Description | Default | +|------|------------------------------|------------------------------|-------| +| args | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) | Arguments from which to choose the first non-null value | `()` | + +#### Returns + +| Name | Type | Description | +|--------|----------------------------------------------|-------------------| +| | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) | Coalesced expression | + +#### See Also + +[`ibis.coalesce()`](./expression-generic.qmd#ibis.coalesce) +[`Value.fill_null()`](./expression-generic.qmd#ibis.expr.types.generic.Value.fill_null) + +#### Examples + +```python +>>> import ibis +>>> ibis.coalesce(None, 4, 5).name("x") +x: Coalesce(...) +``` + +### collect + +```python +collect(where=None, order_by=None, include_null=False) +``` + +Aggregate this expression’s elements into an array. + +This function is called `array_agg`, `list_agg`, or `list` in other +systems. + +#### Parameters + +| Name | Type | Description | Default | +|-----|--------------------------|--------------------------------------|----| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | An optional filter expression. If provided, only rows where `where` is `True` will be included in the aggregate. | `None` | +| order_by | [Any](%60typing.Any%60) | An ordering key (or keys) to use to order the rows before aggregating. If not provided, the order of the items in the result is undefined and backend specific. | `None` | +| include_null | [bool](%60bool%60) | Whether to include null values when performing this aggregation. Set to `True` to include nulls in the result. | `False` | + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|--------------| +| | [ArrayScalar](%60letsql.vendor.ibis.expr.types.arrays.ArrayScalar%60) | Collected array | + +#### Examples + +Basic collect usage + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"key": list("aaabb"), "value": [1, 2, 3, 4, 5]}) +>>> t +┏━━━━━━━━┳━━━━━━━┓ +┃ key ┃ value ┃ +┡━━━━━━━━╇━━━━━━━┩ +│ string │ int64 │ +├────────┼───────┤ +│ a │ 1 │ +│ a │ 2 │ +│ a │ 3 │ +│ b │ 4 │ +│ b │ 5 │ +└────────┴───────┘ +>>> t.value.collect() +┌────────────────┐ +│ [1, 2, ... +3] │ +└────────────────┘ +>>> type(t.value.collect()) + +``` + +Collect elements per group + +```python +>>> t.group_by("key").agg(v=lambda t: t.value.collect()).order_by("key") +┏━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━┓ +┃ key ┃ v ┃ +┡━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ array │ +├────────┼──────────────────────┤ +│ a │ [1, 2, ... +1] │ +│ b │ [4, 5] │ +└────────┴──────────────────────┘ +``` + +Collect elements per group using a filter + +```python +>>> t.group_by("key").agg(v=lambda t: t.value.collect(where=t.value > 1)).order_by("key") +┏━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━┓ +┃ key ┃ v ┃ +┡━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ array │ +├────────┼──────────────────────┤ +│ a │ [2, 3] │ +│ b │ [4, 5] │ +└────────┴──────────────────────┘ +``` + +### identical_to + +```python +identical_to(other) +``` + +Return whether this expression is identical to other. + +Corresponds to `IS NOT DISTINCT FROM` in SQL. + +#### Parameters + +| Name | Type | Description | Default | +|-------|--------------------------------------|-------------------|---------| +| other | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) | Expression to compare to | *required* | + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------|-----------------------------| +| | [BooleanValue](%60letsql.vendor.ibis.expr.types.logical.BooleanValue%60) | Whether this expression is not distinct from `other` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> one = ibis.literal(1) +>>> two = ibis.literal(2) +>>> two.identical_to(one + one) +┌──────┐ +│ True │ +└──────┘ +``` + +### isin + +```python +isin(values) +``` + +Check whether this expression’s values are in `values`. + +`NULL` values are propagated in the output. See examples for details. + +#### Parameters + +| Name | Type | Description | Default | +|----|-------------------------------------------------|---------------|-----| +| values | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) \| [Sequence](%60collections.abc.Sequence%60)\[[Value](%60letsql.vendor.ibis.expr.types.generic.Value%60)\] | Values or expression to check for membership | *required* | + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------------|----------------------| +| | [BooleanValue](%60letsql.vendor.ibis.expr.types.logical.BooleanValue%60) | Expression indicating membership | + +#### See Also + +[`Value.notin()`](./expression-generic.qmd#ibis.expr.types.generic.Value.notin) + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"a": [1, 2, 3], "b": [2, 3, 4]}) +>>> t +┏━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━┩ +│ int64 │ int64 │ +├───────┼───────┤ +│ 1 │ 2 │ +│ 2 │ 3 │ +│ 3 │ 4 │ +└───────┴───────┘ +``` + +Check against a literal sequence of values + +```python +>>> t.a.isin([1, 2]) +┏━━━━━━━━━━━━━━━━━━━━━┓ +┃ InValues(a, (1, 2)) ┃ +┡━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├─────────────────────┤ +│ True │ +│ True │ +│ False │ +└─────────────────────┘ +``` + +Check against a derived expression + +```python +>>> t.a.isin(t.b + 1) +┏━━━━━━━━━━━━━━━┓ +┃ InSubquery(a) ┃ +┡━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────┤ +│ False │ +│ False │ +│ True │ +└───────────────┘ +``` + +Check against a column from a different table + +```python +>>> t2 = ibis.memtable({"x": [99, 2, 99]}) +>>> t.a.isin(t2.x) +┏━━━━━━━━━━━━━━━┓ +┃ InSubquery(a) ┃ +┡━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────┤ +│ False │ +│ True │ +│ False │ +└───────────────┘ +``` + +`NULL` behavior + +```python +>>> t = ibis.memtable({"x": [1, 2]}) +>>> t.x.isin([1, None]) +┏━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ InValues(x, (1, None)) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├────────────────────────┤ +│ True │ +│ NULL │ +└────────────────────────┘ +>>> t = ibis.memtable({"x": [1, None, 2]}) +>>> t.x.isin([1]) +┏━━━━━━━━━━━━━━━━━━━┓ +┃ InValues(x, (1,)) ┃ +┡━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────────┤ +│ True │ +│ NULL │ +│ False │ +└───────────────────┘ +>>> t.x.isin([3]) +┏━━━━━━━━━━━━━━━━━━━┓ +┃ InValues(x, (3,)) ┃ +┡━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────────┤ +│ False │ +│ NULL │ +│ False │ +└───────────────────┘ +``` + +### isnull + +```python +isnull() +``` + +Return whether this expression is NULL. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch().limit(5) +>>> t.bill_depth_mm +┏━━━━━━━━━━━━━━━┓ +┃ bill_depth_mm ┃ +┡━━━━━━━━━━━━━━━┩ +│ float64 │ +├───────────────┤ +│ 18.7 │ +│ 17.4 │ +│ 18.0 │ +│ NULL │ +│ 19.3 │ +└───────────────┘ +>>> t.bill_depth_mm.isnull() +┏━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ IsNull(bill_depth_mm) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────────────┤ +│ False │ +│ False │ +│ False │ +│ True │ +│ False │ +└───────────────────────┘ +``` + +### name + +```python +name(name) +``` + +Rename an expression to `name`. + +#### Parameters + +| Name | Type | Description | Default | +|------|------|--------------------------------|------------| +| name | | The new name of the expression | *required* | + +#### Returns + +| Name | Type | Description | +|--------|--------------------------------------------|---------------------| +| | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) | `self` with name `name` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"a": [1, 2]}, name="t") +>>> t.a +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t.a.name("b") +┏━━━━━━━┓ +┃ b ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +``` + +### notnull + +```python +notnull() +``` + +Return whether this expression is not NULL. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch().limit(5) +>>> t.bill_depth_mm +┏━━━━━━━━━━━━━━━┓ +┃ bill_depth_mm ┃ +┡━━━━━━━━━━━━━━━┩ +│ float64 │ +├───────────────┤ +│ 18.7 │ +│ 17.4 │ +│ 18.0 │ +│ NULL │ +│ 19.3 │ +└───────────────┘ +>>> t.bill_depth_mm.notnull() +┏━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ NotNull(bill_depth_mm) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├────────────────────────┤ +│ True │ +│ True │ +│ True │ +│ False │ +│ True │ +└────────────────────────┘ +``` + +### nullif + +```python +nullif(null_if_expr) +``` + +Set values to null if they equal the values `null_if_expr`. + +Commonly used to avoid divide-by-zero problems by replacing zero with +`NULL` in the divisor. + +Equivalent to `(self == null_if_expr).ifelse(ibis.null(), self)`. + +#### Parameters + +| Name | Type | Description | Default | +|---------|------------------------------|---------------------------|--------| +| null_if_expr | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) | Expression indicating what values should be NULL | *required* | + +#### Returns + +| Name | Type | Description | +|--------|------------------------------------------------|----------------| +| | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) | Value expression | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> vals = ibis.examples.penguins.fetch().head(5).sex +>>> vals +┏━━━━━━━━┓ +┃ sex ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ male │ +│ female │ +│ female │ +│ NULL │ +│ female │ +└────────┘ +>>> vals.nullif("male") +┏━━━━━━━━━━━━━━━━━━━━━┓ +┃ NullIf(sex, 'male') ┃ +┡━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────────┤ +│ NULL │ +│ female │ +│ female │ +│ NULL │ +│ female │ +└─────────────────────┘ +``` + +### try_cast + +```python +try_cast(target_type) +``` + +Try cast expression to indicated data type. + +If the cast fails for a row, the value is returned as null or NaN +depending on target_type and backend behavior. + +#### Parameters + +| Name | Type | Description | Default | +|--------|------------|----------------------------------------------|--------| +| target_type | [Any](%60typing.Any%60) | Type to try cast to. Anything accepted by [`ibis.dtype()`](./datatypes.qmd#ibis.dtype) | *required* | + +#### Returns + +| Name | Type | Description | +|--------|-----------------------------------------------|-----------------| +| | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) | Casted expression | + +#### See Also + +[`Value.cast()`](./expression-generic.qmd#ibis.expr.types.generic.Value.cast) +[`ibis.dtype()`](./datatypes.qmd#ibis.dtype) + +#### Examples + +```python +>>> import ibis +>>> from letsql.vendor.ibis import _ +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"numbers": [1, 2, 3, 4], "strings": ["1.0", "2", "hello", "world"]}) +>>> t +┏━━━━━━━━━┳━━━━━━━━━┓ +┃ numbers ┃ strings ┃ +┡━━━━━━━━━╇━━━━━━━━━┩ +│ int64 │ string │ +├─────────┼─────────┤ +│ 1 │ 1.0 │ +│ 2 │ 2 │ +│ 3 │ hello │ +│ 4 │ world │ +└─────────┴─────────┘ +>>> t = t.mutate(numbers_to_strings=_.numbers.try_cast("string")) +>>> t = t.mutate(strings_to_numbers=_.strings.try_cast("int")) +>>> t +┏━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━┓ +┃ numbers ┃ strings ┃ numbers_to_strings ┃ strings_to_numbers ┃ +┡━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ string │ string │ int64 │ +├─────────┼─────────┼────────────────────┼────────────────────┤ +│ 1 │ 1.0 │ 1 │ 1 │ +│ 2 │ 2 │ 2 │ 2 │ +│ 3 │ hello │ 3 │ NULL │ +│ 4 │ world │ 4 │ NULL │ +└─────────┴─────────┴────────────────────┴────────────────────┘ +``` + +# Scalar + +```python +Scalar(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [as_table](#letsql.vendor.ibis.expr.types.generic.Scalar.as_table) | Promote the scalar expression to a table. | + +### as_table + +```python +as_table() +``` + +Promote the scalar expression to a table. + +#### Returns + +| Name | Type | Description | +|--------|----------------------------------------------|------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.joins.Table%60) | A table expression | + +#### Examples + +Promote an aggregation to a table + +```python +>>> import ibis +>>> import ibis.expr.types as ir +>>> t = ibis.table(dict(a="str"), name="t") +>>> expr = t.a.length().sum().name("len").as_table() +>>> isinstance(expr, ir.Table) +True +``` + +Promote a literal value to a table + +```python +>>> import ibis.expr.types as ir +>>> lit = ibis.literal(1).name("a").as_table() +>>> isinstance(lit, ir.Table) +True +``` + +# Column + +```python +Column(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [approx_median](#letsql.vendor.ibis.expr.types.generic.Column.approx_median) | Return an approximate of the median of `self`. | +| [approx_nunique](#letsql.vendor.ibis.expr.types.generic.Column.approx_nunique) | Return the approximate number of distinct elements in `self`. | +| [arbitrary](#letsql.vendor.ibis.expr.types.generic.Column.arbitrary) | Select an arbitrary value in a column. | +| [count](#letsql.vendor.ibis.expr.types.generic.Column.count) | Compute the number of rows in an expression. | +| [first](#letsql.vendor.ibis.expr.types.generic.Column.first) | Return the first value of a column. | +| [lag](#letsql.vendor.ibis.expr.types.generic.Column.lag) | Return the row located at `offset` rows **before** the current row. | +| [last](#letsql.vendor.ibis.expr.types.generic.Column.last) | Return the last value of a column. | +| [lead](#letsql.vendor.ibis.expr.types.generic.Column.lead) | Return the row located at `offset` rows **after** the current row. | +| [max](#letsql.vendor.ibis.expr.types.generic.Column.max) | Return the maximum of a column. | +| [median](#letsql.vendor.ibis.expr.types.generic.Column.median) | Return the median of the column. | +| [min](#letsql.vendor.ibis.expr.types.generic.Column.min) | Return the minimum of a column. | +| [nth](#letsql.vendor.ibis.expr.types.generic.Column.nth) | Return the `n`th value (0-indexed) over a window. | +| [nunique](#letsql.vendor.ibis.expr.types.generic.Column.nunique) | Compute the number of distinct rows in an expression. | + +### approx_median + +```python +approx_median(where=None) +``` + +Return an approximate of the median of `self`. + + + The result may or may not be exact. Whether the result is an approximation depends on the backend. + + + + + + Do not depend on the results being exact + + +#### Parameters + +| Name | Type | Description | Default | +|-----|---------------------------------------------|------------------|------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter in values when `where` is `True` | `None` | + +#### Returns + +| Name | Type | Description | +|-------|--------------------------------------|----------------------------| +| | [Scalar](%60letsql.vendor.ibis.expr.types.generic.Scalar%60) | An approximation of the median of `self` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.approx_median() +┌────────┐ +│ 4030.0 │ +└────────┘ +>>> t.body_mass_g.approx_median(where=t.species == "Chinstrap") +┌────────┐ +│ 3700.0 │ +└────────┘ +``` + +### approx_nunique + +```python +approx_nunique(where=None) +``` + +Return the approximate number of distinct elements in `self`. + + +The result may or may not be exact. Whether the result is an approximation depends on the backend. + + + +Do not depend on the results being exact + + +#### Parameters + +| Name | Type | Description | Default | +|-----|---------------------------------------------|------------------|------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter in values when `where` is `True` | `None` | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------|---------------------------------| +| | [Scalar](%60letsql.vendor.ibis.expr.types.generic.Scalar%60) | An approximate count of the distinct elements of `self` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.approx_nunique() +┌────┐ +│ 92 │ +└────┘ +>>> t.body_mass_g.approx_nunique(where=t.species == "Adelie") +┌────┐ +│ 61 │ +└────┘ +``` + +### arbitrary + +```python +arbitrary(where=None, how=None) +``` + +Select an arbitrary value in a column. + +Returns an arbitrary (nondeterministic, backend-specific) value from the +column. The value will be non-NULL, except if the column is empty or all +values are NULL. + +#### Parameters + +| Name | Type | Description | Default | +|-----|--------------------------------------------------|-----------|------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | A filter expression | `None` | +| how | [Any](%60typing.Any%60) | DEPRECATED | `None` | + +#### Returns + +| Name | Type | Description | +|--------|--------------------------------------------------|--------------| +| | [Scalar](%60letsql.vendor.ibis.expr.types.generic.Scalar%60) | An expression | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"a": [1, 2, 2], "b": list("aaa"), "c": [4.0, 4.1, 4.2]}) +>>> t +┏━━━━━━━┳━━━━━━━━┳━━━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━━━┩ +│ int64 │ string │ float64 │ +├───────┼────────┼─────────┤ +│ 1 │ a │ 4.0 │ +│ 2 │ a │ 4.1 │ +│ 2 │ a │ 4.2 │ +└───────┴────────┴─────────┘ +>>> t.group_by("a").agg(arb=t.b.arbitrary(), c=t.c.sum()).order_by("a") +┏━━━━━━━┳━━━━━━━━┳━━━━━━━━━┓ +┃ a ┃ arb ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━━━┩ +│ int64 │ string │ float64 │ +├───────┼────────┼─────────┤ +│ 1 │ a │ 4.0 │ +│ 2 │ a │ 8.3 │ +└───────┴────────┴─────────┘ +``` + +### count + +```python +count(where=None) +``` + +Compute the number of rows in an expression. + +#### Parameters + +| Name | Type | Description | Default | +|-----|---------------------------------------------------|----------|-------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter expression | `None` | + +#### Returns + +| Name | Type | Description | +|------|-------------------------------------------|-----------------------| +| | [IntegerScalar](%60letsql.vendor.ibis.expr.types.numeric.IntegerScalar%60) | Number of elements in an expression | + +### first + +```python +first(where=None, order_by=None, include_null=False) +``` + +Return the first value of a column. + +#### Parameters + +| Name | Type | Description | Default | +|-----|---------------------------|--------------------------------------|----| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | An optional filter expression. If provided, only rows where `where` is `True` will be included in the aggregate. | `None` | +| order_by | [Any](%60typing.Any%60) | An ordering key (or keys) to use to order the rows before aggregating. If not provided, the meaning of `first` is undefined and will be backend specific. | `None` | +| include_null | [bool](%60bool%60) | Whether to include null values when performing this aggregation. Set to `True` to include nulls in the result. | `False` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"chars": ["a", "b", "c", "d"]}) +>>> t +┏━━━━━━━━┓ +┃ chars ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ a │ +│ b │ +│ c │ +│ d │ +└────────┘ +>>> t.chars.first() +┌───┐ +│ a │ +└───┘ +>>> t.chars.first(where=t.chars != "a") +┌───┐ +│ b │ +└───┘ +``` + +### lag + +```python +lag(offset=None, default=None) +``` + +Return the row located at `offset` rows **before** the current row. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------------------------------------|----------------|-----| +| offset | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) \| None | Index of row to select | `None` | +| default | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) \| None | Value used if no row exists at `offset` | `None` | + +### last + +```python +last(where=None, order_by=None, include_null=False) +``` + +Return the last value of a column. + +#### Parameters + +| Name | Type | Description | Default | +|-----|---------------------------|-------------------------------------|----| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | An optional filter expression. If provided, only rows where `where` is `True` will be included in the aggregate. | `None` | +| order_by | [Any](%60typing.Any%60) | An ordering key (or keys) to use to order the rows before aggregating. If not provided, the meaning of `last` is undefined and will be backend specific. | `None` | +| include_null | [bool](%60bool%60) | Whether to include null values when performing this aggregation. Set to `True` to include nulls in the result. | `False` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"chars": ["a", "b", "c", "d"]}) +>>> t +┏━━━━━━━━┓ +┃ chars ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ a │ +│ b │ +│ c │ +│ d │ +└────────┘ +>>> t.chars.last() +┌───┐ +│ d │ +└───┘ +>>> t.chars.last(where=t.chars != "d") +┌───┐ +│ c │ +└───┘ +``` + +### lead + +```python +lead(offset=None, default=None) +``` + +Return the row located at `offset` rows **after** the current row. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------------------------------------|----------------|-----| +| offset | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) \| None | Index of row to select | `None` | +| default | [Value](%60letsql.vendor.ibis.expr.types.generic.Value%60) \| None | Value used if no row exists at `offset` | `None` | + +### max + +```python +max(where=None) +``` + +Return the maximum of a column. + +#### Parameters + +| Name | Type | Description | Default | +|-----|---------------------------------------------|------------------|------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter in values when `where` is `True` | `None` | + +#### Returns + +| Name | Type | Description | +|-------|-------------------------------------------|----------------------| +| | [Scalar](%60letsql.vendor.ibis.expr.types.generic.Scalar%60) | The maximum value in `self` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.max() +┌──────┐ +│ 6300 │ +└──────┘ +>>> t.body_mass_g.max(where=t.species == "Chinstrap") +┌──────┐ +│ 4800 │ +└──────┘ +``` + +### median + +```python +median(where=None) +``` + +Return the median of the column. + +#### Parameters + +| Name | Type | Description | Default | +|----|------------------------------|----------------------------------|----| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Optional boolean expression. If given, only the values where `where` evaluates to true will be considered for the median. | `None` | + +#### Returns + +| Name | Type | Description | +|--------|----------------------------------------------|-------------------| +| | [Scalar](%60letsql.vendor.ibis.expr.types.generic.Scalar%60) | Median of the column | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +``` + +Compute the median of `bill_depth_mm` + +```python +>>> t.bill_depth_mm.median() +┌──────┐ +│ 17.3 │ +└──────┘ +>>> t.group_by(t.species).agg(median_bill_depth=t.bill_depth_mm.median()).order_by( +... ibis.desc("median_bill_depth") +... ) +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓ +┃ species ┃ median_bill_depth ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼───────────────────┤ +│ Chinstrap │ 18.45 │ +│ Adelie │ 18.40 │ +│ Gentoo │ 15.00 │ +└───────────┴───────────────────┘ +``` + +In addition to numeric types, any orderable non-numeric types such as +strings and dates work with `median`. + +```python +>>> t.group_by(t.island).agg(median_species=t.species.median()).order_by( +... ibis.desc("median_species") +... ) +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┓ +┃ island ┃ median_species ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━┩ +│ string │ string │ +├───────────┼────────────────┤ +│ Biscoe │ Gentoo │ +│ Dream │ Chinstrap │ +│ Torgersen │ Adelie │ +└───────────┴────────────────┘ +``` + +### min + +```python +min(where=None) +``` + +Return the minimum of a column. + +#### Parameters + +| Name | Type | Description | Default | +|-----|---------------------------------------------|------------------|------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter in values when `where` is `True` | `None` | + +#### Returns + +| Name | Type | Description | +|-------|-------------------------------------------|----------------------| +| | [Scalar](%60letsql.vendor.ibis.expr.types.generic.Scalar%60) | The minimum value in `self` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.min() +┌──────┐ +│ 2700 │ +└──────┘ +>>> t.body_mass_g.min(where=t.species == "Adelie") +┌──────┐ +│ 2850 │ +└──────┘ +``` + +### nth + +```python +nth(n) +``` + +Return the `n`th value (0-indexed) over a window. + +`.nth(0)` is equivalent to `.first()`. Negative will result in `NULL`. +If the value of `n` is greater than the number of rows in the window, +`NULL` will be returned. + +#### Parameters + +| Name | Type | Description | Default | +|-----|---------------------------------------------------|----------|-------| +| n | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) | Desired rank value | *required* | + +#### Returns + +| Name | Type | Description | +|-------|-------------------------------------------|----------------------| +| | [Column](%60letsql.vendor.ibis.expr.types.generic.Column%60) | The nth value over a window | + +### nunique + +```python +nunique(where=None) +``` + +Compute the number of distinct rows in an expression. + +#### Parameters + +| Name | Type | Description | Default | +|-----|---------------------------------------------------|----------|-------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter expression | `None` | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------|--------------------------| +| | [IntegerScalar](%60letsql.vendor.ibis.expr.types.numeric.IntegerScalar%60) | Number of distinct elements in an expression | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.nunique() +┌────┐ +│ 94 │ +└────┘ +>>> t.body_mass_g.nunique(where=t.species == "Adelie") +┌────┐ +│ 55 │ +└────┘ +``` diff --git a/docs/api-reference/expression-numeric.mdx b/docs/api-reference/expression-numeric.mdx new file mode 100644 index 00000000..2c899924 --- /dev/null +++ b/docs/api-reference/expression-numeric.mdx @@ -0,0 +1,938 @@ +--- +title: 'Numeric and Boolean expressions' +--- + +Integer, floating point, decimal, and boolean expressions. + +# NumericColumn + +```python +NumericColumn(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [abs](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.abs) | Return the absolute value of `self`. | +| [acos](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.acos) | Compute the arc cosine of `self`. | +| [asin](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.asin) | Compute the arc sine of `self`. | +| [atan](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.atan) | Compute the arc tangent of `self`. | +| [atan2](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.atan2) | Compute the two-argument version of arc tangent. | +| [bucket](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.bucket) | Compute a discrete binning of a numeric array. | +| [ceil](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.ceil) | Return the ceiling of `self`. | +| [corr](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.corr) | Return the correlation of two numeric columns. | +| [cos](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.cos) | Compute the cosine of `self`. | +| [cot](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.cot) | Compute the cotangent of `self`. | +| [cov](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.cov) | Return the covariance of two numeric columns. | +| [degrees](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.degrees) | Compute the degrees of `self` radians. | +| [exp](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.exp) | Compute $e^\texttt{self}$. | +| [floor](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.floor) | Return the floor of an expression. | +| [ln](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.ln) | Compute $\ln\left(\texttt{self}\right)$. | +| [log](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.log) | Compute $\log_{\texttt{base}}\left(\texttt{self}\right)$. | +| [log10](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.log10) | Compute $\log_{10}\left(\texttt{self}\right)$. | +| [log2](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.log2) | Compute $\log_{2}\left(\texttt{self}\right)$. | +| [mean](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.mean) | Return the mean of a numeric column. | +| [negate](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.negate) | Negate a numeric expression. | +| [radians](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.radians) | Compute radians from `self` degrees. | +| [round](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.round) | Round values to an indicated number of decimal places. | +| [sign](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.sign) | Return the sign of the input. | +| [sin](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.sin) | Compute the sine of `self`. | +| [sqrt](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.sqrt) | Compute the square root of `self`. | +| [std](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.std) | Return the standard deviation of a numeric column. | +| [sum](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.sum) | Return the sum of a numeric column. | +| [tan](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.tan) | Compute the tangent of `self`. | +| [var](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.var) | Return the variance of a numeric column. | + +### abs + +```python +abs() +``` + +Return the absolute value of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 2, -3, 4]}) +>>> t.values.abs() +┏━━━━━━━━━━━━━┓ +┃ Abs(values) ┃ +┡━━━━━━━━━━━━━┩ +│ int64 │ +├─────────────┤ +│ 1 │ +│ 2 │ +│ 3 │ +│ 4 │ +└─────────────┘ +``` + +### acos + +```python +acos() +``` + +Compute the arc cosine of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.acos() +┏━━━━━━━━━━━━━━┓ +┃ Acos(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ 3.141593 │ +│ 1.570796 │ +│ 0.000000 │ +└──────────────┘ +``` + +### asin + +```python +asin() +``` + +Compute the arc sine of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.asin() +┏━━━━━━━━━━━━━━┓ +┃ Asin(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ -1.570796 │ +│ 0.000000 │ +│ 1.570796 │ +└──────────────┘ +``` + +### atan + +```python +atan() +``` + +Compute the arc tangent of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.atan() +┏━━━━━━━━━━━━━━┓ +┃ Atan(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ -0.785398 │ +│ 0.000000 │ +│ 0.785398 │ +└──────────────┘ +``` + +### atan2 + +```python +atan2(other) +``` + +Compute the two-argument version of arc tangent. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.atan2(0) +┏━━━━━━━━━━━━━━━━━━┓ +┃ Atan2(values, 0) ┃ +┡━━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────────┤ +│ -1.570796 │ +│ 0.000000 │ +│ 1.570796 │ +└──────────────────┘ +``` + +### bucket + +```python +bucket( + buckets, + closed='left', + close_extreme=True, + include_under=False, + include_over=False, +) +``` + +Compute a discrete binning of a numeric array. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------|-----------------------------------------------|-----| +| buckets | [Sequence](%60collections.abc.Sequence%60)\[[int](%60int%60)\] | List of buckets | *required* | +| closed | [Literal](%60typing.Literal%60)\['left', 'right'\] | Which side of each interval is closed. For example: `python buckets = [0, 100, 200] closed = "left" # 100 falls in 2nd bucket closed = "right" # 100 falls in 1st bucket` | `'left'` | +| close_extreme | [bool](%60bool%60) | Whether the extreme values fall in the last bucket | `True` | +| include_over | [bool](%60bool%60) | Include values greater than the last bucket in the last bucket | `False` | +| include_under | [bool](%60bool%60) | Include values less than the first bucket in the first bucket | `False` | + +#### Returns + +| Name | Type | Description | +|------|---------------------------------------------|---------------------| +| | [IntegerColumn](%60letsql.vendor.ibis.expr.types.numeric.IntegerColumn%60) | A categorical column expression | + +### ceil + +```python +ceil() +``` + +Return the ceiling of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 1.1, 2, 2.1, 3.3]}) +>>> t.values.ceil() +┏━━━━━━━━━━━━━━┓ +┃ Ceil(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ int64 │ +├──────────────┤ +│ 1 │ +│ 2 │ +│ 2 │ +│ 3 │ +│ 4 │ +└──────────────┘ +``` + +### corr + +```python +corr(right, where=None, how='sample') +``` + +Return the correlation of two numeric columns. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------------------------------------|----------------|------| +| right | [NumericColumn](%60letsql.vendor.ibis.expr.types.numeric.NumericColumn%60) | Numeric column | *required* | +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter | `None` | +| how | [Literal](%60typing.Literal%60)\['sample', 'pop'\] | Population or sample correlation | `'sample'` | + +#### Returns + +| Name | Type | Description | +|------|-------------------------------------------|------------------------| +| | [NumericScalar](%60letsql.vendor.ibis.expr.types.numeric.NumericScalar%60) | The correlation of `left` and `right` | + +### cos + +```python +cos() +``` + +Compute the cosine of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.cos() +┏━━━━━━━━━━━━━┓ +┃ Cos(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ 0.540302 │ +│ 1.000000 │ +│ 0.540302 │ +└─────────────┘ +``` + +### cot + +```python +cot() +``` + +Compute the cotangent of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, -2, 3]}) +>>> t.values.cot() +┏━━━━━━━━━━━━━┓ +┃ Cot(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ -0.642093 │ +│ 0.457658 │ +│ -7.015253 │ +└─────────────┘ +``` + +### cov + +```python +cov(right, where=None, how='sample') +``` + +Return the covariance of two numeric columns. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------------------------------------|---------------|------| +| right | [NumericColumn](%60letsql.vendor.ibis.expr.types.numeric.NumericColumn%60) | Numeric column | *required* | +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter | `None` | +| how | [Literal](%60typing.Literal%60)\['sample', 'pop'\] | Population or sample covariance | `'sample'` | + +#### Returns + +| Name | Type | Description | +|------|-------------------------------------------|-----------------------| +| | [NumericScalar](%60letsql.vendor.ibis.expr.types.numeric.NumericScalar%60) | The covariance of `self` and `right` | + +### degrees + +```python +degrees() +``` + +Compute the degrees of `self` radians. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> from math import pi +>>> t = ibis.memtable({"values": [0, pi / 2, pi, 3 * pi / 2, 2 * pi]}) +>>> t.values.degrees() +┏━━━━━━━━━━━━━━━━━┓ +┃ Degrees(values) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────────┤ +│ 0.0 │ +│ 90.0 │ +│ 180.0 │ +│ 270.0 │ +│ 360.0 │ +└─────────────────┘ +``` + +### exp + +```python +exp() +``` + +Compute $e^\texttt{self}$. + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|---------------| +| | [NumericValue](%60letsql.vendor.ibis.expr.types.numeric.NumericValue%60) | $e^\texttt{self}$ | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": range(4)}) +>>> t.values.exp() +┏━━━━━━━━━━━━━┓ +┃ Exp(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ 1.000000 │ +│ 2.718282 │ +│ 7.389056 │ +│ 20.085537 │ +└─────────────┘ +``` + +### floor + +```python +floor() +``` + +Return the floor of an expression. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 1.1, 2, 2.1, 3.3]}) +>>> t.values.floor() +┏━━━━━━━━━━━━━━━┓ +┃ Floor(values) ┃ +┡━━━━━━━━━━━━━━━┩ +│ int64 │ +├───────────────┤ +│ 1 │ +│ 1 │ +│ 2 │ +│ 2 │ +│ 3 │ +└───────────────┘ +``` + +### ln + +```python +ln() +``` + +Compute $\ln\left(\texttt{self}\right)$. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 2.718281828, 3]}) +>>> t.values.ln() +┏━━━━━━━━━━━━┓ +┃ Ln(values) ┃ +┡━━━━━━━━━━━━┩ +│ float64 │ +├────────────┤ +│ 0.000000 │ +│ 1.000000 │ +│ 1.098612 │ +└────────────┘ +``` + +### log + +```python +log(base=None) +``` + +Compute $\log_{\texttt{base}}\left(\texttt{self}\right)$. + +#### Parameters + +| Name | Type | Description | Default | +|-----|-----------------------------------|--------------------------|------| +| base | [NumericValue](%60letsql.vendor.ibis.expr.types.numeric.NumericValue%60) \| None | The base of the logarithm. If `None`, base `e` is used. | `None` | + +#### Returns + +| Name | Type | Description | +|------|-------------------------------------------|-----------------------| +| | [NumericValue](%60letsql.vendor.ibis.expr.types.numeric.NumericValue%60) | Logarithm of `arg` with base `base` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> from math import e +>>> t = ibis.memtable({"values": [e, e**2, e**3]}) +>>> t.values.log() +┏━━━━━━━━━━━━━┓ +┃ Log(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ 1.0 │ +│ 2.0 │ +│ 3.0 │ +└─────────────┘ +``` + + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [10, 100, 1000]}) +>>> t.values.log(base=10) +┏━━━━━━━━━━━━━━━━━┓ +┃ Log(values, 10) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────────┤ +│ 1.0 │ +│ 2.0 │ +│ 3.0 │ +└─────────────────┘ +``` + +### log10 + +```python +log10() +``` + +Compute $\log_{10}\left(\texttt{self}\right)$. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 10, 100]}) +>>> t.values.log10() +┏━━━━━━━━━━━━━━━┓ +┃ Log10(values) ┃ +┡━━━━━━━━━━━━━━━┩ +│ float64 │ +├───────────────┤ +│ 0.0 │ +│ 1.0 │ +│ 2.0 │ +└───────────────┘ +``` + +### log2 + +```python +log2() +``` + +Compute $\log_{2}\left(\texttt{self}\right)$. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 2, 4, 8]}) +>>> t.values.log2() +┏━━━━━━━━━━━━━━┓ +┃ Log2(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ 0.0 │ +│ 1.0 │ +│ 2.0 │ +│ 3.0 │ +└──────────────┘ +``` + +### mean + +```python +mean(where=None) +``` + +Return the mean of a numeric column. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------------------------------------------|---------|-------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter | `None` | + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------------|----------------------| +| | [NumericScalar](%60letsql.vendor.ibis.expr.types.numeric.NumericScalar%60) | The mean of the input expression | + +### negate + +```python +negate() +``` + +Negate a numeric expression. + +#### Returns + +| Name | Type | Description | +|-------|----------------------------------------------|-------------------| +| | [NumericValue](%60letsql.vendor.ibis.expr.types.numeric.NumericValue%60) | A numeric value expression | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.negate() +┏━━━━━━━━━━━━━━━━┓ +┃ Negate(values) ┃ +┡━━━━━━━━━━━━━━━━┩ +│ int64 │ +├────────────────┤ +│ 1 │ +│ 0 │ +│ -1 │ +└────────────────┘ +``` + +### radians + +```python +radians() +``` + +Compute radians from `self` degrees. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [0, 90, 180, 270, 360]}) +>>> t.values.radians() +┏━━━━━━━━━━━━━━━━━┓ +┃ Radians(values) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────────┤ +│ 0.000000 │ +│ 1.570796 │ +│ 3.141593 │ +│ 4.712389 │ +│ 6.283185 │ +└─────────────────┘ +``` + +### round + +```python +round(digits=None) +``` + +Round values to an indicated number of decimal places. + +#### Parameters + +| Name | Type | Description | Default | +|---|---------------|-----------------------------------------------------|---| +| digits | [int](%60int%60) \| [IntegerValue](%60letsql.vendor.ibis.expr.types.numeric.IntegerValue%60) \| None | The number of digits to round to. Here’s how the `digits` parameter affects the expression output type: - `digits` is `False`-y; `self.type()` is `decimal` → `decimal` - `digits` is nonzero; `self.type()` is `decimal` → `decimal` - `digits` is `False`-y; `self.type()` is Floating → `int64` - `digits` is nonzero; `self.type()` is Floating → `float64` | `None` | + +#### Returns + +| Name | Type | Description | +|-------|------------------------------------------------|------------------| +| | [NumericValue](%60letsql.vendor.ibis.expr.types.numeric.NumericValue%60) | The rounded expression | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1.22, 1.64, 2.15, 2.54]}) +>>> t +┏━━━━━━━━━┓ +┃ values ┃ +┡━━━━━━━━━┩ +│ float64 │ +├─────────┤ +│ 1.22 │ +│ 1.64 │ +│ 2.15 │ +│ 2.54 │ +└─────────┘ +>>> t.values.round() +┏━━━━━━━━━━━━━━━┓ +┃ Round(values) ┃ +┡━━━━━━━━━━━━━━━┩ +│ int64 │ +├───────────────┤ +│ 1 │ +│ 2 │ +│ 2 │ +│ 3 │ +└───────────────┘ +>>> t.values.round(digits=1) +┏━━━━━━━━━━━━━━━━━━┓ +┃ Round(values, 1) ┃ +┡━━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────────┤ +│ 1.2 │ +│ 1.6 │ +│ 2.2 │ +│ 2.5 │ +└──────────────────┘ +``` + +### sign + +```python +sign() +``` + +Return the sign of the input. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 2, -3, 4]}) +>>> t.values.sign() +┏━━━━━━━━━━━━━━┓ +┃ Sign(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ int64 │ +├──────────────┤ +│ -1 │ +│ 1 │ +│ -1 │ +│ 1 │ +└──────────────┘ +``` + +### sin + +```python +sin() +``` + +Compute the sine of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.sin() +┏━━━━━━━━━━━━━┓ +┃ Sin(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ -0.841471 │ +│ 0.000000 │ +│ 0.841471 │ +└─────────────┘ +``` + +### sqrt + +```python +sqrt() +``` + +Compute the square root of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 4, 9, 16]}) +>>> t.values.sqrt() +┏━━━━━━━━━━━━━━┓ +┃ Sqrt(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ 1.0 │ +│ 2.0 │ +│ 3.0 │ +│ 4.0 │ +└──────────────┘ +``` + +### std + +```python +std(where=None, how='sample') +``` + +Return the standard deviation of a numeric column. + +#### Parameters + +| Name | Type | Description | Default | +|-----|--------------------------------------------|------------------|------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter | `None` | +| how | [Literal](%60typing.Literal%60)\['sample', 'pop'\] | Sample or population standard deviation | `'sample'` | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------------|--------------------| +| | [NumericScalar](%60letsql.vendor.ibis.expr.types.numeric.NumericScalar%60) | Standard deviation of `arg` | + +### sum + +```python +sum(where=None) +``` + +Return the sum of a numeric column. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------------------------------------------|---------|-------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter | `None` | + +#### Returns + +| Name | Type | Description | +|------|---------------------------------------------|---------------------| +| | [NumericScalar](%60letsql.vendor.ibis.expr.types.numeric.NumericScalar%60) | The sum of the input expression | + +### tan + +```python +tan() +``` + +Compute the tangent of `self`. + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.tan() +┏━━━━━━━━━━━━━┓ +┃ Tan(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ -1.557408 │ +│ 0.000000 │ +│ 1.557408 │ +└─────────────┘ +``` + +### var + +```python +var(where=None, how='sample') +``` + +Return the variance of a numeric column. + +#### Parameters + +| Name | Type | Description | Default | +|-----|-----------------------------------------------|---------------|-------| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Filter | `None` | +| how | [Literal](%60typing.Literal%60)\['sample', 'pop'\] | Sample or population variance | `'sample'` | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------------|--------------------| +| | [NumericScalar](%60letsql.vendor.ibis.expr.types.numeric.NumericScalar%60) | Standard deviation of `arg` | + +# IntegerColumn + +```python +IntegerColumn(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [bit_and](#letsql.vendor.ibis.expr.types.numeric.IntegerColumn.bit_and) | Aggregate the column using the bitwise and operator. | +| [bit_or](#letsql.vendor.ibis.expr.types.numeric.IntegerColumn.bit_or) | Aggregate the column using the bitwise or operator. | +| [bit_xor](#letsql.vendor.ibis.expr.types.numeric.IntegerColumn.bit_xor) | Aggregate the column using the bitwise exclusive or operator. | +| [to_timestamp](#letsql.vendor.ibis.expr.types.numeric.IntegerColumn.to_timestamp) | | + +### bit_and + +```python +bit_and(where=None) +``` + +Aggregate the column using the bitwise and operator. + +### bit_or + +```python +bit_or(where=None) +``` + +Aggregate the column using the bitwise or operator. + +### bit_xor + +```python +bit_xor(where=None) +``` + +Aggregate the column using the bitwise exclusive or operator. + +### to_timestamp + +```python +to_timestamp(unit='s') +``` + +# FloatingColumn + +```python +FloatingColumn(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [isinf](#letsql.vendor.ibis.expr.types.numeric.FloatingColumn.isinf) | Return whether the value is infinity. | +| [isnan](#letsql.vendor.ibis.expr.types.numeric.FloatingColumn.isnan) | Return whether the value is NaN. | + +### isinf + +```python +isinf() +``` + +Return whether the value is infinity. + +### isnan + +```python +isnan() +``` + +Return whether the value is NaN. diff --git a/docs/api-reference/expression-relations.mdx b/docs/api-reference/expression-relations.mdx new file mode 100644 index 00000000..5e486305 --- /dev/null +++ b/docs/api-reference/expression-relations.mdx @@ -0,0 +1,1420 @@ +--- +title: 'Table expressions' +--- + +Tables are one of the core data structures in Ibis. + +# Table + +```python +Table(self, arg) +``` + +An immutable and lazy dataframe. + +Analogous to a SQL table or a pandas DataFrame. A table expression +contains an [ordered set of named +columns](./schemas.qmd#ibis.expr.schema.Schema), each with a single +known type. Unless explicitly ordered with an +[`.order_by()`](./expression-tables.qmd#letsql.expr.types.relations.Table.order_by), +the order of rows is undefined. + +Table immutability means that the data underlying an Ibis `Table` cannot +be modified: every method on a Table returns a new Table with those +changes. Laziness means that an Ibis `Table` expression does not run +your computation every time you call one of its methods. Instead, it is +a symbolic expression that represents a set of operations to be +performed, which typically is translated into a SQL query. That SQL +query is then executed on a backend, where the data actually lives. The +result (now small enough to be manageable) can then be materialized back +into python as a pandas/pyarrow/python DataFrame/Column/scalar. + +You will not create Table objects directly. Instead, you will create one + +- from a pandas DataFrame, pyarrow table, Polars table, or raw python + dicts/lists with + [`letsql.memtable(df)`](./expression-tables.qmd#letsql.memtable) +- from an existing table in a data platform with + [`connection.table("name")`](./expression-tables.qmd#letsql.backends.duckdb.Backend.table) +- from a file or URL, into a specific backend with + [`connection.read_csv/parquet/json("path/to/file")`](../backends/duckdb.qmd#letsql.backends.duckdb.Backend.read_csv) + (only some backends, typically local ones, support this) +- from a file or URL, into the default backend with + [`ibis.read_csv/read_json/read_parquet("path/to/file")`](./expression-tables.qmd#ibis.read_csv) + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [alias](#letsql.vendor.ibis.expr.types.relations.Table.alias) | Create a table expression with a specific name `alias`. | +| [as_scalar](#letsql.vendor.ibis.expr.types.relations.Table.as_scalar) | Inform ibis that the table expression should be treated as a scalar. | +| [count](#letsql.vendor.ibis.expr.types.relations.Table.count) | Compute the number of rows in the table. | +| [difference](#letsql.vendor.ibis.expr.types.relations.Table.difference) | Compute the set difference of multiple table expressions. | +| [distinct](#letsql.vendor.ibis.expr.types.relations.Table.distinct) | Return a Table with duplicate rows removed. | +| [dropna](#letsql.vendor.ibis.expr.types.relations.Table.dropna) | Deprecated - use `drop_null` instead. | +| [fillna](#letsql.vendor.ibis.expr.types.relations.Table.fillna) | Deprecated - use `fill_null` instead. | +| [filter](#letsql.vendor.ibis.expr.types.relations.Table.filter) | Select rows from `table` based on `predicates`. | +| [intersect](#letsql.vendor.ibis.expr.types.relations.Table.intersect) | Compute the set intersection of multiple table expressions. | +| [limit](#letsql.vendor.ibis.expr.types.relations.Table.limit) | Select `n` rows from `self` starting at `offset`. | +| [order_by](#letsql.vendor.ibis.expr.types.relations.Table.order_by) | Sort a table by one or more expressions. | +| [sample](#letsql.vendor.ibis.expr.types.relations.Table.sample) | Sample a fraction of rows from a table. | +| [select](#letsql.vendor.ibis.expr.types.relations.Table.select) | Compute a new table expression using `exprs` and `named_exprs`. | +| [sql](#letsql.vendor.ibis.expr.types.relations.Table.sql) | Run a SQL query against a table expression. | +| [union](#letsql.vendor.ibis.expr.types.relations.Table.union) | Compute the set union of multiple table expressions. | +| [view](#letsql.vendor.ibis.expr.types.relations.Table.view) | Create a new table expression distinct from the current one. | +| [cache](#letsql.vendor.ibis.expr.types.relations.Table.cache) | Cache the results of a computation to improve performance on subsequent executions. | +| [into_backend](#letsql.vendor.ibis.expr.types.relations.Table.into_backend) | Converts the Expr to a table in the given backend `con` with an optional table name `name`. | + +### alias + +```python +alias(alias) +``` + +Create a table expression with a specific name `alias`. + +This method is useful for exposing an ibis expression to the underlying +backend for use in the +[`Table.sql`](#ibis.expr.types.relations.Table.sql) method. + + + +`.alias` creates a temporary view in the database. + +This side effect will be removed in a future version of xorq and **is +not part of the public API**. + + + +#### Parameters + +| Name | Type | Description | Default | +|-------|------------------|------------------------------|------------| +| alias | [str](%60str%60) | Name of the child expression | *required* | + +#### Returns + +| Name | Type | Description | +|--------|-----------------------------------------------|------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | An table expression | + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch() +>>> expr = t.alias("pingüinos").sql('SELECT * FROM "pingüinos" LIMIT 5') +>>> expr +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ float64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186.0 │ … │ +│ Adelie │ Torgersen │ 40.3 │ 18.0 │ 195.0 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Torgersen │ 36.7 │ 19.3 │ 193.0 │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +``` + +### as_scalar + +```python +as_scalar() +``` + +Inform ibis that the table expression should be treated as a scalar. + +Note that the table must have exactly one column and one row for this to +work. If the table has more than one column an error will be raised in +expression construction time. If the table has more than one row an +error will be raised by the backend when the expression is executed. + +#### Returns + +| Name | Type | Description | +|--------|-----------------------------------------------|-----------------| +| | [Scalar](%60letsql.vendor.ibis.expr.types.uuid.Scalar%60) | A scalar subquery | + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch() +>>> heavy_gentoo = t.filter(t.species == "Gentoo", t.body_mass_g > 6200) +>>> from_that_island = t.filter(t.island == heavy_gentoo.select("island").as_scalar()) +>>> from_that_island.species.value_counts().order_by("species") +┏━━━━━━━━━┳━━━━━━━━━━━━━━━┓ +┃ species ┃ species_count ┃ +┡━━━━━━━━━╇━━━━━━━━━━━━━━━┩ +│ string │ int64 │ +├─────────┼───────────────┤ +│ Adelie │ 44 │ +│ Gentoo │ 124 │ +└─────────┴───────────────┘ +``` + +### count + +```python +count(where=None) +``` + +Compute the number of rows in the table. + +#### Parameters + +| Name | Type | Description | Default | +|----|----------------------------------------|-----------------------|-----| +| where | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| None | Optional boolean expression to filter rows when counting. | `None` | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------------|--------------------| +| | [IntegerScalar](%60letsql.vendor.ibis.expr.types.numeric.IntegerScalar%60) | Number of rows in the table | + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.memtable({"a": ["foo", "bar", "baz"]}) +>>> t +┏━━━━━━━━┓ +┃ a ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ foo │ +│ bar │ +│ baz │ +└────────┘ +>>> t.count() +┌───┐ +│ 3 │ +└───┘ +>>> t.count(t.a != "foo") +┌───┐ +│ 2 │ +└───┘ +>>> type(t.count()) + +``` + +### difference + +```python +difference(table, *rest, distinct=True) +``` + +Compute the set difference of multiple table expressions. + +The input tables must have identical schemas. + +#### Parameters + +| Name | Type | Description | Default | +|------|-----------------------------|------------------------------|-------| +| table | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | A table expression | *required* | +| \*rest | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | Additional table expressions | `()` | +| distinct | [bool](%60bool%60) | Only diff distinct rows not occurring in the calling table | `True` | + +#### See Also + +[`ibis.difference`](./expression-tables.qmd#ibis.difference) + +#### Returns + +| Name | Type | Description | +|------|--------------------------------|----------------------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | The rows present in `self` that are not present in `tables`. | + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t1 = ls.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = ls.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> t1.difference(t2) +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +└───────┘ +``` + +### distinct + +```python +distinct(on=None, keep='first') +``` + +Return a Table with duplicate rows removed. + +Similar to `pandas.DataFrame.drop_duplicates()`. + + +Some backends do not support `keep='last'` + + +#### Parameters + +| Name | Type | Description | Default | +|---|--------------------------------|-----------------------------------|---| +| on | [str](%60str%60) \| [Iterable](%60collections.abc.Iterable%60)\[[str](%60str%60)\] \| [s](%60letsql.vendor.ibis.selectors%60).[Selector](%60letsql.vendor.ibis.selectors.Selector%60) \| None | Only consider certain columns for identifying duplicates. By default, deduplicate all of the columns. | `None` | +| keep | [Literal](%60typing.Literal%60)\['first', 'last'\] \| None | Determines which duplicates to keep. - `"first"`: Drop duplicates except for the first occurrence. - `"last"`: Drop duplicates except for the last occurrence. - `None`: Drop all duplicates | `'first'` | + +#### Examples + +```python +>>> import letsql as ls +>>> import letsql.examples as ex +>>> import letsql.selectors as s +>>> ls.options.interactive = True +>>> t = ex.penguins.fetch() +>>> t +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ float64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186.0 │ … │ +│ Adelie │ Torgersen │ 40.3 │ 18.0 │ 195.0 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Torgersen │ 36.7 │ 19.3 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 39.3 │ 20.6 │ 190.0 │ … │ +│ Adelie │ Torgersen │ 38.9 │ 17.8 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.2 │ 19.6 │ 195.0 │ … │ +│ Adelie │ Torgersen │ 34.1 │ 18.1 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 42.0 │ 20.2 │ 190.0 │ … │ +│ … │ … │ … │ … │ … │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +``` + +Compute the distinct rows of a subset of columns + +```python +>>> t[["species", "island"]].distinct().order_by(s.all()) +┏━━━━━━━━━━━┳━━━━━━━━━━━┓ +┃ species ┃ island ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━┩ +│ string │ string │ +├───────────┼───────────┤ +│ Adelie │ Biscoe │ +│ Adelie │ Dream │ +│ Adelie │ Torgersen │ +│ Chinstrap │ Dream │ +│ Gentoo │ Biscoe │ +└───────────┴───────────┘ +``` + +Drop all duplicate rows except the first + +```python +>>> t.distinct(on=["species", "island"], keep="first").order_by(s.all()) +┏━━━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_… ┃ flipper_length_mm ┃ ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━┩ +│ string │ string │ float64 │ float64 │ float64 │ │ +├───────────┼───────────┼────────────────┼──────────────┼───────────────────┼──┤ +│ Adelie │ Biscoe │ 37.8 │ 18.3 │ 174.0 │ │ +│ Adelie │ Dream │ 39.5 │ 16.7 │ 178.0 │ │ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ │ +│ Chinstrap │ Dream │ 46.5 │ 17.9 │ 192.0 │ │ +│ Gentoo │ Biscoe │ 46.1 │ 13.2 │ 211.0 │ │ +└───────────┴───────────┴────────────────┴──────────────┴───────────────────┴──┘ +``` + +Drop all duplicate rows except the last + +```python +>>> t.distinct(on=["species", "island"], keep="last").order_by(s.all()) +┏━━━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_… ┃ flipper_length_mm ┃ ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━┩ +│ string │ string │ float64 │ float64 │ float64 │ │ +├───────────┼───────────┼────────────────┼──────────────┼───────────────────┼──┤ +│ Adelie │ Biscoe │ 42.7 │ 18.3 │ 196.0 │ │ +│ Adelie │ Dream │ 41.5 │ 18.5 │ 201.0 │ │ +│ Adelie │ Torgersen │ 43.1 │ 19.2 │ 197.0 │ │ +│ Chinstrap │ Dream │ 50.2 │ 18.7 │ 198.0 │ │ +│ Gentoo │ Biscoe │ 49.9 │ 16.1 │ 213.0 │ │ +└───────────┴───────────┴────────────────┴──────────────┴───────────────────┴──┘ +``` + +Drop all duplicated rows + +```python +>>> expr = t.distinct(on=["species", "island", "year", "bill_length_mm"], keep=None) +>>> expr.count() +┌─────┐ +│ 273 │ +└─────┘ +>>> t.count() +┌─────┐ +│ 344 │ +└─────┘ +``` + +You can pass [`selectors`](./selectors.qmd) to `on` + +```python +>>> t.distinct(on=~s.numeric()) +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ int64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Biscoe │ 37.8 │ 18.3 │ 174 │ … │ +│ Adelie │ Biscoe │ 37.7 │ 18.7 │ 180 │ … │ +│ Adelie │ Dream │ 39.5 │ 16.7 │ 178 │ … │ +│ Adelie │ Dream │ 37.2 │ 18.1 │ 178 │ … │ +│ Adelie │ Dream │ 37.5 │ 18.9 │ 179 │ … │ +│ Gentoo │ Biscoe │ 46.1 │ 13.2 │ 211 │ … │ +│ Gentoo │ Biscoe │ 50.0 │ 16.3 │ 230 │ … │ +│ … │ … │ … │ … │ … │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +``` + +The only valid values of `keep` are `"first"`, `"last"` and +[](%60None%60). + +```python +>>> t.distinct(on="species", keep="second") # quartodoc: +EXPECTED_FAILURE +Traceback (most recent call last): + ... +letsql.vendor.ibis.common.exceptions.LetSQLError: Invalid value for `keep`: 'second', must be 'first', 'last' or None +``` + +### dropna + +```python +dropna(subset=None, how='any') +``` + +Deprecated - use `drop_null` instead. + +### fillna + +```python +fillna(replacements) +``` + +Deprecated - use `fill_null` instead. + +### filter + +```python +filter(*predicates) +``` + +Select rows from `table` based on `predicates`. + +#### Parameters + +| Name | Type | Description | Default | +|----|------------------------------------------------------|------------|---| +| predicates | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) \| [Sequence](%60collections.abc.Sequence%60)\[[ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60)\] \| [IfAnyAll](%60letsql.vendor.ibis.selectors.IfAnyAll%60) | Boolean value expressions used to select rows in `table`. | `()` | + +#### Returns + +| Name | Type | Description | +|-------|--------------------------------------------|---------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | Filtered table expression | + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch() +>>> t +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ float64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186.0 │ … │ +│ Adelie │ Torgersen │ 40.3 │ 18.0 │ 195.0 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Torgersen │ 36.7 │ 19.3 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 39.3 │ 20.6 │ 190.0 │ … │ +│ Adelie │ Torgersen │ 38.9 │ 17.8 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.2 │ 19.6 │ 195.0 │ … │ +│ Adelie │ Torgersen │ 34.1 │ 18.1 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 42.0 │ 20.2 │ 190.0 │ … │ +│ … │ … │ … │ … │ … │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +>>> t.filter([t.species == "Adelie", t.body_mass_g > 3500]).sex.value_counts().drop_null( +... "sex" +... ).order_by("sex") +┏━━━━━━━━┳━━━━━━━━━━━┓ +┃ sex ┃ sex_count ┃ +┡━━━━━━━━╇━━━━━━━━━━━┩ +│ string │ int64 │ +├────────┼───────────┤ +│ female │ 22 │ +│ male │ 68 │ +└────────┴───────────┘ +``` + +### intersect + +```python +intersect(table, *rest, distinct=True) +``` + +Compute the set intersection of multiple table expressions. + +The input tables must have identical schemas. + +#### Parameters + +| Name | Type | Description | Default | +|--------|-------------------------------------|--------------------|---------| +| table | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | A table expression | *required* | +| \*rest | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | Additional table expressions | `()` | +| distinct | [bool](%60bool%60) | Only return distinct rows | `True` | + +#### Returns + +| Name | Type | Description | +|------|--------------------------------|----------------------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | A new table containing the intersection of all input tables. | + +#### See Also + +[`ibis.intersect`](./expression-tables.qmd#ibis.intersect) + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t1 = ls.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = ls.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> t1.intersect(t2) +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +└───────┘ +``` + +### limit + +```python +limit(n, offset=0) +``` + +Select `n` rows from `self` starting at `offset`. + + +The result set is not deterministic without a call to +[`order_by`](#ibis.expr.types.relations.Table.order_by).] + + +#### Parameters + +| Name | Type | Description | Default | +|------|-------------|------------------------------------------------|--------| +| n | [int](%60int%60) \| None | Number of rows to include. If `None`, the entire table is selected starting from `offset`. | *required* | +| offset | [int](%60int%60) | Number of rows to skip first | `0` | + +#### Returns + +| Name | Type | Description | +|------|-----------------------------------|-------------------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | The first `n` rows of `self` starting at `offset` | + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.memtable({"a": [1, 1, 2], "b": ["c", "a", "a"]}) +>>> t +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ c │ +│ 1 │ a │ +│ 2 │ a │ +└───────┴────────┘ +>>> t.limit(2) +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ c │ +│ 1 │ a │ +└───────┴────────┘ +``` + +You can use `None` with `offset` to slice starting from a particular row + +```python +>>> t.limit(None, offset=1) +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ a │ +│ 2 │ a │ +└───────┴────────┘ +``` + +#### See Also + +[`Table.order_by`](#ibis.expr.types.relations.Table.order_by) + +### order_by + +```python +order_by(*by) +``` + +Sort a table by one or more expressions. + +Similar to `pandas.DataFrame.sort_values()`. + +#### Parameters + +| Name | Type | Description | Default | +|--|--------------------------------------------------------------|------|---| +| by | [str](%60str%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[Column](%60letsql.vendor.ibis.expr.types.Column%60) \| [s](%60letsql.vendor.ibis.selectors%60).[Selector](%60letsql.vendor.ibis.selectors.Selector%60) \| [Sequence](%60collections.abc.Sequence%60)\[[str](%60str%60)\] \| [Sequence](%60collections.abc.Sequence%60)\[[ir](%60letsql.vendor.ibis.expr.types%60).[Column](%60letsql.vendor.ibis.expr.types.Column%60)\] \| [Sequence](%60collections.abc.Sequence%60)\[[s](%60letsql.vendor.ibis.selectors%60).[Selector](%60letsql.vendor.ibis.selectors.Selector%60)\] \| None | Expressions to sort the table by. | `()` | + +#### Returns + +| Name | Type | Description | +|--------|--------------------------------------------------|--------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | Sorted table | + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.memtable( +... { +... "a": [3, 2, 1, 3], +... "b": ["a", "B", "c", "D"], +... "c": [4, 6, 5, 7], +... } +... ) +>>> t +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 3 │ a │ 4 │ +│ 2 │ B │ 6 │ +│ 1 │ c │ 5 │ +│ 3 │ D │ 7 │ +└───────┴────────┴───────┘ +``` + +Sort by b. Default is ascending. Note how capital letters come before +lowercase + +```python +>>> t.order_by("b") +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 2 │ B │ 6 │ +│ 3 │ D │ 7 │ +│ 3 │ a │ 4 │ +│ 1 │ c │ 5 │ +└───────┴────────┴───────┘ +``` + +Sort in descending order + +```python +>>> t.order_by(ls.desc("b")) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 1 │ c │ 5 │ +│ 3 │ a │ 4 │ +│ 3 │ D │ 7 │ +│ 2 │ B │ 6 │ +└───────┴────────┴───────┘ +``` + +You can also use the deferred API to get the same result + +```python +>>> from letsql import _ +>>> t.order_by(_.b.desc()) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 1 │ c │ 5 │ +│ 3 │ a │ 4 │ +│ 3 │ D │ 7 │ +│ 2 │ B │ 6 │ +└───────┴────────┴───────┘ +``` + +Sort by multiple columns/expressions + +```python +>>> t.order_by(["a", _.c.desc()]) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 1 │ c │ 5 │ +│ 2 │ B │ 6 │ +│ 3 │ D │ 7 │ +│ 3 │ a │ 4 │ +└───────┴────────┴───────┘ +``` + +You can actually pass arbitrary expressions to use as sort keys. For +example, to ignore the case of the strings in column `b` + +```python +>>> t.order_by(_.b.lower()) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 3 │ a │ 4 │ +│ 2 │ B │ 6 │ +│ 1 │ c │ 5 │ +│ 3 │ D │ 7 │ +└───────┴────────┴───────┘ +``` + +This means that shuffling a Table is super simple + +```python +>>> t.order_by(ls.random()) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 1 │ c │ 5 │ +│ 3 │ D │ 7 │ +│ 3 │ a │ 4 │ +│ 2 │ B │ 6 │ +└───────┴────────┴───────┘ +``` + +[Selectors](./selectors.qmd) are allowed as sort keys and are a concise +way to sort by multiple columns matching some criteria + +```python +>>> import letsql.selectors as s +>>> penguins = ls.examples.penguins.fetch() +>>> penguins[["year", "island"]].value_counts().order_by(s.startswith("year")) +┏━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓ +┃ year ┃ island ┃ year_island_count ┃ +┡━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼───────────┼───────────────────┤ +│ 2007 │ Torgersen │ 20 │ +│ 2007 │ Biscoe │ 44 │ +│ 2007 │ Dream │ 46 │ +│ 2008 │ Torgersen │ 16 │ +│ 2008 │ Dream │ 34 │ +│ 2008 │ Biscoe │ 64 │ +│ 2009 │ Torgersen │ 16 │ +│ 2009 │ Dream │ 44 │ +│ 2009 │ Biscoe │ 60 │ +└───────┴───────────┴───────────────────┘ +``` + +Use the [`across`](./selectors.qmd#ibis.selectors.across) selector to +apply a specific order to multiple columns + +```python +>>> penguins[["year", "island"]].value_counts().order_by( +... s.across(s.startswith("year"), _.desc()) +... ) +┏━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓ +┃ year ┃ island ┃ year_island_count ┃ +┡━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼───────────┼───────────────────┤ +│ 2009 │ Biscoe │ 60 │ +│ 2009 │ Dream │ 44 │ +│ 2009 │ Torgersen │ 16 │ +│ 2008 │ Biscoe │ 64 │ +│ 2008 │ Dream │ 34 │ +│ 2008 │ Torgersen │ 16 │ +│ 2007 │ Dream │ 46 │ +│ 2007 │ Biscoe │ 44 │ +│ 2007 │ Torgersen │ 20 │ +└───────┴───────────┴───────────────────┘ +``` + +### sample + +```python +sample(fraction, *, method='row', seed=None) +``` + +Sample a fraction of rows from a table. + + + +Sampling is by definition a random operation. Some backends support +specifying a `seed` for repeatable results, but not all backends support +that option. And some backends (duckdb, for example) do support +specifying a seed but may still not have repeatable results in all +cases. + +In all cases, results are backend-specific. An execution against one +backend is unlikely to sample the same rows when executed against a +different backend, even with the same `seed` set. + + + +#### Parameters + +| Name | Type | Description | Default | +|---|--------|-----------------------------------------------------------|---| +| fraction | [float](%60float%60) | The percentage of rows to include in the sample, expressed as a float between 0 and 1. | *required* | +| method | [Literal](%60typing.Literal%60)\['row', 'block'\] | The sampling method to use. The default is “row”, which includes each row with a probability of `fraction`. If method is “block”, some backends may instead perform sampling a fraction of blocks of rows (where “block” is a backend dependent definition). This is identical to “row” for backends lacking a blockwise sampling implementation. For those coming from SQL, “row” and “block” correspond to “bernoulli” and “system” respectively in a TABLESAMPLE clause. | `'row'` | +| seed | [int](%60int%60) \| None | An optional random seed to use, for repeatable sampling. The range of possible seed values is backend specific (most support at least `[0, 2**31 - 1]`). Backends that never support specifying a seed for repeatable sampling will error appropriately. Note that some backends (like DuckDB) do support specifying a seed, but may still not have repeatable results in all cases. | `None` | + +#### Returns + +| Name | Type | Description | +|------|-----------------------------------|-------------------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | The input table, with `fraction` of rows selected. | + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.memtable({"x": [1, 2, 3, 4], "y": ["a", "b", "c", "d"]}) +>>> t +┏━━━━━━━┳━━━━━━━━┓ +┃ x ┃ y ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ a │ +│ 2 │ b │ +│ 3 │ c │ +│ 4 │ d │ +└───────┴────────┘ +``` + +Sample approximately half the rows, with a seed specified for +reproducibility. + +```python +>>> t.sample(0.5, seed=1234) +┏━━━━━━━┳━━━━━━━━┓ +┃ x ┃ y ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 2 │ b │ +│ 3 │ c │ +└───────┴────────┘ +``` + +### select + +```python +select(*exprs, **named_exprs) +``` + +Compute a new table expression using `exprs` and `named_exprs`. + +Passing an aggregate function to this method will broadcast the +aggregate’s value over the number of rows in the table and automatically +constructs a window function expression. See the examples section for +more details. + +For backwards compatibility the keyword argument `exprs` is reserved and +cannot be used to name an expression. This behavior will be removed in +v4. + +#### Parameters + +| Name | Type | Description | Default | +|----|--------------------------------------------------|---------------|----| +| exprs | [ir](%60letsql.vendor.ibis.expr.types%60).[Value](%60letsql.vendor.ibis.expr.types.Value%60) \| [str](%60str%60) \| [Iterable](%60collections.abc.Iterable%60)\[[ir](%60letsql.vendor.ibis.expr.types%60).[Value](%60letsql.vendor.ibis.expr.types.Value%60) \| [str](%60str%60)\] | Column expression, string, or list of column expressions and strings. | `()` | +| named_exprs | [ir](%60letsql.vendor.ibis.expr.types%60).[Value](%60letsql.vendor.ibis.expr.types.Value%60) \| [str](%60str%60) | Column expressions | `{}` | + +#### Returns + +| Name | Type | Description | +|--------|------------------------------------------------|----------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | Table expression | + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch() +>>> t +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ float64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186.0 │ … │ +│ Adelie │ Torgersen │ 40.3 │ 18.0 │ 195.0 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Torgersen │ 36.7 │ 19.3 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 39.3 │ 20.6 │ 190.0 │ … │ +│ Adelie │ Torgersen │ 38.9 │ 17.8 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.2 │ 19.6 │ 195.0 │ … │ +│ Adelie │ Torgersen │ 34.1 │ 18.1 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 42.0 │ 20.2 │ 190.0 │ … │ +│ … │ … │ … │ … │ … │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +``` + +Simple projection + +```python +>>> t.select("island", "bill_length_mm").head() +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┓ +┃ island ┃ bill_length_mm ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼────────────────┤ +│ Torgersen │ 39.1 │ +│ Torgersen │ 39.5 │ +│ Torgersen │ 40.3 │ +│ Torgersen │ NULL │ +│ Torgersen │ 36.7 │ +└───────────┴────────────────┘ +``` + +In that simple case, you could also just use python’s indexing syntax + +```python +>>> t[["island", "bill_length_mm"]].head() +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┓ +┃ island ┃ bill_length_mm ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼────────────────┤ +│ Torgersen │ 39.1 │ +│ Torgersen │ 39.5 │ +│ Torgersen │ 40.3 │ +│ Torgersen │ NULL │ +│ Torgersen │ 36.7 │ +└───────────┴────────────────┘ +``` + +Projection by zero-indexed column position + +```python +>>> t.select(t[0], t[4]).head() +┏━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓ +┃ species ┃ flipper_length_mm ┃ +┡━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├─────────┼───────────────────┤ +│ Adelie │ 181.0 │ +│ Adelie │ 186.0 │ +│ Adelie │ 195.0 │ +│ Adelie │ NULL │ +│ Adelie │ 193.0 │ +└─────────┴───────────────────┘ +``` + +Projection with renaming and compute in one call + +```python +>>> t.select(next_year=t.year + 1).head() +┏━━━━━━━━━━━┓ +┃ next_year ┃ +┡━━━━━━━━━━━┩ +│ int64 │ +├───────────┤ +│ 2008 │ +│ 2008 │ +│ 2008 │ +│ 2008 │ +│ 2008 │ +└───────────┘ +``` + +You can do the same thing with a named expression, and using the +deferred API + +```python +>>> from letsql import _ +>>> t.select((_.year + 1).name("next_year")).head() +┏━━━━━━━━━━━┓ +┃ next_year ┃ +┡━━━━━━━━━━━┩ +│ int64 │ +├───────────┤ +│ 2008 │ +│ 2008 │ +│ 2008 │ +│ 2008 │ +│ 2008 │ +└───────────┘ +``` + +Projection with aggregation expressions + +```python +>>> t.select("island", bill_mean=t.bill_length_mm.mean()).head() +┏━━━━━━━━━━━┳━━━━━━━━━━━┓ +┃ island ┃ bill_mean ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼───────────┤ +│ Torgersen │ 43.92193 │ +│ Torgersen │ 43.92193 │ +│ Torgersen │ 43.92193 │ +│ Torgersen │ 43.92193 │ +│ Torgersen │ 43.92193 │ +└───────────┴───────────┘ +``` + +Projection with a selector + +```python +>>> import letsql.selectors as s +>>> t.select(s.numeric() & ~s.cols("year")).head() +┏━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┓ +┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ body_mass_g ┃ +┡━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━┩ +│ float64 │ float64 │ float64 │ float64 │ +├────────────────┼───────────────┼───────────────────┼─────────────┤ +│ 39.1 │ 18.7 │ 181.0 │ 3750.0 │ +│ 39.5 │ 17.4 │ 186.0 │ 3800.0 │ +│ 40.3 │ 18.0 │ 195.0 │ 3250.0 │ +│ NULL │ NULL │ NULL │ NULL │ +│ 36.7 │ 19.3 │ 193.0 │ 3450.0 │ +└────────────────┴───────────────┴───────────────────┴─────────────┘ +``` + +Projection + aggregation across multiple columns + +```python +>>> from letsql import _ +>>> t.select(s.across(s.numeric() & ~s.cols("year"), _.mean())).head() +┏━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┓ +┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ body_mass_g ┃ +┡━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━┩ +│ float64 │ float64 │ float64 │ float64 │ +├────────────────┼───────────────┼───────────────────┼─────────────┤ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +└────────────────┴───────────────┴───────────────────┴─────────────┘ +``` + +### sql + +```python +sql(query, dialect=None) +``` + +Run a SQL query against a table expression. + +#### Parameters + +| Name | Type | Description | Default | +|------|------------|-----------------------------------------------|-------| +| query | [str](%60str%60) | Query string | *required* | +| dialect | [str](%60str%60) \| None | Optional string indicating the dialect of `query`. Defaults to the backend’s native dialect. | `None` | + +#### Returns + +| Name | Type | Description | +|-------|-------------------------------------------|----------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | An opaque table expression | + +#### Examples + +```python +>>> import letsql as ls +>>> from letsql import _ +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch(table_name="penguins") +>>> expr = t.sql( +... """ +... SELECT island, mean(bill_length_mm) AS avg_bill_length +... FROM penguins +... GROUP BY 1 +... ORDER BY 2 DESC +... """ +... ) +>>> expr +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━┓ +┃ island ┃ avg_bill_length ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼─────────────────┤ +│ Biscoe │ 45.257485 │ +│ Dream │ 44.167742 │ +│ Torgersen │ 38.950980 │ +└───────────┴─────────────────┘ +``` + +Mix and match ibis expressions with SQL queries + +```python +>>> t = ls.examples.penguins.fetch(table_name="penguins") +>>> expr = t.sql( +... """ +... SELECT island, mean(bill_length_mm) AS avg_bill_length +... FROM penguins +... GROUP BY 1 +... ORDER BY 2 DESC +... """ +... ) +>>> expr = expr.mutate( +... island=_.island.lower(), +... avg_bill_length=_.avg_bill_length.round(1), +... ) +>>> expr +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━┓ +┃ island ┃ avg_bill_length ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼─────────────────┤ +│ biscoe │ 45.3 │ +│ torgersen │ 39.0 │ +│ dream │ 44.2 │ +└───────────┴─────────────────┘ +``` + +Because ibis expressions aren’t named, they aren’t visible to subsequent +`.sql` calls. Use the [`alias`](#ibis.expr.types.relations.Table.alias) +method to assign a name to an expression. + +```python +>>> expr.alias("b").sql("SELECT * FROM b WHERE avg_bill_length > 40") +┏━━━━━━━━┳━━━━━━━━━━━━━━━━━┓ +┃ island ┃ avg_bill_length ┃ +┡━━━━━━━━╇━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├────────┼─────────────────┤ +│ biscoe │ 45.3 │ +│ dream │ 44.2 │ +└────────┴─────────────────┘ +``` + +#### See Also + +[`Table.alias`](#ibis.expr.types.relations.Table.alias) + +### union + +```python +union(table, *rest, distinct=False) +``` + +Compute the set union of multiple table expressions. + +The input tables must have identical schemas. + +#### Parameters + +| Name | Type | Description | Default | +|--------|-------------------------------------|--------------------|---------| +| table | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | A table expression | *required* | +| \*rest | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | Additional table expressions | `()` | +| distinct | [bool](%60bool%60) | Only return distinct rows | `False` | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------|--------------------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | A new table containing the union of all input tables. | + +#### See Also + +[`ibis.union`](./expression-tables.qmd#ibis.union) + +#### Examples + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t1 = ls.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = ls.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> t1.union(t2) # union all by default doctest: +SKIP +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +│ 1 │ +│ 2 │ +└───────┘ +>>> t1.union(t2, distinct=True).order_by("a") +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +│ 3 │ +└───────┘ +``` + +### view + +```python +view() +``` + +Create a new table expression distinct from the current one. + +Use this API for any self-referencing operations like a self-join. + +#### Returns + +| Name | Type | Description | +|--------|------------------------------------------------|----------------| +| | [Table](%60letsql.vendor.ibis.expr.types.relations.Table%60) | Table expression | + +### cache + +```python +cache(storage=None) +``` + +Cache the results of a computation to improve performance on subsequent +executions. This method allows you to cache the results of a computation +either in memory, on disk using Parquet files, or in a database table. +The caching strategy and storage location are determined by the storage +parameter. + +#### Parameters + +| Name | Type | Description | Default | +|---|-------|------------------------------------------------------------|---| +| storage | [CacheStorage](%60CacheStorage%60) | The storage strategy to use for caching. Can be one of: - ParquetCacheStorage: Caches results as Parquet files on disk - SourceStorage: Caches results in the source database - ParquetSnapshot: Creates a snapshot of data in Parquet format - SnapshotStorage: Creates a snapshot in the source database If None, uses the default storage configuration. | `None` | + +#### Returns + +| Name | Type | Description | +|------|-------------------------------|-----------------------------------| +| | [Expr](%60letsql.vendor.ibis.expr.types.core.Expr%60) | A new expression that represents the cached computation. | + +#### Notes + +The cache method supports two main strategies: 1. +ModificationTimeStrategy: Tracks changes based on modification time 2. +SnapshotStrategy: Creates point-in-time snapshots of the data + +Each strategy can be combined with either Parquet or database storage. + +#### Examples + +Using ParquetCacheStorage: + +```python +>>> import letsql as ls +>>> from letsql.common.caching import ParquetCacheStorage +>>> from pathlib import Path +>>> pg = ls.postgres.connect_examples() +>>> con = ls.connect() +>>> storage = ParquetCacheStorage(source=con, path=Path.cwd()) +>>> alltypes = pg.table("functional_alltypes") +>>> cached = (alltypes +... .select(alltypes.smallint_col, alltypes.int_col, alltypes.float_col) +... .cache(storage=storage)) +``` + +Using SourceStorage with PostgreSQL: + +```python +>>> from letsql.common.caching import SourceStorage +>>> from letsql import _ +>>> ddb = ls.duckdb.connect() +>>> path = ls.config.options.pins.get_path("batting") +>>> right = (ddb.read_parquet(path, table_name="batting") +... .filter(_.yearID == 2014) +... .pipe(con.register, table_name="ddb-batting")) +>>> left = (pg.table("batting") +... .filter(_.yearID == 2015) +... .pipe(con.register, table_name="pg-batting")) +>>> # Cache the joined result +>>> expr = left.join(right, "playerID").cache(SourceStorage(source=pg)) +``` + +Using cache with filtering: + +```python +>>> cached = alltypes.cache(storage=storage) +>>> expr = cached.filter([ +... cached.float_col > 0, +... cached.smallint_col > 4, +... cached.int_col < cached.float_col * 2 +... ]) +``` + +#### See Also + +ParquetCacheStorage : Storage implementation for Parquet files +SourceStorage : Storage implementation for database tables +ModificationTimeStrategy : Strategy for tracking changes by modification +time SnapshotStrategy : Strategy for creating data snapshots + +#### Notes + +- The cache is identified by a unique key based on the computation and + strategy +- Cache invalidation is handled automatically based on the chosen + strategy +- Cross-source caching (e.g., from PostgreSQL to DuckDB) is supported +- Cache locations can be configured globally through + letsql.config.options + +### into_backend + +```python +into_backend(con, name=None) +``` + +Converts the Expr to a table in the given backend `con` with an optional +table name `name`. + +The table is backed by a PyArrow RecordBatchReader, the +RecordBatchReader is teed so it can safely be reaused without spilling +to disk. + +#### Parameters + +| Name | Type | Description | Default | +|------|------|-----------------------------------------------|------------| +| con | | The backend where the table should be created | *required* | +| name | | The name of the table | `None` | + +#### Examples + +```python +>>> import letsql as ls +>>> from letsql import _ +>>> ls.options.interactive = True +>>> ls_con = ls.connect() +>>> pg_con = ls.postgres.connect_examples() +>>> t = pg_con.table("batting").into_backend(ls_con, "ls_batting") +>>> expr = ( +... t.join(t, "playerID") +... .order_by("playerID", "yearID") +... .limit(15) +... .select(player_id="playerID", year_id="yearID_right") +... ) +>>> expr +┏━━━━━━━━━━━┳━━━━━━━━━┓ +┃ player_id ┃ year_id ┃ +┡━━━━━━━━━━━╇━━━━━━━━━┩ +│ string │ int64 │ +├───────────┼─────────┤ +│ aardsda01 │ 2015 │ +│ aardsda01 │ 2007 │ +│ aardsda01 │ 2006 │ +│ aardsda01 │ 2009 │ +│ aardsda01 │ 2008 │ +│ aardsda01 │ 2010 │ +│ aardsda01 │ 2004 │ +│ aardsda01 │ 2013 │ +│ aardsda01 │ 2012 │ +│ aardsda01 │ 2006 │ +│ … │ … │ +└───────────┴─────────┘ +``` diff --git a/docs/api-reference/expression-strings.mdx b/docs/api-reference/expression-strings.mdx new file mode 100644 index 00000000..f151063e --- /dev/null +++ b/docs/api-reference/expression-strings.mdx @@ -0,0 +1,1395 @@ +--- +title: 'String expressions' +--- + +All string operations are valid for both scalars and columns. + +# StringValue + +```python +StringValue(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [ascii_str](#letsql.vendor.ibis.expr.types.strings.StringValue.ascii_str) | Return the numeric ASCII code of the first character of a string. | +| [authority](#letsql.vendor.ibis.expr.types.strings.StringValue.authority) | Parse a URL and extract authority. | +| [capitalize](#letsql.vendor.ibis.expr.types.strings.StringValue.capitalize) | Uppercase the first letter, lowercase the rest. | +| [concat](#letsql.vendor.ibis.expr.types.strings.StringValue.concat) | Concatenate strings. | +| [contains](#letsql.vendor.ibis.expr.types.strings.StringValue.contains) | Return whether the expression contains `substr`. | +| [endswith](#letsql.vendor.ibis.expr.types.strings.StringValue.endswith) | Determine if `self` ends with `end`. | +| [find](#letsql.vendor.ibis.expr.types.strings.StringValue.find) | Return the position of the first occurrence of substring. | +| [find_in_set](#letsql.vendor.ibis.expr.types.strings.StringValue.find_in_set) | Find the first occurrence of `str_list` within a list of strings. | +| [fragment](#letsql.vendor.ibis.expr.types.strings.StringValue.fragment) | Parse a URL and extract fragment identifier. | +| [host](#letsql.vendor.ibis.expr.types.strings.StringValue.host) | Parse a URL and extract host. | +| [length](#letsql.vendor.ibis.expr.types.strings.StringValue.length) | Compute the length of a string. | +| [levenshtein](#letsql.vendor.ibis.expr.types.strings.StringValue.levenshtein) | Return the Levenshtein distance between two strings. | +| [lower](#letsql.vendor.ibis.expr.types.strings.StringValue.lower) | Convert string to all lowercase. | +| [lpad](#letsql.vendor.ibis.expr.types.strings.StringValue.lpad) | Pad `arg` by truncating on the right or padding on the left. | +| [lstrip](#letsql.vendor.ibis.expr.types.strings.StringValue.lstrip) | Remove whitespace from the left side of string. | +| [path](#letsql.vendor.ibis.expr.types.strings.StringValue.path) | Parse a URL and extract path. | +| [protocol](#letsql.vendor.ibis.expr.types.strings.StringValue.protocol) | Parse a URL and extract protocol. | +| [query](#letsql.vendor.ibis.expr.types.strings.StringValue.query) | Parse a URL and returns query string or query string parameter. | +| [re_extract](#letsql.vendor.ibis.expr.types.strings.StringValue.re_extract) | Return the specified match at `index` from a regex `pattern`. | +| [re_replace](#letsql.vendor.ibis.expr.types.strings.StringValue.re_replace) | Replace all matches found by regex `pattern` with `replacement`. | +| [re_search](#letsql.vendor.ibis.expr.types.strings.StringValue.re_search) | Return whether the values match `pattern`. | +| [re_split](#letsql.vendor.ibis.expr.types.strings.StringValue.re_split) | Split a string by a regular expression `pattern`. | +| [repeat](#letsql.vendor.ibis.expr.types.strings.StringValue.repeat) | Repeat a string `n` times. | +| [replace](#letsql.vendor.ibis.expr.types.strings.StringValue.replace) | Replace each exact match of `pattern` with `replacement`. | +| [reverse](#letsql.vendor.ibis.expr.types.strings.StringValue.reverse) | Reverse the characters of a string. | +| [right](#letsql.vendor.ibis.expr.types.strings.StringValue.right) | Return up to `nchars` from the end of each string. | +| [rpad](#letsql.vendor.ibis.expr.types.strings.StringValue.rpad) | Pad `self` by truncating or padding on the right. | +| [rstrip](#letsql.vendor.ibis.expr.types.strings.StringValue.rstrip) | Remove whitespace from the right side of string. | +| [split](#letsql.vendor.ibis.expr.types.strings.StringValue.split) | Split as string on `delimiter`. | +| [startswith](#letsql.vendor.ibis.expr.types.strings.StringValue.startswith) | Determine whether `self` starts with `start`. | +| [strip](#letsql.vendor.ibis.expr.types.strings.StringValue.strip) | Remove whitespace from left and right sides of a string. | +| [substr](#letsql.vendor.ibis.expr.types.strings.StringValue.substr) | Extract a substring. | +| [to_date](#letsql.vendor.ibis.expr.types.strings.StringValue.to_date) | | +| [translate](#letsql.vendor.ibis.expr.types.strings.StringValue.translate) | Replace `from_str` characters in `self` characters in `to_str`. | +| [upper](#letsql.vendor.ibis.expr.types.strings.StringValue.upper) | Convert string to all uppercase. | +| [userinfo](#letsql.vendor.ibis.expr.types.strings.StringValue.userinfo) | Parse a URL and extract user info. | + +### ascii_str + +```python +ascii_str() +``` + +Return the numeric ASCII code of the first character of a string. + +#### Returns + +| Name | Type | Description | +|------|---------------------------------------|---------------------------| +| | [IntegerValue](%60letsql.vendor.ibis.expr.types.numeric.IntegerValue%60) | ASCII code of the first character of the input | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "def", "ghi"]}) +>>> t.s.ascii_str() +┏━━━━━━━━━━━━━━━━┓ +┃ StringAscii(s) ┃ +┡━━━━━━━━━━━━━━━━┩ +│ int32 │ +├────────────────┤ +│ 97 │ +│ 100 │ +│ 103 │ +└────────────────┘ +``` + +### authority + +```python +authority() +``` + +Parse a URL and extract authority. + +#### Examples + +```python +>>> import ibis +>>> url = ibis.literal("https://user:pass@example.com:80/docs/books") +>>> result = url.authority() # user:pass@example.com:80 +``` + +#### Returns + +| Name | Type | Description | +|-------|------------------------------------------------|------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Extracted string value | + +### capitalize + +```python +capitalize() +``` + +Uppercase the first letter, lowercase the rest. + +This API matches the semantics of the Python [](%60str.capitalize%60) +method. + +#### Returns + +| Name | Type | Description | +|-------|--------------------------------------------------|----------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Capitalized string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["aBC", " abc", "ab cd", None]}) +>>> t.s.capitalize() +┏━━━━━━━━━━━━━━━┓ +┃ Capitalize(s) ┃ +┡━━━━━━━━━━━━━━━┩ +│ string │ +├───────────────┤ +│ Abc │ +│ abc │ +│ Ab cd │ +│ NULL │ +└───────────────┘ +``` + +### concat + +```python +concat(other, *args) +``` + +Concatenate strings. + +NULLs are propagated. This methods is equivalent to using the `+` +operator. + +#### Parameters + +| Name | Type | Description | Default | +|-----|------------------------------------------|------------------|-------| +| other | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | String to concatenate | *required* | +| args | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Additional strings to concatenate | `()` | + +#### Returns + +| Name | Type | Description | +|-------|-----------------------------------------------|-------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | All strings concatenated | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", None]}) +>>> t.s.concat("xyz", "123") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringConcat((s, 'xyz', '123')) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────────────────────┤ +│ abcxyz123 │ +│ NULL │ +└─────────────────────────────────┘ +>>> t.s + "xyz" +┏━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringConcat((s, 'xyz')) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├──────────────────────────┤ +│ abcxyz │ +│ NULL │ +└──────────────────────────┘ +``` + +### contains + +```python +contains(substr) +``` + +Return whether the expression contains `substr`. + +#### Parameters + +| Name | Type | Description | Default | +|------|--------------------------------------------|-----------------|--------| +| substr | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Substring for which to check | *required* | + +#### Returns + +| Name | Type | Description | +|-----|-----------------------------------|--------------------------------| +| | [BooleanValue](%60letsql.vendor.ibis.expr.types.logical.BooleanValue%60) | Boolean indicating the presence of `substr` in the expression | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["bab", "ddd", "eaf"]}) +>>> t.s.contains("a") +┏━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringContains(s, 'a') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├────────────────────────┤ +│ True │ +│ False │ +│ True │ +└────────────────────────┘ +``` + +### endswith + +```python +endswith(end) +``` + +Determine if `self` ends with `end`. + +#### Parameters + +| Name | Type | Description | Default | +|------|-----------------------------------------------|-------------|--------| +| end | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Suffix to check for | *required* | + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------|----------------------------| +| | [BooleanValue](%60letsql.vendor.ibis.expr.types.logical.BooleanValue%60) | Boolean indicating whether `self` ends with `end` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["Ibis project", "GitHub"]}) +>>> t.s.endswith("project") +┏━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ EndsWith(s, 'project') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├────────────────────────┤ +│ True │ +│ False │ +└────────────────────────┘ +``` + +### find + +```python +find(substr, start=None, end=None) +``` + +Return the position of the first occurrence of substring. + +#### Parameters + +| Name | Type | Description | Default | +|----|----------------------------------------|------------------------|-----| +| substr | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Substring to search for | *required* | +| start | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) \| None | Zero based index of where to start the search | `None` | +| end | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) \| None | Zero based index of where to stop the search. Currently not implemented. | `None` | + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------|-----------------------------| +| | [IntegerValue](%60letsql.vendor.ibis.expr.types.numeric.IntegerValue%60) | Position of `substr` in `arg` starting from `start` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "bac", "bca"]}) +>>> t.s.find("a") +┏━━━━━━━━━━━━━━━━━━━━┓ +┃ StringFind(s, 'a') ┃ +┡━━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ +├────────────────────┤ +│ 0 │ +│ 1 │ +│ 2 │ +└────────────────────┘ +>>> t.s.find("z") +┏━━━━━━━━━━━━━━━━━━━━┓ +┃ StringFind(s, 'z') ┃ +┡━━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ +├────────────────────┤ +│ -1 │ +│ -1 │ +│ -1 │ +└────────────────────┘ +``` + +### find_in_set + +```python +find_in_set(str_list) +``` + +Find the first occurrence of `str_list` within a list of strings. + +No string in `str_list` can have a comma. + +#### Parameters + +| Name | Type | Description | Default | +|--------|---------------------------------------|----------------|----------| +| str_list | [Sequence](%60collections.abc.Sequence%60)\[[str](%60str%60)\] | Sequence of strings | *required* | + +#### Returns + +| Name | Type | Description | +|-----|-----------------------------|---------------------------------------| +| | [IntegerValue](%60letsql.vendor.ibis.expr.types.numeric.IntegerValue%60) | Position of `str_list` in `self`. Returns -1 if `self` isn’t found or if `self` contains `','`. | + +#### Examples + +```python +>>> import ibis +>>> table = ibis.table(dict(string_col="string")) +>>> result = table.string_col.find_in_set(["a", "b"]) +``` + +### fragment + +```python +fragment() +``` + +Parse a URL and extract fragment identifier. + +#### Examples + +```python +>>> import ibis +>>> url = ibis.literal("https://example.com:80/docs/#DOWNLOADING") +>>> result = url.fragment() # DOWNLOADING +``` + +#### Returns + +| Name | Type | Description | +|-------|------------------------------------------------|------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Extracted string value | + +### host + +```python +host() +``` + +Parse a URL and extract host. + +#### Examples + +```python +>>> import ibis +>>> url = ibis.literal("https://user:pass@example.com:80/docs/books") +>>> result = url.host() # example.com +``` + +#### Returns + +| Name | Type | Description | +|-------|------------------------------------------------|------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Extracted string value | + +### length + +```python +length() +``` + +Compute the length of a string. + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------|--------------------------| +| | [IntegerValue](%60letsql.vendor.ibis.expr.types.numeric.IntegerValue%60) | The length of each string in the expression | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["aaa", "a", "aa"]}) +>>> t.s.length() +┏━━━━━━━━━━━━━━━━━┓ +┃ StringLength(s) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ int32 │ +├─────────────────┤ +│ 3 │ +│ 1 │ +│ 2 │ +└─────────────────┘ +``` + +### levenshtein + +```python +levenshtein(other) +``` + +Return the Levenshtein distance between two strings. + +#### Parameters + +| Name | Type | Description | Default | +|------|-------------------------------------------|---------------|---------| +| other | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | String to compare to | *required* | + +#### Returns + +| Name | Type | Description | +|------|-----------------------------------------|--------------------------| +| | [IntegerValue](%60letsql.vendor.ibis.expr.types.numeric.IntegerValue%60) | The edit distance between the two strings | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> s = ibis.literal("kitten") +>>> s.levenshtein("sitting") +┌───┐ +│ 3 │ +└───┘ +``` + +### lower + +```python +lower() +``` + +Convert string to all lowercase. + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|---------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Lowercase string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["AAA", "a", "AA"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ AAA │ +│ a │ +│ AA │ +└────────┘ +>>> t.s.lower() +┏━━━━━━━━━━━━━━┓ +┃ Lowercase(s) ┃ +┡━━━━━━━━━━━━━━┩ +│ string │ +├──────────────┤ +│ aaa │ +│ a │ +│ aa │ +└──────────────┘ +``` + +### lpad + +```python +lpad(length, pad=' ') +``` + +Pad `arg` by truncating on the right or padding on the left. + +#### Parameters + +| Name | Type | Description | Default | +|-----|--------------------------------------------------|------------|------| +| length | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) | Length of output string | *required* | +| pad | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Pad character | `' '` | + +#### Returns + +| Name | Type | Description | +|-------|--------------------------------------------------|----------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Left-padded string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "def", "ghij"]}) +>>> t.s.lpad(5, "-") +┏━━━━━━━━━━━━━━━━━┓ +┃ LPad(s, 5, '-') ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────┤ +│ --abc │ +│ --def │ +│ -ghij │ +└─────────────────┘ +``` + +### lstrip + +```python +lstrip() +``` + +Remove whitespace from the left side of string. + +#### Returns + +| Name | Type | Description | +|-------|-------------------------------------------------|-----------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Left-stripped string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["\ta\t", "\nb\n", "\vc\t"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ \ta\t │ +│ \nb\n │ +│ \vc\t │ +└────────┘ +>>> t.s.lstrip() +┏━━━━━━━━━━━┓ +┃ LStrip(s) ┃ +┡━━━━━━━━━━━┩ +│ string │ +├───────────┤ +│ a\t │ +│ b\n │ +│ c\t │ +└───────────┘ +``` + +### path + +```python +path() +``` + +Parse a URL and extract path. + +#### Examples + +```python +>>> import ibis +>>> url = ibis.literal( +... "https://example.com:80/docs/books/tutorial/index.html?name=networking" +... ) +>>> result = url.path() # docs/books/tutorial/index.html +``` + +#### Returns + +| Name | Type | Description | +|-------|------------------------------------------------|------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Extracted string value | + +### protocol + +```python +protocol() +``` + +Parse a URL and extract protocol. + +#### Examples + +```python +>>> import ibis +>>> url = ibis.literal("https://user:pass@example.com:80/docs/books") +>>> result = url.protocol() # https +``` + +#### Returns + +| Name | Type | Description | +|-------|------------------------------------------------|------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Extracted string value | + +### query + +```python +query(key=None) +``` + +Parse a URL and returns query string or query string parameter. + +If key is passed, return the value of the query string parameter named. +If key is absent, return the query string. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------------------------------------|---------------|-------| +| key | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) \| None | Query component to extract | `None` | + +#### Examples + +```python +>>> import ibis +>>> url = ibis.literal( +... "https://example.com:80/docs/books/tutorial/index.html?name=networking" +... ) +>>> result = url.query() # name=networking +>>> query_name = url.query("name") # networking +``` + +#### Returns + +| Name | Type | Description | +|-------|------------------------------------------------|------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Extracted string value | + +### re_extract + +```python +re_extract(pattern, index) +``` + +Return the specified match at `index` from a regex `pattern`. + +#### Parameters + +| Name | Type | Description | Default | +|---|-------------------|------------------------------------------------|---| +| pattern | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Regular expression pattern string | *required* | +| index | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) | The index of the match group to return. The behavior of this function follows the behavior of Python’s [`match objects`](https://docs.python.org/3/library/re.html#match-objects): when `index` is zero and there’s a match, return the entire match, otherwise return the content of the `index`-th match group. | *required* | + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------|-----------------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Extracted match or whole string if `index` is zero | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "bac", "bca"]}) +``` + +Extract a specific group + +```python +>>> t.s.re_extract(r"^(a)bc", 1) +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexExtract(s, '^(a)bc', 1) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├──────────────────────────────┤ +│ a │ +│ ~ │ +│ ~ │ +└──────────────────────────────┘ +``` + +Extract the entire match + +```python +>>> t.s.re_extract(r"^(a)bc", 0) +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexExtract(s, '^(a)bc', 0) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├──────────────────────────────┤ +│ abc │ +│ ~ │ +│ ~ │ +└──────────────────────────────┘ +``` + +### re_replace + +```python +re_replace(pattern, replacement) +``` + +Replace all matches found by regex `pattern` with `replacement`. + +#### Parameters + +| Name | Type | Description | Default | +|-------|---------------------------------------|--------------------|-------| +| pattern | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Regular expression string | *required* | +| replacement | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Replacement string or regular expression | *required* | + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|--------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Modified string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "bac", "bca", "this has multi \t whitespace"]}) +>>> s = t.s +``` + +Replace all “a”s that are at the beginning of the string with “b”: + +```python +>>> s.re_replace("^a", "b") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexReplace(s, '^a', 'b') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├───────────────────────────────┤ +│ bbc │ +│ bac │ +│ bca │ +│ this has multi \t whitespace │ +└───────────────────────────────┘ +``` + +Double up any “a”s or “b”s, using capture groups and backreferences: + +```python +>>> s.re_replace("([ab])", r"\0\0") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexReplace(s, '()', '\\0\\0') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────────────────────────┤ +│ aabbc │ +│ bbaac │ +│ bbcaa │ +│ this haas multi \t whitespaace │ +└─────────────────────────────────────┘ +``` + +Normalize all whitespace to a single space: + +```python +>>> s.re_replace(r"\s+", " ") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexReplace(s, '\\s+', ' ') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├──────────────────────────────┤ +│ abc │ +│ bac │ +│ bca │ +│ this has multi whitespace │ +└──────────────────────────────┘ +``` + +### re_search + +```python +re_search(pattern) +``` + +Return whether the values match `pattern`. + +Returns `True` if the regex matches a string and `False` otherwise. + +#### Parameters + +| Name | Type | Description | Default | +|------|-----------------------------------------|-------------------|-------| +| pattern | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Regular expression use for searching | *required* | + +#### Returns + +| Name | Type | Description | +|-------|-------------------------------------------------|----------------| +| | [BooleanValue](%60letsql.vendor.ibis.expr.types.logical.BooleanValue%60) | Indicator of matches | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["Ibis project", "GitHub"]}) +>>> t.s.re_search(".+Hub") +┏━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexSearch(s, '.+Hub') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├─────────────────────────┤ +│ False │ +│ True │ +└─────────────────────────┘ +``` + +### re_split + +```python +re_split(pattern) +``` + +Split a string by a regular expression `pattern`. + +#### Parameters + +| Name | Type | Description | Default | +|------|-----------------------------------------|--------------------|-------| +| pattern | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Regular expression string to split by | *required* | + +#### Returns + +| Name | Type | Description | +|------|---------------------------------------|----------------------------| +| | [ArrayValue](%60letsql.vendor.ibis.expr.types.arrays.ArrayValue%60) | Array of strings from splitting by `pattern` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable(dict(s=["a.b", "b.....c", "c.........a", "def"])) +>>> t.s +┏━━━━━━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━━━━━━┩ +│ string │ +├─────────────┤ +│ a.b │ +│ b.....c │ +│ c.........a │ +│ def │ +└─────────────┘ +>>> t.s.re_split(r"\.+").name("splits") +┏━━━━━━━━━━━━━━━━━━━━━━┓ +┃ splits ┃ +┡━━━━━━━━━━━━━━━━━━━━━━┩ +│ array │ +├──────────────────────┤ +│ ['a', 'b'] │ +│ ['b', 'c'] │ +│ ['c', 'a'] │ +│ ['def'] │ +└──────────────────────┘ +``` + +### repeat + +```python +repeat(n) +``` + +Repeat a string `n` times. + +#### Parameters + +| Name | Type | Description | Default | +|-----|--------------------------------------------------|-----------|-------| +| n | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) | Number of repetitions | *required* | + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|--------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Repeated string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["a", "bb", "c"]}) +>>> t.s.repeat(5) +┏━━━━━━━━━━━━━━┓ +┃ Repeat(s, 5) ┃ +┡━━━━━━━━━━━━━━┩ +│ string │ +├──────────────┤ +│ aaaaa │ +│ bbbbbbbbbb │ +│ ccccc │ +└──────────────┘ +``` + +### replace + +```python +replace(pattern, replacement) +``` + +Replace each exact match of `pattern` with `replacement`. + +#### Parameters + +| Name | Type | Description | Default | +|---------|------------------------------------------|-------------|---------| +| pattern | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | String pattern | *required* | +| replacement | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | String replacement | *required* | + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|--------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Replaced string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "bac", "bca"]}) +>>> t.s.replace("b", "z") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringReplace(s, 'b', 'z') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├────────────────────────────┤ +│ azc │ +│ zac │ +│ zca │ +└────────────────────────────┘ +``` + +### reverse + +```python +reverse() +``` + +Reverse the characters of a string. + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|--------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Reversed string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "def", "ghi"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ abc │ +│ def │ +│ ghi │ +└────────┘ +>>> t.s.reverse() +┏━━━━━━━━━━━━┓ +┃ Reverse(s) ┃ +┡━━━━━━━━━━━━┩ +│ string │ +├────────────┤ +│ cba │ +│ fed │ +│ ihg │ +└────────────┘ +``` + +### right + +```python +right(nchars) +``` + +Return up to `nchars` from the end of each string. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------------------------------------|-----------------|------| +| nchars | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) | Maximum number of characters to return | *required* | + +#### Returns + +| Name | Type | Description | +|-------|-----------------------------------------------|------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Characters from the end | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "defg", "hijlk"]}) +>>> t.s.right(2) +┏━━━━━━━━━━━━━━━━┓ +┃ StrRight(s, 2) ┃ +┡━━━━━━━━━━━━━━━━┩ +│ string │ +├────────────────┤ +│ bc │ +│ fg │ +│ lk │ +└────────────────┘ +``` + +### rpad + +```python +rpad(length, pad=' ') +``` + +Pad `self` by truncating or padding on the right. + +#### Parameters + +| Name | Type | Description | Default | +|-----|--------------------------------------------------|------------|------| +| self | | String to pad | *required* | +| length | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) | Length of output string | *required* | +| pad | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Pad character | `' '` | + +#### Returns + +| Name | Type | Description | +|-------|-------------------------------------------------|----------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Right-padded string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "def", "ghij"]}) +>>> t.s.rpad(5, "-") +┏━━━━━━━━━━━━━━━━━┓ +┃ RPad(s, 5, '-') ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────┤ +│ abc-- │ +│ def-- │ +│ ghij- │ +└─────────────────┘ +``` + +### rstrip + +```python +rstrip() +``` + +Remove whitespace from the right side of string. + +#### Returns + +| Name | Type | Description | +|-------|------------------------------------------------|-----------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Right-stripped string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["\ta\t", "\nb\n", "\vc\t"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ \ta\t │ +│ \nb\n │ +│ \vc\t │ +└────────┘ +>>> t.s.rstrip() +┏━━━━━━━━━━━┓ +┃ RStrip(s) ┃ +┡━━━━━━━━━━━┩ +│ string │ +├───────────┤ +│ \ta │ +│ \nb │ +│ \vc │ +└───────────┘ +``` + +### split + +```python +split(delimiter) +``` + +Split as string on `delimiter`. + + +This API only works on backends with array support. + + +#### Parameters + +| Name | Type | Description | Default | +|-------|----------------------------------------------|------------|--------| +| delimiter | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Value to split by | *required* | + +#### Returns + +| Name | Type | Description | +|-------|-------------------------------------------|-----------------------| +| | [ArrayValue](%60letsql.vendor.ibis.expr.types.arrays.ArrayValue%60) | The string split by `delimiter` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"col": ["a,b,c", "d,e", "f"]}) +>>> t +┏━━━━━━━━┓ +┃ col ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ a,b,c │ +│ d,e │ +│ f │ +└────────┘ +>>> t.col.split(",") +┏━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringSplit(col, ',') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━┩ +│ array │ +├───────────────────────┤ +│ ['a', 'b', ... +1] │ +│ ['d', 'e'] │ +│ ['f'] │ +└───────────────────────┘ +``` + +### startswith + +```python +startswith(start) +``` + +Determine whether `self` starts with `start`. + +#### Parameters + +| Name | Type | Description | Default | +|------|-----------------------------------------------|-------------|--------| +| start | [str](%60str%60) \| [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | prefix to check for | *required* | + +#### Returns + +| Name | Type | Description | +|------|-------------------------------------|------------------------------| +| | [BooleanValue](%60letsql.vendor.ibis.expr.types.logical.BooleanValue%60) | Boolean indicating whether `self` starts with `start` | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["Ibis project", "GitHub"]}) +>>> t.s.startswith("Ibis") +┏━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StartsWith(s, 'Ibis') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────────────┤ +│ True │ +│ False │ +└───────────────────────┘ +``` + +### strip + +```python +strip() +``` + +Remove whitespace from left and right sides of a string. + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|--------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Stripped string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["\ta\t", "\nb\n", "\vc\t"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ \ta\t │ +│ \nb\n │ +│ \vc\t │ +└────────┘ +>>> t.s.strip() +┏━━━━━━━━━━┓ +┃ Strip(s) ┃ +┡━━━━━━━━━━┩ +│ string │ +├──────────┤ +│ a │ +│ b │ +│ c │ +└──────────┘ +``` + +### substr + +```python +substr(start, length=None) +``` + +Extract a substring. + +#### Parameters + +| Name | Type | Description | Default | +|----|---------------------------------------|-------------------------|-----| +| start | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) | First character to start splitting, indices start at 0 | *required* | +| length | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) \| None | Maximum length of each substring. If not supplied, searches the entire string | `None` | + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|--------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Found substring | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "defg", "hijlk"]}) +>>> t.s.substr(2) +┏━━━━━━━━━━━━━━━━━┓ +┃ Substring(s, 2) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────┤ +│ c │ +│ fg │ +│ jlk │ +└─────────────────┘ +``` + +### to_date + +```python +to_date(format_str) +``` + +### translate + +```python +translate(from_str, to_str) +``` + +Replace `from_str` characters in `self` characters in `to_str`. + +To avoid unexpected behavior, `from_str` should be shorter than +`to_str`. + +#### Parameters + +| Name | Type | Description | Default | +|-------|--------------------------------------|--------------------|--------| +| from_str | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Characters in `arg` to replace | *required* | +| to_str | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Characters to use for replacement | *required* | + +#### Returns + +| Name | Type | Description | +|-------|--------------------------------------------------|---------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Translated string | + +#### Examples + +```python +>>> import ibis +>>> table = ibis.table(dict(string_col="string")) +>>> result = table.string_col.translate("a", "b") +``` + +### upper + +```python +upper() +``` + +Convert string to all uppercase. + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------------|---------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Uppercase string | + +#### Examples + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["aaa", "A", "aa"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ aaa │ +│ A │ +│ aa │ +└────────┘ +>>> t.s.upper() +┏━━━━━━━━━━━━━━┓ +┃ Uppercase(s) ┃ +┡━━━━━━━━━━━━━━┩ +│ string │ +├──────────────┤ +│ AAA │ +│ A │ +│ AA │ +└──────────────┘ +``` + +### userinfo + +```python +userinfo() +``` + +Parse a URL and extract user info. + +#### Examples + +```python +>>> import ibis +>>> url = ibis.literal("https://user:pass@example.com:80/docs/books") +>>> result = url.userinfo() # user:pass +``` + +#### Returns + +| Name | Type | Description | +|-------|------------------------------------------------|------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | Extracted string value | diff --git a/docs/api-reference/expression-temporal.mdx b/docs/api-reference/expression-temporal.mdx new file mode 100644 index 00000000..ab998e2e --- /dev/null +++ b/docs/api-reference/expression-temporal.mdx @@ -0,0 +1,306 @@ +--- +title: 'Temporal expressions' +--- + +Dates, times, timestamps and intervals. + +# TimeValue + +```python +TimeValue(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [hour](#letsql.vendor.ibis.expr.types.temporal.TimeValue.hour) | Extract the hour component. | +| [microsecond](#letsql.vendor.ibis.expr.types.temporal.TimeValue.microsecond) | Extract the microsecond component. | +| [millisecond](#letsql.vendor.ibis.expr.types.temporal.TimeValue.millisecond) | Extract the millisecond component. | +| [minute](#letsql.vendor.ibis.expr.types.temporal.TimeValue.minute) | Extract the minute component. | +| [second](#letsql.vendor.ibis.expr.types.temporal.TimeValue.second) | Extract the second component. | +| [time](#letsql.vendor.ibis.expr.types.temporal.TimeValue.time) | Return the time component of the expression. | +| [truncate](#letsql.vendor.ibis.expr.types.temporal.TimeValue.truncate) | Truncate the expression to a time expression in units of `unit`. | + +### hour + +```python +hour() +``` + +Extract the hour component. + +### microsecond + +```python +microsecond() +``` + +Extract the microsecond component. + +### millisecond + +```python +millisecond() +``` + +Extract the millisecond component. + +### minute + +```python +minute() +``` + +Extract the minute component. + +### second + +```python +second() +``` + +Extract the second component. + +### time + +```python +time() +``` + +Return the time component of the expression. + +#### Returns + +| Name | Type | Description | +|-------|--------------------------------------------|---------------------| +| | [TimeValue](%60letsql.vendor.ibis.expr.types.temporal.TimeValue%60) | The time component of `self` | + +### truncate + +```python +truncate(unit) +``` + +Truncate the expression to a time expression in units of `unit`. + +Commonly used for time series resampling. + +#### Parameters + +| Name | Type | Description | Default | +|------|--------------------------------------------|---------------|--------| +| unit | [Literal](%60typing.Literal%60)\['h', 'm', 's', 'ms', 'us', 'ns'\] | The unit to truncate to | *required* | + +#### Returns + +| Name | Type | Description | +|-------|---------------------------------------------|--------------------| +| | [TimeValue](%60letsql.vendor.ibis.expr.types.temporal.TimeValue%60) | `self` truncated to `unit` | + +# DateValue + +```python +DateValue(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [day](#letsql.vendor.ibis.expr.types.temporal.DateValue.day) | Extract the day component. | +| [day_of_year](#letsql.vendor.ibis.expr.types.temporal.DateValue.day_of_year) | Extract the day of the year component. | +| [epoch_seconds](#letsql.vendor.ibis.expr.types.temporal.DateValue.epoch_seconds) | Extract UNIX epoch in seconds. | +| [month](#letsql.vendor.ibis.expr.types.temporal.DateValue.month) | Extract the month component. | +| [quarter](#letsql.vendor.ibis.expr.types.temporal.DateValue.quarter) | Extract the quarter component. | +| [truncate](#letsql.vendor.ibis.expr.types.temporal.DateValue.truncate) | Truncate date expression to units of `unit`. | +| [week_of_year](#letsql.vendor.ibis.expr.types.temporal.DateValue.week_of_year) | Extract the week of the year component. | +| [year](#letsql.vendor.ibis.expr.types.temporal.DateValue.year) | Extract the year component. | + +### day + +```python +day() +``` + +Extract the day component. + +### day_of_year + +```python +day_of_year() +``` + +Extract the day of the year component. + +### epoch_seconds + +```python +epoch_seconds() +``` + +Extract UNIX epoch in seconds. + +### month + +```python +month() +``` + +Extract the month component. + +### quarter + +```python +quarter() +``` + +Extract the quarter component. + +### truncate + +```python +truncate(unit) +``` + +Truncate date expression to units of `unit`. + +#### Parameters + +| Name | Type | Description | Default | +|------|-----------------------------------------|------------------|---------| +| unit | [Literal](%60typing.Literal%60)\['Y', 'Q', 'M', 'W', 'D'\] | Unit to truncate `arg` to | *required* | + +#### Returns + +| Name | Type | Description | +|-------|-------------------------------------------|-----------------------| +| | [DateValue](%60letsql.vendor.ibis.expr.types.temporal.DateValue%60) | Truncated date value expression | + +### week_of_year + +```python +week_of_year() +``` + +Extract the week of the year component. + +### year + +```python +year() +``` + +Extract the year component. + +# DayOfWeek + +```python +DayOfWeek(self, expr) +``` + +A namespace of methods for extracting day of week information. + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [full_name](#letsql.vendor.ibis.expr.types.temporal.DayOfWeek.full_name) | Get the name of the day of the week. | +| [index](#letsql.vendor.ibis.expr.types.temporal.DayOfWeek.index) | Get the index of the day of the week. | + +### full_name + +```python +full_name() +``` + +Get the name of the day of the week. + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------------|----------------------| +| | [StringValue](%60letsql.vendor.ibis.expr.types.strings.StringValue%60) | The name of the day of the week | + +### index + +```python +index() +``` + +Get the index of the day of the week. + + +Ibis follows the `pandas` convention for day numbering: Monday = 0 and Sunday = 6. + + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------------|-----------------------| +| | [IntegerValue](%60letsql.vendor.ibis.expr.types.numeric.IntegerValue%60) | The index of the day of the week. | + +# TimestampValue + +```python +TimestampValue(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [date](#letsql.vendor.ibis.expr.types.temporal.TimestampValue.date) | Return the date component of the expression. | +| [truncate](#letsql.vendor.ibis.expr.types.temporal.TimestampValue.truncate) | Truncate timestamp expression to units of `unit`. | + +### date + +```python +date() +``` + +Return the date component of the expression. + +#### Returns + +| Name | Type | Description | +|-------|--------------------------------------------|---------------------| +| | [DateValue](%60letsql.vendor.ibis.expr.types.temporal.DateValue%60) | The date component of `self` | + +### truncate + +```python +truncate(unit) +``` + +Truncate timestamp expression to units of `unit`. + +#### Parameters + +| Name | Type | Description | Default | +|-----|--------------------------------------------------|-----------|-------| +| unit | [Literal](%60typing.Literal%60)\['Y', 'Q', 'M', 'W', 'D', 'h', 'm', 's', 'ms', 'us', 'ns'\] | Unit to truncate to | *required* | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------------|--------------------| +| | [TimestampValue](%60letsql.vendor.ibis.expr.types.temporal.TimestampValue%60) | Truncated timestamp expression | + +# IntervalValue + +```python +IntervalValue(self, arg) +``` + +## Methods + +| Name | Description | +|------------------------------------|------------------------------------| +| [to_unit](#letsql.vendor.ibis.expr.types.temporal.IntervalValue.to_unit) | | + +### to_unit + +```python +to_unit(target_unit) +``` diff --git a/docs/api-reference/ml-api.mdx b/docs/api-reference/ml-api.mdx new file mode 100644 index 00000000..dbbfacdf --- /dev/null +++ b/docs/api-reference/ml-api.mdx @@ -0,0 +1,63 @@ +--- +title: ML Functions +--- + +# train_test_splits + +```python +train_test_splits( + table, + unique_key, + test_sizes, + num_buckets=10000, + random_seed=None, +) +``` + +Generates multiple train/test splits of an Ibis table for different test +sizes. + +This function splits an Ibis table into multiple subsets based on a +unique key or combination of keys and a list of test sizes. It uses a +hashing function to convert the unique key into an integer, then applies +a modulo operation to split the data into buckets. Each subset of data +is defined by a range of buckets determined by the cumulative sum of the +test sizes. + +#### Parameters + +| Name | Type | Description | Default | +|---|--------------|-----------------------------------------------------|---| +| table | [ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60) | The input Ibis table to be split. | *required* | +| unique_key | [str](%60str%60) \| [list](%60list%60)\[[str](%60str%60)\] | The column name(s) that uniquely identify each row in the table. This unique_key is used to create a deterministic split of the dataset through a hashing process. | *required* | +| test_sizes | [Iterable](%60typing.Iterable%60)\[[float](%60float%60)\] \| [float](%60float%60) | An iterable of floats representing the desired proportions for data splits. Each value should be between 0 and 1, and their sum must equal 1. The order of test sizes determines the order of the generated subsets. If float is passed it assumes that the value is for the test size and that a tradition tain test split of (1-test_size, test_size) is returned. | *required* | +| num_buckets | [int](%60int%60) | The number of buckets into which the data can be binned after being hashed (default is 10000). It controls how finely the data is divided during the split process. Adjusting num_buckets can affect the granularity and efficiency of the splitting operation, balancing between accuracy and computational efficiency. | `10000` | +| random_seed | [int](%60int%60) \| None | Seed for the random number generator. If provided, ensures reproducibility of the split (default is None). | `None` | + +#### Returns + +| Name | Type | Description | +|---|-------------------------------|--------------------------------------| +| | [Iterator](%60typing.Iterator%60)\[[ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60)\] | An iterator yielding Ibis table expressions, each representing a mutually exclusive subset of the original table based on the specified test sizes. | + +#### Raises + +| Name | Type | Description | +|-----|------------|--------------------------------------------------------| +| | [ValueError](%60ValueError%60) | If any value in `test_sizes` is not between 0 and 1. If `test_sizes` does not sum to 1. If `num_buckets` is not an integer greater than 1. | + +#### Examples + +```python +>>> import letsql as ls +>>> table = ls.memtable({"key": range(100), "value": range(100,200)}) +>>> unique_key = "key" +>>> test_sizes = [0.2, 0.3, 0.5] +>>> splits = ls.train_test_splits(table, unique_key, test_sizes, num_buckets=10, random_seed=42) +>>> for i, split_table in enumerate(splits): +... print(f"Split {i+1} size: {split_table.count().execute()}") +... print(split_table.execute()) +Split 1 size: 20 +Split 2 size: 30 +Split 3 size: 50 +``` diff --git a/docs/api-reference/toplevel-api.mdx b/docs/api-reference/toplevel-api.mdx new file mode 100644 index 00000000..17dfc439 --- /dev/null +++ b/docs/api-reference/toplevel-api.mdx @@ -0,0 +1,1485 @@ +--- +title: Data Functions +--- + +# param + +```python +param(type) +``` + +Create a deferred parameter of a given type. + +#### Parameters + +| Name | Type | Description | Default | +|----|-------------------------------------------|---------------------|-----| +| type | [Union](%60typing.Union%60)\[[dt](%60letsql.vendor.ibis.expr.datatypes%60).[DataType](%60letsql.vendor.ibis.expr.datatypes.DataType%60), [str](%60str%60)\] | The type of the unbound parameter, e.g., double, int64, date, etc. | *required* | + +#### Returns + +| Name | Type | Description | +|-------|-----------------------------------|-------------------------------| +| | [Scalar](%60letsql.vendor.ibis.expr.types.Scalar%60) | A scalar expression backend by a parameter | + +#### Examples + +```python +>>> from datetime import date +>>> import letsql +>>> start = letsql.param("date") +>>> t = letsql.memtable( +... { +... "date_col": [date(2013, 1, 1), date(2013, 1, 2), date(2013, 1, 3)], +... "value": [1.0, 2.0, 3.0], +... }, +... ) +>>> expr = t.filter(t.date_col >= start).value.sum() +>>> expr.execute(params={start: date(2013, 1, 1)}) +6.0 +>>> expr.execute(params={start: date(2013, 1, 2)}) +5.0 +>>> expr.execute(params={start: date(2013, 1, 3)}) +3.0 +``` + +# schema + +```python +schema(pairs=None, names=None, types=None) +``` + +Validate and return a [`Schema`](./schemas.qmd#ibis.expr.schema.Schema) +object. + +#### Parameters + +| Name | Type | Description | Default | +|---|-----------------------------------------|------------------------|----| +| pairs | [SchemaLike](%60letsql.vendor.ibis.expr.schema.SchemaLike%60) \| None | List or dictionary of name, type pairs. Mutually exclusive with `names` and `types` arguments. | `None` | +| names | [Iterable](%60collections.abc.Iterable%60)\[[str](%60str%60)\] \| None | Field names. Mutually exclusive with `pairs`. | `None` | +| types | [Iterable](%60collections.abc.Iterable%60)\[[str](%60str%60) \| [dt](%60letsql.vendor.ibis.expr.datatypes%60).[DataType](%60letsql.vendor.ibis.expr.datatypes.DataType%60)\] \| None | Field types. Mutually exclusive with `pairs`. | `None` | + +#### Returns + +| Name | Type | Description | +|---------|------------------------------------------------|----------------| +| | [Schema](%60letsql.vendor.ibis.expr.schema.Schema%60) | An ibis schema | + +#### Examples + +```python +>>> from letsql import schema +>>> sc = schema([("foo", "string"), ("bar", "int64"), ("baz", "boolean")]) +>>> sc = schema(names=["foo", "bar", "baz"], types=["string", "int64", "boolean"]) +>>> sc = schema(dict(foo="string")) # no-op +``` + +# table + +```python +table(schema=None, name=None, catalog=None, database=None) +``` + +Create a table literal or an abstract table without data. + +Ibis uses the word database to refer to a collection of tables, and the +word catalog to refer to a collection of databases. You can use a +combination of `catalog` and `database` to specify a hierarchical +location for table. + +#### Parameters + +| Name | Type | Description | Default | +|------|-------------------------------|-----------------------------|------| +| schema | [SchemaLike](%60letsql.vendor.ibis.expr.schema.SchemaLike%60) \| None | A schema for the table | `None` | +| name | [str](%60str%60) \| None | Name for the table. One is generated if this value is `None`. | `None` | +| catalog | [str](%60str%60) \| None | A collection of database. | `None` | +| database | [str](%60str%60) \| None | A collection of tables. Required if catalog is not `None`. | `None` | + +#### Returns + +| Name | Type | Description | +|---------|--------------------------------------------|-------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.Table%60) | A table expression | + +#### Examples + +Create a table with no data backing it + +```python +>>> import letsql +>>> letsql.options.interactive = False +>>> t = letsql.table(schema=dict(a="int", b="string"), name="t") +>>> t +UnboundTable: t + a int64 + b string +``` + +Create a table with no data backing it in a specific location + +```python +>>> import letsql +>>> letsql.options.interactive = False +>>> t = letsql.table(schema=dict(a="int"), name="t", catalog="cat", database="db") +>>> t +UnboundTable: cat.db.t + a int64 +``` + +# memtable + +```python +memtable(data, *, columns=None, schema=None, name=None) +``` + +Construct an ibis table expression from in-memory data. + +#### Parameters + +| Name | Type | Description | Default | +|---|-----------|--------------------------------------------------------|---| +| data | | A table-like object (`pandas.DataFrame`, `pyarrow.Table`, or `polars.DataFrame`), or any data accepted by the `pandas.DataFrame` constructor (e.g. a list of dicts). Note that ibis objects (e.g. `MapValue`) may not be passed in as part of `data` and will result in an error. Do not depend on the underlying storage type (e.g., pyarrow.Table), it’s subject to change across non-major releases. | *required* | +| columns | [Iterable](%60collections.abc.Iterable%60)\[[str](%60str%60)\] \| None | Optional [](%60typing.Iterable%60) of [](%60str%60) column names. If provided, must match the number of columns in `data`. | `None` | +| schema | [SchemaLike](%60letsql.vendor.ibis.expr.schema.SchemaLike%60) \| None | Optional [`Schema`](./schemas.qmd#ibis.expr.schema.Schema). The functions use `data` to infer a schema if not passed. | `None` | +| name | [str](%60str%60) \| None | Optional name of the table. | `None` | + +#### Returns + +| Name | Type | Description | +|-------|----------------------------------|--------------------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.Table%60) | A table expression backed by in-memory data. | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = False +>>> t = letsql.memtable([{"a": 1}, {"a": 2}]) +>>> t +InMemoryTable + data: + PandasDataFrameProxy: + a + 0 1 + 1 2 +``` + + +```python +>>> t = letsql.memtable([{"a": 1, "b": "foo"}, {"a": 2, "b": "baz"}]) +>>> t +InMemoryTable + data: + PandasDataFrameProxy: + a b + 0 1 foo + 1 2 baz +``` + +Create a table literal without column names embedded in the data and +pass `columns` + +```python +>>> t = letsql.memtable([(1, "foo"), (2, "baz")], columns=["a", "b"]) +>>> t +InMemoryTable + data: + PandasDataFrameProxy: + a b + 0 1 foo + 1 2 baz +``` + +Create a table literal without column names embedded in the data. Ibis +generates column names if none are provided. + +```python +>>> t = letsql.memtable([(1, "foo"), (2, "baz")]) +>>> t +InMemoryTable + data: + PandasDataFrameProxy: + col0 col1 + 0 1 foo + 1 2 baz +``` + +# desc + +```python +desc(expr) +``` + +Create a descending sort key from `expr` or column name. + +#### Parameters + +| Name | Type | Description | Default | +|-----|------------------------------------------|---------------------|------| +| expr | [ir](%60letsql.vendor.ibis.expr.types%60).[Column](%60letsql.vendor.ibis.expr.types.Column%60) \| [str](%60str%60) | The expression or column name to use for sorting | *required* | + +## See Also + +[`Value.desc()`](./expression-generic.qmd#ibis.expr.types.generic.Value.desc) + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.examples.penguins.fetch() +>>> t[["species", "year"]].order_by(letsql.desc("year")).head() +┏━━━━━━━━━┳━━━━━━━┓ +┃ species ┃ year ┃ +┡━━━━━━━━━╇━━━━━━━┩ +│ string │ int64 │ +├─────────┼───────┤ +│ Adelie │ 2009 │ +│ Adelie │ 2009 │ +│ Adelie │ 2009 │ +│ Adelie │ 2009 │ +│ Adelie │ 2009 │ +└─────────┴───────┘ +``` + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------------------------|----------| +| | [ir](%60letsql.vendor.ibis.expr.types%60).[ValueExpr](%60letsql.vendor.ibis.expr.types.ValueExpr%60) | An expression | + +# asc + +```python +asc(expr) +``` + +Create an ascending sort key from `asc` or column name. + +#### Parameters + +| Name | Type | Description | Default | +|-----|------------------------------------------|---------------------|------| +| expr | [ir](%60letsql.vendor.ibis.expr.types%60).[Column](%60letsql.vendor.ibis.expr.types.Column%60) \| [str](%60str%60) | The expression or column name to use for sorting | *required* | + +## See Also + +[`Value.asc()`](./expression-generic.qmd#ibis.expr.types.generic.Value.asc) + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.examples.penguins.fetch() +>>> t[["species", "year"]].order_by(letsql.asc("year")).head() +┏━━━━━━━━━┳━━━━━━━┓ +┃ species ┃ year ┃ +┡━━━━━━━━━╇━━━━━━━┩ +│ string │ int64 │ +├─────────┼───────┤ +│ Adelie │ 2007 │ +│ Adelie │ 2007 │ +│ Adelie │ 2007 │ +│ Adelie │ 2007 │ +│ Adelie │ 2007 │ +└─────────┴───────┘ +``` + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------------------------|----------| +| | [ir](%60letsql.vendor.ibis.expr.types%60).[ValueExpr](%60letsql.vendor.ibis.expr.types.ValueExpr%60) | An expression | + +# preceding + +```python +preceding(value) +``` + +# following + +```python +following(value) +``` + +# and\_ + +```python +and_(*predicates) +``` + +Combine multiple predicates using `&`. + +#### Parameters + +| Name | Type | Description | Default | +|-------|----------------------------------------------|--------------|------| +| predicates | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) | Boolean value expressions | `()` | + +#### Returns + +| Name | Type | Description | +|-----|---------------|-----------------------------------------------------| +| | [BooleanValue](%60BooleanValue%60) | A new predicate that evaluates to True if all composing predicates are True. If no predicates were provided, returns True. | + +# or\_ + +```python +or_(*predicates) +``` + +Combine multiple predicates using `|`. + +#### Parameters + +| Name | Type | Description | Default | +|-------|----------------------------------------------|--------------|------| +| predicates | [ir](%60letsql.vendor.ibis.expr.types%60).[BooleanValue](%60letsql.vendor.ibis.expr.types.BooleanValue%60) | Boolean value expressions | `()` | + +#### Returns + +| Name | Type | Description | +|-----|---------------|-----------------------------------------------------| +| | [BooleanValue](%60BooleanValue%60) | A new predicate that evaluates to True if any composing predicates are True. If no predicates were provided, returns False. | + +# random + +```python +random() +``` + +Return a random floating point number in the range \[0.0, 1.0). + +Similar to [](%60random.random%60) in the Python standard library. + +`ibis.random()` will generate a column of distinct random numbers even +if the same instance of `ibis.random()` is reused. + +When Ibis compiles an expression to SQL, each place where `random` is +used will render as a separate call to the given backend’s random number +generator. + +>>> import letsql r_a = letsql.random() \# doctest: +SKIP + +#### Returns + +| Name | Type | Description | +|---------|----------------------------------|------------------------------| +| | [FloatingScalar](%60FloatingScalar%60) | Random float value expression | + +# uuid + +```python +uuid() +``` + +Return a random UUID version 4 value. + +Similar to \[(’uuid.uuid4\`) in the Python standard library. + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> letsql.uuid() +UUID('e57e927b-aed2-483b-9140-dc32a26cad95') +``` + +#### Returns + +| Name | Type | Description | +|------|--------------------------------|------------------------------| +| | [UUIDScalar](%60UUIDScalar%60) | Random UUID value expression | + +# case + +```python +case() +``` + +Begin constructing a case expression. + +Use the `.when` method on the resulting object followed by `.end` to +create a complete case expression. + +#### Returns + +| Name | Type | Description | +|------|-----------------------------|--------------------------------------| +| | [SearchedCaseBuilder](%60SearchedCaseBuilder%60) | A builder object to use for constructing a case expression. | + +## See Also + +[`Value.case()`](./expression-generic.qmd#ibis.expr.types.generic.Value.case) + +#### Examples + +```python +>>> import letsql +>>> from letsql.vendor.ibis import _ +>>> letsql.options.interactive = True +>>> t = letsql.memtable( +... { +... "left": [1, 2, 3, 4], +... "symbol": ["+", "-", "*", "/"], +... "right": [5, 6, 7, 8], +... } +... ) +>>> t.mutate( +... result=( +... letsql.case() +... .when(_.symbol == "+", _.left + _.right) +... .when(_.symbol == "-", _.left - _.right) +... .when(_.symbol == "*", _.left * _.right) +... .when(_.symbol == "/", _.left / _.right) +... .end() +... ) +... ) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┳━━━━━━━━━┓ +┃ left ┃ symbol ┃ right ┃ result ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━╇━━━━━━━━━┩ +│ int64 │ string │ int64 │ float64 │ +├───────┼────────┼───────┼─────────┤ +│ 1 │ + │ 5 │ 6.0 │ +│ 2 │ - │ 6 │ -4.0 │ +│ 3 │ * │ 7 │ 21.0 │ +│ 4 │ / │ 8 │ 0.5 │ +└───────┴────────┴───────┴─────────┘ +``` + +# now + +```python +now() +``` + +Return an expression that will compute the current timestamp. + +#### Returns + +| Name | Type | Description | +|-------|----------------------------|-------------------------------------| +| | [TimestampScalar](%60TimestampScalar%60) | An expression representing the current timestamp. | + +# today + +```python +today() +``` + +Return an expression that will compute the current date. + +#### Returns + +| Name | Type | Description | +|--------|-------------------------|----------------------------------------| +| | [DateScalar](%60DateScalar%60) | An expression representing the current date. | + +# rank + +```python +rank() +``` + +Compute position of first element within each equal-value group in +sorted order. + +Equivalent to SQL’s `RANK()` window function. + +#### Returns + +| Name | Type | Description | +|------|----------------------------------|--------------| +| | [Int64Column](%60Int64Column%60) | The min rank | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(rank=letsql.rank().over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━┓ +┃ values ┃ rank ┃ +┡━━━━━━━━╇━━━━━━━┩ +│ int64 │ int64 │ +├────────┼───────┤ +│ 1 │ 0 │ +│ 1 │ 0 │ +│ 2 │ 2 │ +│ 2 │ 2 │ +│ 2 │ 2 │ +│ 3 │ 5 │ +└────────┴───────┘ +``` + +# dense_rank + +```python +dense_rank() +``` + +Position of first element within each group of equal values. + +Values are returned in sorted order and duplicate values are ignored. + +Equivalent to SQL’s `DENSE_RANK()`. + +#### Returns + +| Name | Type | Description | +|------|--------------------------------------|-------------| +| | [IntegerColumn](%60IntegerColumn%60) | The rank | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(rank=letsql.dense_rank().over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━┓ +┃ values ┃ rank ┃ +┡━━━━━━━━╇━━━━━━━┩ +│ int64 │ int64 │ +├────────┼───────┤ +│ 1 │ 0 │ +│ 1 │ 0 │ +│ 2 │ 1 │ +│ 2 │ 1 │ +│ 2 │ 1 │ +│ 3 │ 2 │ +└────────┴───────┘ +``` + +# percent_rank + +```python +percent_rank() +``` + +Return the relative rank of the values in the column. + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------|------------------| +| | [FloatingColumn](%60FloatingColumn%60) | The percent rank | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(pct_rank=letsql.percent_rank().over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━━━━┓ +┃ values ┃ pct_rank ┃ +┡━━━━━━━━╇━━━━━━━━━━┩ +│ int64 │ float64 │ +├────────┼──────────┤ +│ 1 │ 0.0 │ +│ 1 │ 0.0 │ +│ 2 │ 0.4 │ +│ 2 │ 0.4 │ +│ 2 │ 0.4 │ +│ 3 │ 1.0 │ +└────────┴──────────┘ +``` + +# cume_dist + +```python +cume_dist() +``` + +Return the cumulative distribution over a window. + +#### Returns + +| Name | Type | Description | +|---------|-----------------------------------|-----------------------------| +| | [FloatingColumn](%60FloatingColumn%60) | The cumulative distribution | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(dist=letsql.cume_dist().over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━━━━┓ +┃ values ┃ dist ┃ +┡━━━━━━━━╇━━━━━━━━━━┩ +│ int64 │ float64 │ +├────────┼──────────┤ +│ 1 │ 0.333333 │ +│ 1 │ 0.333333 │ +│ 2 │ 0.833333 │ +│ 2 │ 0.833333 │ +│ 2 │ 0.833333 │ +│ 3 │ 1.000000 │ +└────────┴──────────┘ +``` + +# ntile + +```python +ntile(buckets) +``` + +Return the integer number of a partitioning of the column values. + +#### Parameters + +| Name | Type | Description | Default | +|-----|----------------------------------------------|----------------|------| +| buckets | [int](%60int%60) \| [ir](%60letsql.vendor.ibis.expr.types%60).[IntegerValue](%60letsql.vendor.ibis.expr.types.IntegerValue%60) | Number of buckets to partition into | *required* | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(ntile=letsql.ntile(2).over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━┓ +┃ values ┃ ntile ┃ +┡━━━━━━━━╇━━━━━━━┩ +│ int64 │ int64 │ +├────────┼───────┤ +│ 1 │ 0 │ +│ 1 │ 0 │ +│ 2 │ 0 │ +│ 2 │ 1 │ +│ 2 │ 1 │ +│ 3 │ 1 │ +└────────┴───────┘ +``` + +# row_number + +```python +row_number() +``` + +Return an analytic function expression for the current row number. + + + +`row_number` is normalized across backends to start at 0 + + + +#### Returns + +| Name | Type | Description | +|--------|------------------------------|----------------------------------| +| | [IntegerColumn](%60IntegerColumn%60) | A column expression enumerating rows | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(rownum=letsql.row_number()) +┏━━━━━━━━┳━━━━━━━━┓ +┃ values ┃ rownum ┃ +┡━━━━━━━━╇━━━━━━━━┩ +│ int64 │ int64 │ +├────────┼────────┤ +│ 1 │ 0 │ +│ 2 │ 1 │ +│ 1 │ 2 │ +│ 2 │ 3 │ +│ 3 │ 4 │ +│ 2 │ 5 │ +└────────┴────────┘ +``` + +# read_csv + +```python +read_csv(sources, table_name=None, **kwargs) +``` + +Lazily load a CSV or set of CSVs. + +This function delegates to the `read_csv` method on the current default +backend (DuckDB or `ibis.config.default_backend`). + +#### Parameters + +| Name | Type | Description | Default | +|----|---------------------------|---------------------------------------|----| +| sources | [str](%60str%60) \| [Path](%60pathlib.Path%60) \| [Sequence](%60collections.abc.Sequence%60)\[[str](%60str%60) \| [Path](%60pathlib.Path%60)\] | A filesystem path or URL or list of same. Supports CSV and TSV files. | *required* | +| table_name | [str](%60str%60) \| None | A name to refer to the table. If not provided, a name will be generated. | `None` | +| kwargs | [Any](%60typing.Any%60) | Backend-specific keyword arguments for the file type. For the DuckDB backend used by default, please refer to: \* CSV/TSV: https://duckdb.org/docs/data/csv/overview.html#parameters. | `{}` | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------------|---------------------| +| | [ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60) | Table expression representing a file | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> lines = '''a,b +... 1,d +... 2, +... ,f +... ''' +>>> with open("/tmp/lines.csv", mode="w") as f: +... nbytes = f.write(lines) # nbytes is unused +>>> t = letsql.read_csv("/tmp/lines.csv") +>>> t +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ d │ +│ 2 │ NULL │ +│ NULL │ f │ +└───────┴────────┘ +``` + +# read_parquet + +```python +read_parquet(sources, table_name=None, **kwargs) +``` + +Lazily load a parquet file or set of parquet files. + +This function delegates to the `read_parquet` method on the current +default backend (DuckDB or `ibis.config.default_backend`). + +#### Parameters + +| Name | Type | Description | Default | +|----|----------------------------|------------------------------------|----| +| sources | [str](%60str%60) \| [Path](%60pathlib.Path%60) \| [Sequence](%60collections.abc.Sequence%60)\[[str](%60str%60) \| [Path](%60pathlib.Path%60)\] | A filesystem path or URL or list of same. | *required* | +| table_name | [str](%60str%60) \| None | A name to refer to the table. If not provided, a name will be generated. | `None` | +| kwargs | [Any](%60typing.Any%60) | Backend-specific keyword arguments for the file type. For the DuckDB backend used by default, please refer to: \* Parquet: https://duckdb.org/docs/data/parquet | `{}` | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------------|---------------------| +| | [ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60) | Table expression representing a file | + +#### Examples + +```python +>>> import letsql +>>> import pandas as pd +>>> letsql.options.interactive = True +>>> df = pd.DataFrame({"a": [1, 2, 3], "b": list("ghi")}) +>>> df + a b +0 1 g +1 2 h +2 3 i +>>> df.to_parquet("/tmp/data.parquet") +>>> t = letsql.read_parquet("/tmp/data.parquet") +>>> t +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ g │ +│ 2 │ h │ +│ 3 │ i │ +└───────┴────────┘ +``` + +# register + +```python +register(source, table_name=None, **kwargs) +``` + +# read_postgres + +```python +read_postgres(uri, table_name=None, **kwargs) +``` + +# read_sqlite + +```python +read_sqlite(path, *, table_name=None) +``` + +# union + +```python +union(table, *rest, distinct=False) +``` + +Compute the set union of multiple table expressions. + +The input tables must have identical schemas. + +#### Parameters + +| Name | Type | Description | Default | +|------|-------------------------------------------|----------------|-------| +| table | [ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60) | A table expression | *required* | +| \*rest | [ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60) | Additional table expressions | `()` | +| distinct | [bool](%60bool%60) | Only return distinct rows | `False` | + +#### Returns + +| Name | Type | Description | +|------|-------------------------------|-----------------------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.Table%60) | A new table containing the union of all input tables. | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t1 = letsql.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = letsql.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> letsql.union(t1, t2) # union all by default +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +│ 2 │ +│ 3 │ +└───────┘ +>>> letsql.union(t1, t2, distinct=True).order_by("a") +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +│ 3 │ +└───────┘ +``` + +# intersect + +```python +intersect(table, *rest, distinct=True) +``` + +Compute the set intersection of multiple table expressions. + +The input tables must have identical schemas. + +#### Parameters + +| Name | Type | Description | Default | +|------|-------------------------------------------|----------------|-------| +| table | [ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60) | A table expression | *required* | +| \*rest | [ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60) | Additional table expressions | `()` | +| distinct | [bool](%60bool%60) | Only return distinct rows | `True` | + +#### Returns + +| Name | Type | Description | +|------|-----------------------------|-------------------------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.Table%60) | A new table containing the intersection of all input tables. | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t1 = letsql.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = letsql.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> letsql.intersect(t1, t2) +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +└───────┘ +``` + +# difference + +```python +difference(table, *rest, distinct=True) +``` + +Compute the set difference of multiple table expressions. + +The input tables must have identical schemas. + +#### Parameters + +| Name | Type | Description | Default | +|-----|------------------------------------|-------------------------|------| +| table | [ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60) | A table expression | *required* | +| \*rest | [ir](%60letsql.vendor.ibis.expr.types%60).[Table](%60letsql.vendor.ibis.expr.types.Table%60) | Additional table expressions | `()` | +| distinct | [bool](%60bool%60) | Only diff distinct rows not occurring in the calling table | `True` | + +#### Returns + +| Name | Type | Description | +|------|-----------------------------|-------------------------------------| +| | [Table](%60letsql.vendor.ibis.expr.types.Table%60) | The rows present in `self` that are not present in `tables`. | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t1 = letsql.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = letsql.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> letsql.difference(t1, t2) +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +└───────┘ +``` + +# ifelse + +```python +ifelse(condition, true_expr, false_expr) +``` + +Construct a ternary conditional expression. + +#### Parameters + +| Name | Type | Description | Default | +|---------|--------------|------------------------------------------|---------| +| condition | [Any](%60typing.Any%60) | A boolean expression | *required* | +| true_expr | [Any](%60typing.Any%60) | Expression to return if `condition` evaluates to `True` | *required* | +| false_expr | [Any](%60typing.Any%60) | Expression to return if `condition` evaluates to `False` or `NULL` | *required* | + +#### Returns + +| Name | Type | Description | +|-----|-------------------------------------|------------------------------| +| Value | [ir](%60letsql.vendor.ibis.expr.types%60).[Value](%60letsql.vendor.ibis.expr.types.Value%60) | The value of `true_expr` if `condition` is `True` else `false_expr` | + +## See Also + +[`BooleanValue.ifelse()`](./expression-numeric.qmd#ibis.expr.types.logical.BooleanValue.ifelse) + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"condition": [True, False, True, None]}) +>>> letsql.ifelse(t.condition, "yes", "no") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ IfElse(condition, 'yes', 'no') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├────────────────────────────────┤ +│ yes │ +│ no │ +│ yes │ +│ no │ +└────────────────────────────────┘ +``` + +# coalesce + +```python +coalesce(*args) +``` + +Return the first non-null value from `args`. + +#### Parameters + +| Name | Type | Description | Default | +|-------|----------------|-----------------------------------------|---------| +| args | [Any](%60typing.Any%60) | Arguments from which to choose the first non-null value | `()` | + +#### Returns + +| Name | Type | Description | +|--------|-------------------------------------------|---------------------| +| | [Value](%60letsql.vendor.ibis.expr.types.Value%60) | Coalesced expression | + +## See Also + +[`Value.coalesce()`](#ibis.expr.types.generic.Value.coalesce) +[`Value.fill_null()`](#ibis.expr.types.generic.Value.fill_null) + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> letsql.coalesce(None, 4, 5) +4 +``` + +# greatest + +```python +greatest(*args) +``` + +Compute the largest value among the supplied arguments. + +#### Parameters + +| Name | Type | Description | Default | +|------|-------------------------|--------------------------|---------| +| args | [Any](%60typing.Any%60) | Arguments to choose from | `()` | + +#### Returns + +| Name | Type | Description | +|--------|--------------------------------------|---------------------------| +| | [Value](%60letsql.vendor.ibis.expr.types.Value%60) | Maximum of the passed arguments | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> letsql.greatest(None, 4, 5) +5 +``` + +# least + +```python +least(*args) +``` + +Compute the smallest value among the supplied arguments. + +#### Parameters + +| Name | Type | Description | Default | +|------|-------------------------|--------------------------|---------| +| args | [Any](%60typing.Any%60) | Arguments to choose from | `()` | + +#### Returns + +| Name | Type | Description | +|--------|--------------------------------------|---------------------------| +| | [Value](%60letsql.vendor.ibis.expr.types.Value%60) | Minimum of the passed arguments | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> letsql.least(None, 4, 5) +4 +``` + +# range + +```python +range(start, stop, step) +``` + +Generate a range of values. + +Integer ranges are supported, as well as timestamp ranges. + + + +`start` is inclusive and `stop` is exclusive, just like Python’s builtin +[range](range). + +When `step` equals 0, however, this function will return an empty array. + +Python’s `range` will raise an exception when `step` is zero. + + + +#### Parameters + +| Name | Type | Description | Default | +|-------|------|--------------------------------------|------------| +| start | | Lower bound of the range, inclusive. | *required* | +| stop | | Upper bound of the range, exclusive. | *required* | +| step | | Step value. Optional, defaults to 1. | *required* | + +#### Returns + +| Name | Type | Description | +|------|--------------------------------|--------------------| +| | [ArrayValue](%60ArrayValue%60) | An array of values | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +``` + +Range using only a stop argument + +```python +>>> letsql.range(5) +[0, 1, ... +3] +``` + +Simple range using start and stop + +```python +>>> letsql.range(1, 5) +[1, 2, ... +2] +``` + +Generate an empty range + +```python +>>> letsql.range(0) +[] +``` + +Negative step values are supported + +```python +>>> letsql.range(10, 4, -2) +[10, 8, ... +1] +``` + +`ibis.range` behaves the same as Python’s range … + +```python +>>> letsql.range(0, 7, -1) +[] +``` + +… except when the step is zero, in which case `ibis.range` returns an +empty array + +```python +>>> letsql.range(0, 5, 0) +[] +``` + +Because the resulting expression is array, you can unnest the values + +```python +>>> letsql.range(5).unnest().name("numbers") +┏━━━━━━━━━┓ +┃ numbers ┃ +┡━━━━━━━━━┩ +│ int8 │ +├─────────┤ +│ 0 │ +│ 1 │ +│ 2 │ +│ 3 │ +│ 4 │ +└─────────┘ +``` + +# timestamp + +```python +timestamp( + value_or_year, + month=None, + day=None, + hour=None, + minute=None, + second=None, + /, + timezone=None, +) +``` + +Construct a timestamp scalar or column. + +#### Parameters + +| Name | Type | Description | Default | +|-------|-----|-------------------------------------------------------|------| +| value_or_year | | Either a string value or `datetime.datetime` to coerce to a timestamp, or an integral value representing the timestamp year component. | *required* | +| month | | The timestamp month component; required if `value_or_year` is a year. | `None` | +| day | | The timestamp day component; required if `value_or_year` is a year. | `None` | +| hour | | The timestamp hour component; required if `value_or_year` is a year. | `None` | +| minute | | The timestamp minute component; required if `value_or_year` is a year. | `None` | +| second | | The timestamp second component; required if `value_or_year` is a year. | `None` | +| timezone | | The timezone name, or none for a timezone-naive timestamp. | `None` | + +#### Returns + +| Name | Type | Description | +|-------|-----------------------------------------------|------------------| +| | [TimestampValue](%60letsql.vendor.ibis.expr.types.TimestampValue%60) | A timestamp expression | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +``` + +Create a timestamp scalar from a string + +```python +>>> letsql.timestamp("2023-01-02T03:04:05") +Timestamp('2023-01-02 03:04:05') +``` + +Create a timestamp scalar from components + +```python +>>> letsql.timestamp(2023, 1, 2, 3, 4, 5) +Timestamp('2023-01-02 03:04:05') +``` + +Create a timestamp column from components + +```python +>>> t = letsql.memtable({"y": [2001, 2002], "m": [1, 4], "d": [2, 5], "h": [3, 6]}) +>>> letsql.timestamp(t.y, t.m, t.d, t.h, 0, 0).name("timestamp") +┏━━━━━━━━━━━━━━━━━━━━━┓ +┃ timestamp ┃ +┡━━━━━━━━━━━━━━━━━━━━━┩ +│ timestamp │ +├─────────────────────┤ +│ 2001-01-02 03:00:00 │ +│ 2002-04-05 06:00:00 │ +└─────────────────────┘ +``` + +# date + +```python +date(value_or_year, month=None, day=None, /) +``` + +# time + +```python +time(value_or_hour, minute=None, second=None, /) +``` + +Return a time literal if `value` is coercible to a time. + +#### Parameters + +| Name | Type | Description | Default | +|--------|-----|------------------------------------------------------|-------| +| value_or_hour | | Either a string value or `datetime.time` to coerce to a time, or an integral value representing the time hour component. | *required* | +| minute | | The time minute component; required if `value_or_hour` is an hour. | `None` | +| second | | The time second component; required if `value_or_hour` is an hour. | `None` | + +#### Returns + +| Name | Type | Description | +|--------|-----------------------------------------------|-----------------| +| | [TimeValue](%60letsql.vendor.ibis.expr.types.TimeValue%60) | A time expression | + +#### Examples + +```python +>>> import letsql +>>> letsql.options.interactive = True +``` + +Create a time scalar from a string + +```python +>>> letsql.time("01:02:03") +datetime.time(1, 2, 3) +``` + +Create a time scalar from hour, minute, and second + +```python +>>> letsql.time(1, 2, 3) +datetime.time(1, 2, 3) +``` + +Create a time column from hour, minute, and second + +```python +>>> t = letsql.memtable({"h": [1, 4], "m": [2, 5], "s": [3, 6]}) +>>> letsql.time(t.h, t.m, t.s).name("time") +┏━━━━━━━━━━┓ +┃ time ┃ +┡━━━━━━━━━━┩ +│ time │ +├──────────┤ +│ 01:02:03 │ +│ 04:05:06 │ +└──────────┘ +``` + +# interval + +```python +interval( + value=None, + unit='s', + *, + years=None, + quarters=None, + months=None, + weeks=None, + days=None, + hours=None, + minutes=None, + seconds=None, + milliseconds=None, + microseconds=None, + nanoseconds=None, +) +``` + +Return an interval literal expression. + +#### Parameters + +| Name | Type | Description | Default | +|---------|-------------------------------------------|--------------|-------| +| value | [int](%60int%60) \| [datetime](%60datetime%60).[timedelta](%60datetime.timedelta%60) \| None | Interval value. | `None` | +| unit | [str](%60str%60) | Unit of `value` | `'s'` | +| years | [int](%60int%60) \| None | Number of years | `None` | +| quarters | [int](%60int%60) \| None | Number of quarters | `None` | +| months | [int](%60int%60) \| None | Number of months | `None` | +| weeks | [int](%60int%60) \| None | Number of weeks | `None` | +| days | [int](%60int%60) \| None | Number of days | `None` | +| hours | [int](%60int%60) \| None | Number of hours | `None` | +| minutes | [int](%60int%60) \| None | Number of minutes | `None` | +| seconds | [int](%60int%60) \| None | Number of seconds | `None` | +| milliseconds | [int](%60int%60) \| None | Number of milliseconds | `None` | +| microseconds | [int](%60int%60) \| None | Number of microseconds | `None` | +| nanoseconds | [int](%60int%60) \| None | Number of nanoseconds | `None` | + +#### Returns + +| Name | Type | Description | +|------|----------------------------------------|------------------------| +| | [IntervalScalar](%60IntervalScalar%60) | An interval expression | + +# to_sql + +```python +to_sql(expr, pretty=True) +``` + +Return the formatted SQL string for an expression. + +#### Parameters + +| Name | Type | Description | Default | +|-----|------------------------------------------|------------------|-------| +| expr | [ir](%60letsql.vendor.ibis.expr.types%60).[Expr](%60letsql.vendor.ibis.expr.types.Expr%60) | Ibis expression. | *required* | +| pretty | [bool](%60bool%60) | Whether to use pretty formatting. | `True` | + +#### Returns + +| Name | Type | Description | +|------|------------------|----------------------| +| | [str](%60str%60) | Formatted SQL string | + +# execute + +```python +execute(expr, **kwargs) +``` + +# to_pyarrow_batches + +```python +to_pyarrow_batches(expr, *, chunk_size=1000000, **kwargs) +``` + +# to_pyarrow + +```python +to_pyarrow(expr, **kwargs) +``` + +# to_parquet + +```python +to_parquet(expr, path, params=None, **kwargs) +``` + +# get_plans + +```python +get_plans(expr) +``` diff --git a/docs/concepts.qmd b/docs/concepts.qmd deleted file mode 100644 index 4be44402..00000000 --- a/docs/concepts.qmd +++ /dev/null @@ -1,74 +0,0 @@ -# Concepts - -## What is LETSQL? - -LETSQL is a query engine with a pythonic dataframe interface, built on top of DataFusion that can be used to write multi-engine workflows. - -## What is not LETSQL? -Is not a dataframe library, while it provides a familiar pythonic dataframe interface, LETSQL is equipped with a query optimizer and can -provide in-situ and federated query processing. - -## Why LETSQL? - -By using LETSQL, you will: - -- Reduce errors thanks to a better Pythonic UX. -- Accelerate the development process by lowering the cognitive burden induced by using multiple interacting data systems. -- Gain in security by providing in-situ processing (the data does not move). -- Improve performance by avoiding data transfer and redundant operations. -- Reduce costs by easily swapping to the cheapest tool available. - -## What is Multi-Engine? - -What makes LETSQL stand-out against other Ibis backends, is that it can be use to build multi-engine workflows, by -multi-engine it means that it can an Ibis expression involving multiple backends in an optimal manner, segmenting the -expression and executing each part in-situ on the corresponding backend. - - -For the following example we are going to use an Ibis table from a Postgres connection and perform a join with an in-memory -pandas DataFrame. - -```{python} -#| code-summary: multi-engine example -import pathlib - -import ibis -import pandas as pd - -import letsql as ls - -ibis.options.interactive = True - -# create the letsql connection -con = ls.connect() - - -# create the Ibis Postgres connection -pg = ibis.postgres.connect( - host="localhost", - port=5432, - user="postgres", - password="postgres", - database="ibis_testing", -) - - -# register Postgres table -batting = con.register(pg.table("batting"), table_name="batting") - -# register csv file -df = pd.read_csv("https://raw.githubusercontent.com/ibis-project/testing-data/master/csv/awards_players.csv") -awards_players = con.register(df, table_name="awards_players") - -left = batting[batting.yearID == 2015] -right = awards_players[awards_players.lgID == "NL"].drop("yearID", "lgID").execute() - -left.join(right, ["playerID"], how="semi") -``` - - - - - - - diff --git a/docs/core_concepts.mdx b/docs/core_concepts.mdx new file mode 100644 index 00000000..cc932aac --- /dev/null +++ b/docs/core_concepts.mdx @@ -0,0 +1,285 @@ +--- +title: 'Core Concepts' +description: 'The core concepts to understand what is LetSQL' +--- + +# Caching System + +LetSQL provides a sophisticated caching system that enables efficient iterative development of ML pipelines. The caching system allows you to: + +- Cache results from upstream query engines +- Persist data locally or in remote storage +- Automatically invalidate cache when source data changes +- Chain caches across multiple engines + +## Storage Types + +LetSQL supports two main types of cache storage: + +### 1. SourceStorage + +- Automatically invalidates cache when upstream data changes +- Persistence depends on the source backend +- Supports both remote (Snowflake, Postgres) and in-process (pandas, DuckDB) backends + +```python + +``` + +### 2. SnapshotStorage + +- No automatic invalidation +- Ideal for one-off analyses +- Persistence depends on source backend + +### 3. ParquetCacheStorage + +- Special case of SourceStorage +- Caches results as Parquet files on local disk +- Uses source backend for writing +- Ensures durable persistence + +## Hashing Strategies + +Cache invalidation uses different hashing strategies based on the storage type: + +| Storage Type | Hash Components | +| --- | --- | +| In-Memory | Data bytes + Schema | +| Disk-Based | Query plan + Schema | +| Remote | Table metadata + Last modified time | + +## Key Benefits + +1. **Faster Iteration**: + - Reduce network calls to source systems + - Minimize recomputation of expensive operations + - Cache intermediate results for complex pipelines +2. **Declarative Integration**: + - Chain cache operations anywhere in the expression + - Transparent integration with existing pipelines + - Multiple storage options for different use cases +3. **Automatic Management**: + - Smart invalidation based on source changes + - No manual cache management required + - Efficient storage utilization +4. **Multi-Engine Support**: + - Cache data between different engines + - Optimize storage location for performance + - Flexible persistence options + +# Multi-Engine System + +LetSQL's multi-engine system enables seamless data movement between different query engines, allowing you to leverage the strengths of each engine while maintaining a unified workflow. + +## The `into_backend` Operator + +The core of LetSQL's multi-engine capability is the `into_backend` operator, which enables: + +- Transparent data movement between engines +- Zero-copy data transfer using Apache Arrow +- Automatic optimization of data placement + +```python + +``` + +## Supported Engines + +LetSQL currently supports: + +1. **In-Process Engines** + - DuckDB + - DataFusion + - Pandas +2. **Distributed Engines** + - Trino + - Snowflake + - BigQuery + +## Engine Selection Guidelines + +Choose engines based on their strengths: + +1. **DuckDB**: Local processing, AsOf joins, efficient file formats +2. **DataFusion**: Custom UDFs, streaming processing +3. **Trino**: Distributed queries, federation, security +4. **Snowflake/BigQuery**: Managed infrastructure, scalability + +## Data Transfer + +Data movement between engines is handled through: + +1. **Arrow Flight**: Zero-copy data transfer protocol +2. **Memory Management**: Automatic spilling to disk +3. **Batching**: Efficient chunk-based processing + +# Custom UD(X)F System + +LetSQL provides a powerful system for extending query engines with custom User-Defined X Functions (where X can be Scalar, Aggregate, or Window). + +## Types of UDXFs + +### 1. User-Defined Scalar Functions (UDF) + +- Basic transformations +- Feature engineering +- Metric calculations + +```python + +``` + +### 2. User-Defined Aggregate Functions (UDAF) + +- Complex metric computations +- Statistical aggregations +- Time-window calculations + +```python + +``` + +### 3. User-Defined Window Functions (UDWF) + +- Time-based comparisons +- Relative metrics +- Cohort analysis + +# Ephemeral Flight Service + +LetSQL's Ephemeral Flight Service provides a high-performance data transfer mechanism between engines using Apache Arrow Flight. Unlike traditional data transfer methods, this service: + +1. **Automatic Lifecycle Management** + + ```python + import letsql as ls + + with ls.flight_context() as flight: + + # Service cleaned up after context exit + + ``` + +2. **Zero-Copy Data Movement** + - Direct memory transfer between processes + - No serialization/deserialization overhead + - Efficient handling of large datasets +3. **Process Isolation** + - Separate processes for different engines + - Independent resource management + - Fault isolation +4. **Resource Management** +5. **Security Integration** + +## Implementation Details + +### Service Lifecycle + +1. **Startup** + - Dynamic port allocation + - Resource reservation + - Backend initialization +2. **Operation** + - Streaming data transfer + - Memory management + - Error handling +3. **Shutdown** + - Resource cleanup + - Connection termination + - Memory release + +# Comparison with Ibis + +While LetSQL is built on top of Ibis, it extends its capabilities in several key ways: + +## 1. Multi-Engine Execution + +Ibis: + +```python +# Ibis: Single backend at a time +conn = ibis.connect('duckdb://...') +table = conn.table('data') +result = table.execute() + +``` + +LetSQL: + +```python +result = ( + trino_table + .pipe(into_backend, duckdb) + .asof_join(other_table) + .pipe(into_backend, trino) + .execute() +) + +``` + +## 2. Caching Capabilities + +Ibis: + +```python +# Ibis: Backend-specific caching +table.cache().execute()# Creates temporary table ** Not Deferred** + +``` + +LetSQL: + +```python +# LetSQL: Flexible, cross-engine caching +(table + .cache(storage=ParquetCacheStorage())# Persistent cache + .pipe(into_backend, next_engine) + .execute()) + +``` + +## 3. UDF System + +Ibis: + +```python +# Ibis: Backend-specific UDF registration + +``` + +LetSQL: + +```python + +``` + +## 4. Data Transfer + +## 5. Pipeline Management + +Ibis: + +- Focus on query expression building +- Limited pipeline tooling +- Backend-specific optimizations + +LetSQL: + +- End-to-end pipeline support +- Built-in development tools +- Cross-engine optimization + +## Key Advantages over Ibis + +1. **Unified Experience** + - Consistent API across engines + - Seamless engine transitions + - Integrated caching system +2. **ML Focus** + - Built-in ML tooling + - Efficient feature engineering + - Model training integration +3. **Development Workflow** + - Interactive development support + - Caching for iteration \ No newline at end of file diff --git a/docs/development.mdx b/docs/development.mdx new file mode 100644 index 00000000..01887cf4 --- /dev/null +++ b/docs/development.mdx @@ -0,0 +1,19 @@ +--- +title: 'Getting Started' +--- + +# Installation guide + +```bash +pip install letsql +``` + +or use it with nix and drop in an IPython shell + +```bash +nix run github:letsql/letsql +``` + +# Quick start + +# First pipeline walk-through diff --git a/docs/docs.json b/docs/docs.json new file mode 100644 index 00000000..6409e54e --- /dev/null +++ b/docs/docs.json @@ -0,0 +1,87 @@ +{ + "$schema": "https://mintlify.com/docs.json", + "theme": "maple", + "name": "LETSQL Documentation", + "colors": { + "primary": "#7DF8FE", + "light": "#7DF8FE", + "dark": "#5CDBF7" + }, + "favicon": "/favicon.svg", + "navigation": { + "tabs": [ + { + "tab": "User Guide", + "groups": [ + { + "group": "User Guide", + "pages": [ + "overview", + "core_concepts", + "development" + ] + } + ] + }, + { + "tab": "API Reference", + "groups": [ + { + "group": "Expression API", + "pages": [ + "api-reference/expression-generic", + "api-reference/expression-numeric", + "api-reference/expression-relations", + "api-reference/expression-strings", + "api-reference/expression-temporal" + ] + }, + { + "group": "Functions API", + "pages": [ + "api-reference/toplevel-api", + "api-reference/ml-api" + ] + } + ] + } + ], + "global": { + "anchors": [ + { + "anchor": "Documentation", + "href": "https://docs.letsql.com/", + "icon": "book-open-cover" + }, + { + "anchor": "Community", + "href": "https://discord.gg/8Kma9DhcJG", + "icon": "slack" + }, + { + "anchor": "Blog", + "href": "https://www.letsql.com/posts", + "icon": "newspaper" + } + ] + } + }, + "logo": { + "light": "/logo/xorq_light.png", + "dark": "/logo/xorq_dark.png" + }, + "navbar": { + "links": [ + { + "label": "Support", + "href": "mailto:mesejo@letsql.com" + } + ] + }, + "footer": { + "socials": { + "github": "https://github.com/letsql/", + "linkedin": "https://www.linkedin.com/company/letsql/" + } + } +} diff --git a/docs/examples/mortgage.mdx b/docs/examples/mortgage.mdx new file mode 100644 index 00000000..6fb97cb6 --- /dev/null +++ b/docs/examples/mortgage.mdx @@ -0,0 +1 @@ +# Fannie Mae Mortgage Example diff --git a/docs/favicon.svg b/docs/favicon.svg new file mode 100644 index 00000000..0938bfe6 --- /dev/null +++ b/docs/favicon.svg @@ -0,0 +1,33 @@ + + + + + + + + + + + + + + + + + \ No newline at end of file diff --git a/docs/images/checks-passed.png b/docs/images/checks-passed.png new file mode 100644 index 00000000..3303c773 Binary files /dev/null and b/docs/images/checks-passed.png differ diff --git a/docs/images/hero-dark.png b/docs/images/hero-dark.png new file mode 100644 index 00000000..a61cbb12 Binary files /dev/null and b/docs/images/hero-dark.png differ diff --git a/docs/images/hero-light.png b/docs/images/hero-light.png new file mode 100644 index 00000000..68c712d6 Binary files /dev/null and b/docs/images/hero-light.png differ diff --git a/docs/images/logo.png b/docs/images/logo.png deleted file mode 100644 index 557549e4..00000000 Binary files a/docs/images/logo.png and /dev/null differ diff --git a/docs/index.qmd b/docs/index.qmd deleted file mode 100644 index 6ebdf4f9..00000000 --- a/docs/index.qmd +++ /dev/null @@ -1,12 +0,0 @@ -LETSQL - -Data processing library built on top of **Ibis** and **DataFusion** to write multi-engine data workflows. - -Key Features: - -- Simplicity: LETSQL leverages the Ibis expression system to offer a familiar dataframe experience -- Versatile: Use it for interactive rapid exploration, or to maintain complex ELT/ETL jobs, via DataFrame or SQL -- Speed: Provided by the usage of DataFusion a fast, embeddable, and extensible query engine written in Rust -- In-situ analysis: Natively query data in Postgres, Snowflake, BigQuery, or in any of the 20+ Ibis backends -- Query Federation: Access data from multiple systems within a single expression on a DataFrame. -- Open: Built on top of Ibis and DataFusion two independently governed open-source projects \ No newline at end of file diff --git a/docs/installation.qmd b/docs/installation.qmd deleted file mode 100644 index 82b90327..00000000 --- a/docs/installation.qmd +++ /dev/null @@ -1,16 +0,0 @@ -# Installation - -First, obtain at least Python 3.10 and make sure you have [created and activated](https://docs.python.org/3/library/venv.html) a virtual environment. -Using a virtual environment is strongly recommended, since it will help you to avoid clutter in your system-wide libraries. Once the requirements are met, you can use pip: - -```bash -pip install letsql -``` - -If the installation worked correctly, you should see the following after executing: - -```{python} -import letsql -letsql.__version__ -``` - diff --git a/docs/logo/dark.png b/docs/logo/dark.png new file mode 100644 index 00000000..7d8a2eb9 Binary files /dev/null and b/docs/logo/dark.png differ diff --git a/docs/logo/light.png b/docs/logo/light.png new file mode 100644 index 00000000..64685a71 Binary files /dev/null and b/docs/logo/light.png differ diff --git a/docs/logo/xorq_dark.png b/docs/logo/xorq_dark.png new file mode 100644 index 00000000..7c508df3 Binary files /dev/null and b/docs/logo/xorq_dark.png differ diff --git a/docs/logo/xorq_dark.svg b/docs/logo/xorq_dark.svg new file mode 100644 index 00000000..44a0fe9c --- /dev/null +++ b/docs/logo/xorq_dark.svg @@ -0,0 +1,55 @@ + + + + + + + + + + + + + + + xorq + + + + + + + + + \ No newline at end of file diff --git a/docs/logo/xorq_light.png 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Python-based machine learning processing tool designed to +simplify and accelerate your ML workflows. xorq brings together diverse data +engines like DuckDB, DataFusion, and Snowflake under one unified interface. + +Whether you're a data scientist or ML engineer, xorq empowers you to focus on +innovation rather than infrastructure. + +Hero Light + +Hero Dark + +### Features + +- **Expr (Ibis-Powered):** Define transformations using a familiar, Pythonic + API that is both expressive and backend-agnostic. +- **Cache:** Avoid redundant computations by materializing intermediate results + as Arrow RecordBatches, ensuring minimal re-computation. +- **Portable Python UDFs:** Write and serve Python UDFs seamlessly – + whether they’re used for aggregation, windowing, or transformation tasks. + +> **Mission Statement:** +> “Make data processing ergonomic, performant and reproducible.” + +## Getting Started + +The first step towards building declarative pipelines is to set-up your project. + + + Get your docs set up locally for easy development + + + Set-up your project, build and run + + + + +## Tutorials + +Dive in to learn more about how to use xorq. + + + + Learn key concpets in a brief tutorial + + + Declarative, multi-engine expressions for ML + + + Build your expr pipeline into executable and introspectable artifacts + + + Check out how to make it your own with extensible UDFs + + diff --git a/docs/quick-start.qmd b/docs/quick-start.qmd deleted file mode 100644 index 8aa6ef23..00000000 --- a/docs/quick-start.qmd +++ /dev/null @@ -1,30 +0,0 @@ -# Quick Start - -## Prerequisite - -Please start by following the [installation instructions](installation.qmd), and then install [pandas](https://pandas.pydata.org/docs/getting_started/install.html). - -## A simple example - -For this basic example let's create a `main.py` file with the following content: - -```{python} -#| eval: true -#| code-fold: false -#| code-summary: a letsql simple example -import pandas as pd - -import letsql as ls - -con = ls.connect() - -df = pd.DataFrame({"a": [1, 2, 3, 4, 5], "b": [2, 3, 4, 5, 6]}) -t = con.register(df, "frame") - -res = t.head(3).execute() -print(res) -``` - -If you run `python main.py` then your output should look like the above. - - \ No newline at end of file diff --git a/docs/reference/_sidebar.yml b/docs/reference/_sidebar.yml new file mode 100644 index 00000000..7a1b18f0 --- /dev/null +++ b/docs/reference/_sidebar.yml @@ -0,0 +1,15 @@ +website: + sidebar: + - contents: + - reference/index.qmd + - contents: + - reference/expression-relations.qmd + - reference/expression-generic.qmd + - reference/expression-numeric.qmd + - reference/expression-strings.qmd + - reference/expression-temporal.qmd + - reference/toplevel-api.qmd + - reference/ml-api.qmd + section: Expression API + id: reference + - id: dummy-sidebar diff --git a/docs/reference/expression-generic.qmd b/docs/reference/expression-generic.qmd new file mode 100644 index 00000000..50a1d3c4 --- /dev/null +++ b/docs/reference/expression-generic.qmd @@ -0,0 +1,1217 @@ +# Generic expressions + +Scalars and columns of any element type. + +# Value { #letsql.vendor.ibis.expr.types.generic.Value } + +```python +Value(self, arg) +``` + +Base class for a data generating expression having a known type. + +## Methods + +| Name | Description | +| --- | --- | +| [asc](#letsql.vendor.ibis.expr.types.generic.Value.asc) | Sort an expression ascending. | +| [cast](#letsql.vendor.ibis.expr.types.generic.Value.cast) | Cast expression to indicated data type. | +| [coalesce](#letsql.vendor.ibis.expr.types.generic.Value.coalesce) | Return the first non-null value from `args`. | +| [collect](#letsql.vendor.ibis.expr.types.generic.Value.collect) | Aggregate this expression's elements into an array. | +| [identical_to](#letsql.vendor.ibis.expr.types.generic.Value.identical_to) | Return whether this expression is identical to other. | +| [isin](#letsql.vendor.ibis.expr.types.generic.Value.isin) | Check whether this expression's values are in `values`. | +| [isnull](#letsql.vendor.ibis.expr.types.generic.Value.isnull) | Return whether this expression is NULL. | +| [name](#letsql.vendor.ibis.expr.types.generic.Value.name) | Rename an expression to `name`. | +| [notnull](#letsql.vendor.ibis.expr.types.generic.Value.notnull) | Return whether this expression is not NULL. | +| [nullif](#letsql.vendor.ibis.expr.types.generic.Value.nullif) | Set values to null if they equal the values `null_if_expr`. | +| [try_cast](#letsql.vendor.ibis.expr.types.generic.Value.try_cast) | Try cast expression to indicated data type. | + +### asc { #letsql.vendor.ibis.expr.types.generic.Value.asc } + +```python +asc(nulls_first=False) +``` + +Sort an expression ascending. + +### cast { #letsql.vendor.ibis.expr.types.generic.Value.cast } + +```python +cast(target_type) +``` + +Cast expression to indicated data type. + +Similar to `pandas.Series.astype`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|-------------|---------------------|------------------------------------------------------------------------------------|------------| +| target_type | [Any](`typing.Any`) | Type to cast to. Anything accepted by [`ibis.dtype()`](./datatypes.qmd#ibis.dtype) | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------|-------------------| +| | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) | Casted expression | + +#### See Also {.doc-section .doc-section-see-also} + +[`Value.try_cast()`](./expression-generic.qmd#ibis.expr.types.generic.Value.try_cast) +[`ibis.dtype()`](./datatypes.qmd#ibis.dtype) + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> x = ibis.examples.penguins.fetch()["bill_depth_mm"] +>>> x +┏━━━━━━━━━━━━━━━┓ +┃ bill_depth_mm ┃ +┡━━━━━━━━━━━━━━━┩ +│ float64 │ +├───────────────┤ +│ 18.7 │ +│ 17.4 │ +│ 18.0 │ +│ NULL │ +│ 19.3 │ +│ 20.6 │ +│ 17.8 │ +│ 19.6 │ +│ 18.1 │ +│ 20.2 │ +│ … │ +└───────────────┘ +``` + +python's built-in types can be used + +```python +>>> x.cast(int) +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ Cast(bill_depth_mm, int64) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ +├────────────────────────────┤ +│ 19 │ +│ 17 │ +│ 18 │ +│ NULL │ +│ 19 │ +│ 21 │ +│ 18 │ +│ 20 │ +│ 18 │ +│ 20 │ +│ … │ +└────────────────────────────┘ +``` + +or string names + +```python +>>> x.cast("uint16") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ Cast(bill_depth_mm, uint16) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ uint16 │ +├─────────────────────────────┤ +│ 19 │ +│ 17 │ +│ 18 │ +│ NULL │ +│ 19 │ +│ 21 │ +│ 18 │ +│ 20 │ +│ 18 │ +│ 20 │ +│ … │ +└─────────────────────────────┘ +``` + +If you make an illegal cast, you won't know until the backend actually +executes it. Consider [`.try_cast()`](#ibis.expr.types.generic.Value.try_cast). + +```python +>>> ibis.literal("a string").cast("int64") + +``` + +### coalesce { #letsql.vendor.ibis.expr.types.generic.Value.coalesce } + +```python +coalesce(*args) +``` + +Return the first non-null value from `args`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------|---------------------------------------------------------|-----------| +| args | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) | Arguments from which to choose the first non-null value | `()` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------|----------------------| +| | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) | Coalesced expression | + +#### See Also {.doc-section .doc-section-see-also} + +[`ibis.coalesce()`](./expression-generic.qmd#ibis.coalesce) +[`Value.fill_null()`](./expression-generic.qmd#ibis.expr.types.generic.Value.fill_null) + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.coalesce(None, 4, 5).name("x") +x: Coalesce(...) +``` + +### collect { #letsql.vendor.ibis.expr.types.generic.Value.collect } + +```python +collect(where=None, order_by=None, include_null=False) +``` + +Aggregate this expression's elements into an array. + +This function is called `array_agg`, `list_agg`, or `list` in other systems. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------------|------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | An optional filter expression. If provided, only rows where `where` is `True` will be included in the aggregate. | `None` | +| order_by | [Any](`typing.Any`) | An ordering key (or keys) to use to order the rows before aggregating. If not provided, the order of the items in the result is undefined and backend specific. | `None` | +| include_null | [bool](`bool`) | Whether to include null values when performing this aggregation. Set to `True` to include nulls in the result. | `False` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|-------------------------------------------------------------------|-----------------| +| | [ArrayScalar](`letsql.vendor.ibis.expr.types.arrays.ArrayScalar`) | Collected array | + +#### Examples {.doc-section .doc-section-examples} + +Basic collect usage + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"key": list("aaabb"), "value": [1, 2, 3, 4, 5]}) +>>> t +┏━━━━━━━━┳━━━━━━━┓ +┃ key ┃ value ┃ +┡━━━━━━━━╇━━━━━━━┩ +│ string │ int64 │ +├────────┼───────┤ +│ a │ 1 │ +│ a │ 2 │ +│ a │ 3 │ +│ b │ 4 │ +│ b │ 5 │ +└────────┴───────┘ +>>> t.value.collect() +┌────────────────┐ +│ [1, 2, ... +3] │ +└────────────────┘ +>>> type(t.value.collect()) + +``` + +Collect elements per group + +```python +>>> t.group_by("key").agg(v=lambda t: t.value.collect()).order_by("key") +┏━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━┓ +┃ key ┃ v ┃ +┡━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ array │ +├────────┼──────────────────────┤ +│ a │ [1, 2, ... +1] │ +│ b │ [4, 5] │ +└────────┴──────────────────────┘ +``` + +Collect elements per group using a filter + +```python +>>> t.group_by("key").agg(v=lambda t: t.value.collect(where=t.value > 1)).order_by("key") +┏━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━┓ +┃ key ┃ v ┃ +┡━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ array │ +├────────┼──────────────────────┤ +│ a │ [2, 3] │ +│ b │ [4, 5] │ +└────────┴──────────────────────┘ +``` + +### identical_to { #letsql.vendor.ibis.expr.types.generic.Value.identical_to } + +```python +identical_to(other) +``` + +Return whether this expression is identical to other. + +Corresponds to `IS NOT DISTINCT FROM` in SQL. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------|--------------------------|------------| +| other | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) | Expression to compare to | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|------------------------------------------------------| +| | [BooleanValue](`letsql.vendor.ibis.expr.types.logical.BooleanValue`) | Whether this expression is not distinct from `other` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> one = ibis.literal(1) +>>> two = ibis.literal(2) +>>> two.identical_to(one + one) +┌──────┐ +│ True │ +└──────┘ +``` + +### isin { #letsql.vendor.ibis.expr.types.generic.Value.isin } + +```python +isin(values) +``` + +Check whether this expression's values are in `values`. + +`NULL` values are propagated in the output. See examples for details. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------|------------| +| values | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) \| [Sequence](`collections.abc.Sequence`)\[[Value](`letsql.vendor.ibis.expr.types.generic.Value`)\] | Values or expression to check for membership | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|----------------------------------| +| | [BooleanValue](`letsql.vendor.ibis.expr.types.logical.BooleanValue`) | Expression indicating membership | + +#### See Also {.doc-section .doc-section-see-also} + +[`Value.notin()`](./expression-generic.qmd#ibis.expr.types.generic.Value.notin) + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"a": [1, 2, 3], "b": [2, 3, 4]}) +>>> t +┏━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━┩ +│ int64 │ int64 │ +├───────┼───────┤ +│ 1 │ 2 │ +│ 2 │ 3 │ +│ 3 │ 4 │ +└───────┴───────┘ +``` + +Check against a literal sequence of values + +```python +>>> t.a.isin([1, 2]) +┏━━━━━━━━━━━━━━━━━━━━━┓ +┃ InValues(a, (1, 2)) ┃ +┡━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├─────────────────────┤ +│ True │ +│ True │ +│ False │ +└─────────────────────┘ +``` + +Check against a derived expression + +```python +>>> t.a.isin(t.b + 1) +┏━━━━━━━━━━━━━━━┓ +┃ InSubquery(a) ┃ +┡━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────┤ +│ False │ +│ False │ +│ True │ +└───────────────┘ +``` + +Check against a column from a different table + +```python +>>> t2 = ibis.memtable({"x": [99, 2, 99]}) +>>> t.a.isin(t2.x) +┏━━━━━━━━━━━━━━━┓ +┃ InSubquery(a) ┃ +┡━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────┤ +│ False │ +│ True │ +│ False │ +└───────────────┘ +``` + +`NULL` behavior + +```python +>>> t = ibis.memtable({"x": [1, 2]}) +>>> t.x.isin([1, None]) +┏━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ InValues(x, (1, None)) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├────────────────────────┤ +│ True │ +│ NULL │ +└────────────────────────┘ +>>> t = ibis.memtable({"x": [1, None, 2]}) +>>> t.x.isin([1]) +┏━━━━━━━━━━━━━━━━━━━┓ +┃ InValues(x, (1,)) ┃ +┡━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────────┤ +│ True │ +│ NULL │ +│ False │ +└───────────────────┘ +>>> t.x.isin([3]) +┏━━━━━━━━━━━━━━━━━━━┓ +┃ InValues(x, (3,)) ┃ +┡━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────────┤ +│ False │ +│ NULL │ +│ False │ +└───────────────────┘ +``` + +### isnull { #letsql.vendor.ibis.expr.types.generic.Value.isnull } + +```python +isnull() +``` + +Return whether this expression is NULL. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch().limit(5) +>>> t.bill_depth_mm +┏━━━━━━━━━━━━━━━┓ +┃ bill_depth_mm ┃ +┡━━━━━━━━━━━━━━━┩ +│ float64 │ +├───────────────┤ +│ 18.7 │ +│ 17.4 │ +│ 18.0 │ +│ NULL │ +│ 19.3 │ +└───────────────┘ +>>> t.bill_depth_mm.isnull() +┏━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ IsNull(bill_depth_mm) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────────────┤ +│ False │ +│ False │ +│ False │ +│ True │ +│ False │ +└───────────────────────┘ +``` + +### name { #letsql.vendor.ibis.expr.types.generic.Value.name } + +```python +name(name) +``` + +Rename an expression to `name`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------|--------------------------------|------------| +| name | | The new name of the expression | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------|-------------------------| +| | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) | `self` with name `name` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"a": [1, 2]}, name="t") +>>> t.a +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t.a.name("b") +┏━━━━━━━┓ +┃ b ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +``` + +### notnull { #letsql.vendor.ibis.expr.types.generic.Value.notnull } + +```python +notnull() +``` + +Return whether this expression is not NULL. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch().limit(5) +>>> t.bill_depth_mm +┏━━━━━━━━━━━━━━━┓ +┃ bill_depth_mm ┃ +┡━━━━━━━━━━━━━━━┩ +│ float64 │ +├───────────────┤ +│ 18.7 │ +│ 17.4 │ +│ 18.0 │ +│ NULL │ +│ 19.3 │ +└───────────────┘ +>>> t.bill_depth_mm.notnull() +┏━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ NotNull(bill_depth_mm) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├────────────────────────┤ +│ True │ +│ True │ +│ True │ +│ False │ +│ True │ +└────────────────────────┘ +``` + +### nullif { #letsql.vendor.ibis.expr.types.generic.Value.nullif } + +```python +nullif(null_if_expr) +``` + +Set values to null if they equal the values `null_if_expr`. + +Commonly used to avoid divide-by-zero problems by replacing zero with +`NULL` in the divisor. + +Equivalent to `(self == null_if_expr).ifelse(ibis.null(), self)`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------------|--------------------------------------------------------|--------------------------------------------------|------------| +| null_if_expr | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) | Expression indicating what values should be NULL | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------|------------------| +| | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) | Value expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> vals = ibis.examples.penguins.fetch().head(5).sex +>>> vals +┏━━━━━━━━┓ +┃ sex ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ male │ +│ female │ +│ female │ +│ NULL │ +│ female │ +└────────┘ +>>> vals.nullif("male") +┏━━━━━━━━━━━━━━━━━━━━━┓ +┃ NullIf(sex, 'male') ┃ +┡━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────────┤ +│ NULL │ +│ female │ +│ female │ +│ NULL │ +│ female │ +└─────────────────────┘ +``` + +### try_cast { #letsql.vendor.ibis.expr.types.generic.Value.try_cast } + +```python +try_cast(target_type) +``` + +Try cast expression to indicated data type. + +If the cast fails for a row, the value is returned +as null or NaN depending on target_type and backend behavior. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|-------------|---------------------|----------------------------------------------------------------------------------------|------------| +| target_type | [Any](`typing.Any`) | Type to try cast to. Anything accepted by [`ibis.dtype()`](./datatypes.qmd#ibis.dtype) | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------|-------------------| +| | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) | Casted expression | + +#### See Also {.doc-section .doc-section-see-also} + +[`Value.cast()`](./expression-generic.qmd#ibis.expr.types.generic.Value.cast) +[`ibis.dtype()`](./datatypes.qmd#ibis.dtype) + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> from letsql.vendor.ibis import _ +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"numbers": [1, 2, 3, 4], "strings": ["1.0", "2", "hello", "world"]}) +>>> t +┏━━━━━━━━━┳━━━━━━━━━┓ +┃ numbers ┃ strings ┃ +┡━━━━━━━━━╇━━━━━━━━━┩ +│ int64 │ string │ +├─────────┼─────────┤ +│ 1 │ 1.0 │ +│ 2 │ 2 │ +│ 3 │ hello │ +│ 4 │ world │ +└─────────┴─────────┘ +>>> t = t.mutate(numbers_to_strings=_.numbers.try_cast("string")) +>>> t = t.mutate(strings_to_numbers=_.strings.try_cast("int")) +>>> t +┏━━━━━━━━━┳━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━┓ +┃ numbers ┃ strings ┃ numbers_to_strings ┃ strings_to_numbers ┃ +┡━━━━━━━━━╇━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ string │ string │ int64 │ +├─────────┼─────────┼────────────────────┼────────────────────┤ +│ 1 │ 1.0 │ 1 │ 1 │ +│ 2 │ 2 │ 2 │ 2 │ +│ 3 │ hello │ 3 │ NULL │ +│ 4 │ world │ 4 │ NULL │ +└─────────┴─────────┴────────────────────┴────────────────────┘ +``` + +# Scalar { #letsql.vendor.ibis.expr.types.generic.Scalar } + +```python +Scalar(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [as_table](#letsql.vendor.ibis.expr.types.generic.Scalar.as_table) | Promote the scalar expression to a table. | + +### as_table { #letsql.vendor.ibis.expr.types.generic.Scalar.as_table } + +```python +as_table() +``` + +Promote the scalar expression to a table. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------|--------------------| +| | [Table](`letsql.vendor.ibis.expr.types.joins.Table`) | A table expression | + +#### Examples {.doc-section .doc-section-examples} + +Promote an aggregation to a table + +```python +>>> import ibis +>>> import ibis.expr.types as ir +>>> t = ibis.table(dict(a="str"), name="t") +>>> expr = t.a.length().sum().name("len").as_table() +>>> isinstance(expr, ir.Table) +True +``` + +Promote a literal value to a table + +```python +>>> import ibis.expr.types as ir +>>> lit = ibis.literal(1).name("a").as_table() +>>> isinstance(lit, ir.Table) +True +``` + +# Column { #letsql.vendor.ibis.expr.types.generic.Column } + +```python +Column(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [approx_median](#letsql.vendor.ibis.expr.types.generic.Column.approx_median) | Return an approximate of the median of `self`. | +| [approx_nunique](#letsql.vendor.ibis.expr.types.generic.Column.approx_nunique) | Return the approximate number of distinct elements in `self`. | +| [arbitrary](#letsql.vendor.ibis.expr.types.generic.Column.arbitrary) | Select an arbitrary value in a column. | +| [count](#letsql.vendor.ibis.expr.types.generic.Column.count) | Compute the number of rows in an expression. | +| [first](#letsql.vendor.ibis.expr.types.generic.Column.first) | Return the first value of a column. | +| [lag](#letsql.vendor.ibis.expr.types.generic.Column.lag) | Return the row located at `offset` rows **before** the current row. | +| [last](#letsql.vendor.ibis.expr.types.generic.Column.last) | Return the last value of a column. | +| [lead](#letsql.vendor.ibis.expr.types.generic.Column.lead) | Return the row located at `offset` rows **after** the current row. | +| [max](#letsql.vendor.ibis.expr.types.generic.Column.max) | Return the maximum of a column. | +| [median](#letsql.vendor.ibis.expr.types.generic.Column.median) | Return the median of the column. | +| [min](#letsql.vendor.ibis.expr.types.generic.Column.min) | Return the minimum of a column. | +| [nth](#letsql.vendor.ibis.expr.types.generic.Column.nth) | Return the `n`th value (0-indexed) over a window. | +| [nunique](#letsql.vendor.ibis.expr.types.generic.Column.nunique) | Compute the number of distinct rows in an expression. | + +### approx_median { #letsql.vendor.ibis.expr.types.generic.Column.approx_median } + +```python +approx_median(where=None) +``` + +Return an approximate of the median of `self`. + +::: {.callout-note} +## The result may or may not be exact + +Whether the result is an approximation depends on the backend. + +::: {.callout-warning} +## Do not depend on the results being exact +::: + +::: + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|-----------------------------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter in values when `where` is `True` | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|------------------------------------------| +| | [Scalar](`letsql.vendor.ibis.expr.types.generic.Scalar`) | An approximation of the median of `self` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.approx_median() +┌────────┐ +│ 4030.0 │ +└────────┘ +>>> t.body_mass_g.approx_median(where=t.species == "Chinstrap") +┌────────┐ +│ 3700.0 │ +└────────┘ +``` + +### approx_nunique { #letsql.vendor.ibis.expr.types.generic.Column.approx_nunique } + +```python +approx_nunique(where=None) +``` + +Return the approximate number of distinct elements in `self`. + +::: {.callout-note} +## The result may or may not be exact + +Whether the result is an approximation depends on the backend. + +::: {.callout-warning} +## Do not depend on the results being exact +::: + +::: + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|-----------------------------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter in values when `where` is `True` | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|---------------------------------------------------------| +| | [Scalar](`letsql.vendor.ibis.expr.types.generic.Scalar`) | An approximate count of the distinct elements of `self` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.approx_nunique() +┌────┐ +│ 92 │ +└────┘ +>>> t.body_mass_g.approx_nunique(where=t.species == "Adelie") +┌────┐ +│ 61 │ +└────┘ +``` + +### arbitrary { #letsql.vendor.ibis.expr.types.generic.Column.arbitrary } + +```python +arbitrary(where=None, how=None) +``` + +Select an arbitrary value in a column. + +Returns an arbitrary (nondeterministic, backend-specific) value from +the column. The value will be non-NULL, except if the column is empty +or all values are NULL. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|---------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | A filter expression | `None` | +| how | [Any](`typing.Any`) | DEPRECATED | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|---------------| +| | [Scalar](`letsql.vendor.ibis.expr.types.generic.Scalar`) | An expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"a": [1, 2, 2], "b": list("aaa"), "c": [4.0, 4.1, 4.2]}) +>>> t +┏━━━━━━━┳━━━━━━━━┳━━━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━━━┩ +│ int64 │ string │ float64 │ +├───────┼────────┼─────────┤ +│ 1 │ a │ 4.0 │ +│ 2 │ a │ 4.1 │ +│ 2 │ a │ 4.2 │ +└───────┴────────┴─────────┘ +>>> t.group_by("a").agg(arb=t.b.arbitrary(), c=t.c.sum()).order_by("a") +┏━━━━━━━┳━━━━━━━━┳━━━━━━━━━┓ +┃ a ┃ arb ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━━━┩ +│ int64 │ string │ float64 │ +├───────┼────────┼─────────┤ +│ 1 │ a │ 4.0 │ +│ 2 │ a │ 8.3 │ +└───────┴────────┴─────────┘ +``` + +### count { #letsql.vendor.ibis.expr.types.generic.Column.count } + +```python +count(where=None) +``` + +Compute the number of rows in an expression. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|-------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter expression | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|-------------------------------------| +| | [IntegerScalar](`letsql.vendor.ibis.expr.types.numeric.IntegerScalar`) | Number of elements in an expression | + +### first { #letsql.vendor.ibis.expr.types.generic.Column.first } + +```python +first(where=None, order_by=None, include_null=False) +``` + +Return the first value of a column. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------------|------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | An optional filter expression. If provided, only rows where `where` is `True` will be included in the aggregate. | `None` | +| order_by | [Any](`typing.Any`) | An ordering key (or keys) to use to order the rows before aggregating. If not provided, the meaning of `first` is undefined and will be backend specific. | `None` | +| include_null | [bool](`bool`) | Whether to include null values when performing this aggregation. Set to `True` to include nulls in the result. | `False` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"chars": ["a", "b", "c", "d"]}) +>>> t +┏━━━━━━━━┓ +┃ chars ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ a │ +│ b │ +│ c │ +│ d │ +└────────┘ +>>> t.chars.first() +┌───┐ +│ a │ +└───┘ +>>> t.chars.first(where=t.chars != "a") +┌───┐ +│ b │ +└───┘ +``` + +### lag { #letsql.vendor.ibis.expr.types.generic.Column.lag } + +```python +lag(offset=None, default=None) +``` + +Return the row located at `offset` rows **before** the current row. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------|----------------------------------------------------------------------------------------------------------------------------|-----------------------------------------|-----------| +| offset | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) \| None | Index of row to select | `None` | +| default | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) \| None | Value used if no row exists at `offset` | `None` | + +### last { #letsql.vendor.ibis.expr.types.generic.Column.last } + +```python +last(where=None, order_by=None, include_null=False) +``` + +Return the last value of a column. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------------|------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | An optional filter expression. If provided, only rows where `where` is `True` will be included in the aggregate. | `None` | +| order_by | [Any](`typing.Any`) | An ordering key (or keys) to use to order the rows before aggregating. If not provided, the meaning of `last` is undefined and will be backend specific. | `None` | +| include_null | [bool](`bool`) | Whether to include null values when performing this aggregation. Set to `True` to include nulls in the result. | `False` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"chars": ["a", "b", "c", "d"]}) +>>> t +┏━━━━━━━━┓ +┃ chars ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ a │ +│ b │ +│ c │ +│ d │ +└────────┘ +>>> t.chars.last() +┌───┐ +│ d │ +└───┘ +>>> t.chars.last(where=t.chars != "d") +┌───┐ +│ c │ +└───┘ +``` + +### lead { #letsql.vendor.ibis.expr.types.generic.Column.lead } + +```python +lead(offset=None, default=None) +``` + +Return the row located at `offset` rows **after** the current row. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------|----------------------------------------------------------------------------------------------------------------------------|-----------------------------------------|-----------| +| offset | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) \| None | Index of row to select | `None` | +| default | [Value](`letsql.vendor.ibis.expr.types.generic.Value`) \| None | Value used if no row exists at `offset` | `None` | + +### max { #letsql.vendor.ibis.expr.types.generic.Column.max } + +```python +max(where=None) +``` + +Return the maximum of a column. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|-----------------------------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter in values when `where` is `True` | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|-----------------------------| +| | [Scalar](`letsql.vendor.ibis.expr.types.generic.Scalar`) | The maximum value in `self` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.max() +┌──────┐ +│ 6300 │ +└──────┘ +>>> t.body_mass_g.max(where=t.species == "Chinstrap") +┌──────┐ +│ 4800 │ +└──────┘ +``` + +### median { #letsql.vendor.ibis.expr.types.generic.Column.median } + +```python +median(where=None) +``` + +Return the median of the column. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Optional boolean expression. If given, only the values where `where` evaluates to true will be considered for the median. | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|----------------------| +| | [Scalar](`letsql.vendor.ibis.expr.types.generic.Scalar`) | Median of the column | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +``` + +Compute the median of `bill_depth_mm` + +```python +>>> t.bill_depth_mm.median() +┌──────┐ +│ 17.3 │ +└──────┘ +>>> t.group_by(t.species).agg(median_bill_depth=t.bill_depth_mm.median()).order_by( +... ibis.desc("median_bill_depth") +... ) +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓ +┃ species ┃ median_bill_depth ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼───────────────────┤ +│ Chinstrap │ 18.45 │ +│ Adelie │ 18.40 │ +│ Gentoo │ 15.00 │ +└───────────┴───────────────────┘ +``` + +In addition to numeric types, any orderable non-numeric types such as +strings and dates work with `median`. + +```python +>>> t.group_by(t.island).agg(median_species=t.species.median()).order_by( +... ibis.desc("median_species") +... ) +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┓ +┃ island ┃ median_species ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━┩ +│ string │ string │ +├───────────┼────────────────┤ +│ Biscoe │ Gentoo │ +│ Dream │ Chinstrap │ +│ Torgersen │ Adelie │ +└───────────┴────────────────┘ +``` + +### min { #letsql.vendor.ibis.expr.types.generic.Column.min } + +```python +min(where=None) +``` + +Return the minimum of a column. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|-----------------------------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter in values when `where` is `True` | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|-----------------------------| +| | [Scalar](`letsql.vendor.ibis.expr.types.generic.Scalar`) | The minimum value in `self` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.min() +┌──────┐ +│ 2700 │ +└──────┘ +>>> t.body_mass_g.min(where=t.species == "Adelie") +┌──────┐ +│ 2850 │ +└──────┘ +``` + +### nth { #letsql.vendor.ibis.expr.types.generic.Column.nth } + +```python +nth(n) +``` + +Return the `n`th value (0-indexed) over a window. + +`.nth(0)` is equivalent to `.first()`. Negative will result in `NULL`. +If the value of `n` is greater than the number of rows in the window, +`NULL` will be returned. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------------------------------------------------------------------|--------------------|------------| +| n | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) | Desired rank value | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|-----------------------------| +| | [Column](`letsql.vendor.ibis.expr.types.generic.Column`) | The nth value over a window | + +### nunique { #letsql.vendor.ibis.expr.types.generic.Column.nunique } + +```python +nunique(where=None) +``` + +Compute the number of distinct rows in an expression. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|-------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter expression | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|----------------------------------------------| +| | [IntegerScalar](`letsql.vendor.ibis.expr.types.numeric.IntegerScalar`) | Number of distinct elements in an expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.examples.penguins.fetch() +>>> t.body_mass_g.nunique() +┌────┐ +│ 94 │ +└────┘ +>>> t.body_mass_g.nunique(where=t.species == "Adelie") +┌────┐ +│ 55 │ +└────┘ +``` \ No newline at end of file diff --git a/docs/reference/expression-numeric.qmd b/docs/reference/expression-numeric.qmd new file mode 100644 index 00000000..e90775d9 --- /dev/null +++ b/docs/reference/expression-numeric.qmd @@ -0,0 +1,945 @@ +# Numeric and Boolean expressions + +Integer, floating point, decimal, and boolean expressions. + +# NumericColumn { #letsql.vendor.ibis.expr.types.numeric.NumericColumn } + +```python +NumericColumn(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [abs](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.abs) | Return the absolute value of `self`. | +| [acos](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.acos) | Compute the arc cosine of `self`. | +| [asin](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.asin) | Compute the arc sine of `self`. | +| [atan](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.atan) | Compute the arc tangent of `self`. | +| [atan2](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.atan2) | Compute the two-argument version of arc tangent. | +| [bucket](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.bucket) | Compute a discrete binning of a numeric array. | +| [ceil](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.ceil) | Return the ceiling of `self`. | +| [corr](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.corr) | Return the correlation of two numeric columns. | +| [cos](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.cos) | Compute the cosine of `self`. | +| [cot](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.cot) | Compute the cotangent of `self`. | +| [cov](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.cov) | Return the covariance of two numeric columns. | +| [degrees](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.degrees) | Compute the degrees of `self` radians. | +| [exp](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.exp) | Compute $e^\texttt{self}$. | +| [floor](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.floor) | Return the floor of an expression. | +| [ln](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.ln) | Compute $\ln\left(\texttt{self}\right)$. | +| [log](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.log) | Compute $\log_{\texttt{base}}\left(\texttt{self}\right)$. | +| [log10](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.log10) | Compute $\log_{10}\left(\texttt{self}\right)$. | +| [log2](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.log2) | Compute $\log_{2}\left(\texttt{self}\right)$. | +| [mean](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.mean) | Return the mean of a numeric column. | +| [negate](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.negate) | Negate a numeric expression. | +| [radians](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.radians) | Compute radians from `self` degrees. | +| [round](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.round) | Round values to an indicated number of decimal places. | +| [sign](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.sign) | Return the sign of the input. | +| [sin](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.sin) | Compute the sine of `self`. | +| [sqrt](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.sqrt) | Compute the square root of `self`. | +| [std](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.std) | Return the standard deviation of a numeric column. | +| [sum](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.sum) | Return the sum of a numeric column. | +| [tan](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.tan) | Compute the tangent of `self`. | +| [var](#letsql.vendor.ibis.expr.types.numeric.NumericColumn.var) | Return the variance of a numeric column. | + +### abs { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.abs } + +```python +abs() +``` + +Return the absolute value of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 2, -3, 4]}) +>>> t.values.abs() +┏━━━━━━━━━━━━━┓ +┃ Abs(values) ┃ +┡━━━━━━━━━━━━━┩ +│ int64 │ +├─────────────┤ +│ 1 │ +│ 2 │ +│ 3 │ +│ 4 │ +└─────────────┘ +``` + +### acos { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.acos } + +```python +acos() +``` + +Compute the arc cosine of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.acos() +┏━━━━━━━━━━━━━━┓ +┃ Acos(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ 3.141593 │ +│ 1.570796 │ +│ 0.000000 │ +└──────────────┘ +``` + +### asin { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.asin } + +```python +asin() +``` + +Compute the arc sine of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.asin() +┏━━━━━━━━━━━━━━┓ +┃ Asin(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ -1.570796 │ +│ 0.000000 │ +│ 1.570796 │ +└──────────────┘ +``` + +### atan { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.atan } + +```python +atan() +``` + +Compute the arc tangent of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.atan() +┏━━━━━━━━━━━━━━┓ +┃ Atan(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ -0.785398 │ +│ 0.000000 │ +│ 0.785398 │ +└──────────────┘ +``` + +### atan2 { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.atan2 } + +```python +atan2(other) +``` + +Compute the two-argument version of arc tangent. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.atan2(0) +┏━━━━━━━━━━━━━━━━━━┓ +┃ Atan2(values, 0) ┃ +┡━━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────────┤ +│ -1.570796 │ +│ 0.000000 │ +│ 1.570796 │ +└──────────────────┘ +``` + +### bucket { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.bucket } + +```python +bucket( + buckets, + closed='left', + close_extreme=True, + include_under=False, + include_over=False, +) +``` + +Compute a discrete binning of a numeric array. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------------|--------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------| +| buckets | [Sequence](`collections.abc.Sequence`)\[[int](`int`)\] | List of buckets | _required_ | +| closed | [Literal](`typing.Literal`)\[\'left\', \'right\'\] | Which side of each interval is closed. For example: ```python buckets = [0, 100, 200] closed = "left" # 100 falls in 2nd bucket closed = "right" # 100 falls in 1st bucket ``` | `'left'` | +| close_extreme | [bool](`bool`) | Whether the extreme values fall in the last bucket | `True` | +| include_over | [bool](`bool`) | Include values greater than the last bucket in the last bucket | `False` | +| include_under | [bool](`bool`) | Include values less than the first bucket in the first bucket | `False` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|---------------------------------| +| | [IntegerColumn](`letsql.vendor.ibis.expr.types.numeric.IntegerColumn`) | A categorical column expression | + +### ceil { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.ceil } + +```python +ceil() +``` + +Return the ceiling of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 1.1, 2, 2.1, 3.3]}) +>>> t.values.ceil() +┏━━━━━━━━━━━━━━┓ +┃ Ceil(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ int64 │ +├──────────────┤ +│ 1 │ +│ 2 │ +│ 2 │ +│ 3 │ +│ 4 │ +└──────────────┘ +``` + +### corr { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.corr } + +```python +corr(right, where=None, how='sample') +``` + +Return the correlation of two numeric columns. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|----------------------------------|------------| +| right | [NumericColumn](`letsql.vendor.ibis.expr.types.numeric.NumericColumn`) | Numeric column | _required_ | +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter | `None` | +| how | [Literal](`typing.Literal`)\[\'sample\', \'pop\'\] | Population or sample correlation | `'sample'` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|---------------------------------------| +| | [NumericScalar](`letsql.vendor.ibis.expr.types.numeric.NumericScalar`) | The correlation of `left` and `right` | + +### cos { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.cos } + +```python +cos() +``` + +Compute the cosine of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.cos() +┏━━━━━━━━━━━━━┓ +┃ Cos(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ 0.540302 │ +│ 1.000000 │ +│ 0.540302 │ +└─────────────┘ +``` + +### cot { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.cot } + +```python +cot() +``` + +Compute the cotangent of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, -2, 3]}) +>>> t.values.cot() +┏━━━━━━━━━━━━━┓ +┃ Cot(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ -0.642093 │ +│ 0.457658 │ +│ -7.015253 │ +└─────────────┘ +``` + +### cov { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.cov } + +```python +cov(right, where=None, how='sample') +``` + +Return the covariance of two numeric columns. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|---------------------------------|------------| +| right | [NumericColumn](`letsql.vendor.ibis.expr.types.numeric.NumericColumn`) | Numeric column | _required_ | +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter | `None` | +| how | [Literal](`typing.Literal`)\[\'sample\', \'pop\'\] | Population or sample covariance | `'sample'` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|--------------------------------------| +| | [NumericScalar](`letsql.vendor.ibis.expr.types.numeric.NumericScalar`) | The covariance of `self` and `right` | + +### degrees { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.degrees } + +```python +degrees() +``` + +Compute the degrees of `self` radians. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> from math import pi +>>> t = ibis.memtable({"values": [0, pi / 2, pi, 3 * pi / 2, 2 * pi]}) +>>> t.values.degrees() +┏━━━━━━━━━━━━━━━━━┓ +┃ Degrees(values) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────────┤ +│ 0.0 │ +│ 90.0 │ +│ 180.0 │ +│ 270.0 │ +│ 360.0 │ +└─────────────────┘ +``` + +### exp { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.exp } + +```python +exp() +``` + +Compute $e^\texttt{self}$. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|-------------------| +| | [NumericValue](`letsql.vendor.ibis.expr.types.numeric.NumericValue`) | $e^\texttt{self}$ | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": range(4)}) +>>> t.values.exp() +┏━━━━━━━━━━━━━┓ +┃ Exp(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ 1.000000 │ +│ 2.718282 │ +│ 7.389056 │ +│ 20.085537 │ +└─────────────┘ +``` + +### floor { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.floor } + +```python +floor() +``` + +Return the floor of an expression. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 1.1, 2, 2.1, 3.3]}) +>>> t.values.floor() +┏━━━━━━━━━━━━━━━┓ +┃ Floor(values) ┃ +┡━━━━━━━━━━━━━━━┩ +│ int64 │ +├───────────────┤ +│ 1 │ +│ 1 │ +│ 2 │ +│ 2 │ +│ 3 │ +└───────────────┘ +``` + +### ln { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.ln } + +```python +ln() +``` + +Compute $\ln\left(\texttt{self}\right)$. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 2.718281828, 3]}) +>>> t.values.ln() +┏━━━━━━━━━━━━┓ +┃ Ln(values) ┃ +┡━━━━━━━━━━━━┩ +│ float64 │ +├────────────┤ +│ 0.000000 │ +│ 1.000000 │ +│ 1.098612 │ +└────────────┘ +``` + +### log { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.log } + +```python +log(base=None) +``` + +Compute $\log_{\texttt{base}}\left(\texttt{self}\right)$. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------|---------------------------------------------------------|-----------| +| base | [NumericValue](`letsql.vendor.ibis.expr.types.numeric.NumericValue`) \| None | The base of the logarithm. If `None`, base `e` is used. | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|-------------------------------------| +| | [NumericValue](`letsql.vendor.ibis.expr.types.numeric.NumericValue`) | Logarithm of `arg` with base `base` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> from math import e +>>> t = ibis.memtable({"values": [e, e**2, e**3]}) +>>> t.values.log() +┏━━━━━━━━━━━━━┓ +┃ Log(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ 1.0 │ +│ 2.0 │ +│ 3.0 │ +└─────────────┘ +``` + + + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [10, 100, 1000]}) +>>> t.values.log(base=10) +┏━━━━━━━━━━━━━━━━━┓ +┃ Log(values, 10) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────────┤ +│ 1.0 │ +│ 2.0 │ +│ 3.0 │ +└─────────────────┘ +``` + +### log10 { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.log10 } + +```python +log10() +``` + +Compute $\log_{10}\left(\texttt{self}\right)$. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 10, 100]}) +>>> t.values.log10() +┏━━━━━━━━━━━━━━━┓ +┃ Log10(values) ┃ +┡━━━━━━━━━━━━━━━┩ +│ float64 │ +├───────────────┤ +│ 0.0 │ +│ 1.0 │ +│ 2.0 │ +└───────────────┘ +``` + +### log2 { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.log2 } + +```python +log2() +``` + +Compute $\log_{2}\left(\texttt{self}\right)$. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 2, 4, 8]}) +>>> t.values.log2() +┏━━━━━━━━━━━━━━┓ +┃ Log2(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ 0.0 │ +│ 1.0 │ +│ 2.0 │ +│ 3.0 │ +└──────────────┘ +``` + +### mean { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.mean } + +```python +mean(where=None) +``` + +Return the mean of a numeric column. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|---------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|----------------------------------| +| | [NumericScalar](`letsql.vendor.ibis.expr.types.numeric.NumericScalar`) | The mean of the input expression | + +### negate { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.negate } + +```python +negate() +``` + +Negate a numeric expression. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|----------------------------| +| | [NumericValue](`letsql.vendor.ibis.expr.types.numeric.NumericValue`) | A numeric value expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.negate() +┏━━━━━━━━━━━━━━━━┓ +┃ Negate(values) ┃ +┡━━━━━━━━━━━━━━━━┩ +│ int64 │ +├────────────────┤ +│ 1 │ +│ 0 │ +│ -1 │ +└────────────────┘ +``` + +### radians { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.radians } + +```python +radians() +``` + +Compute radians from `self` degrees. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [0, 90, 180, 270, 360]}) +>>> t.values.radians() +┏━━━━━━━━━━━━━━━━━┓ +┃ Radians(values) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────────┤ +│ 0.000000 │ +│ 1.570796 │ +│ 3.141593 │ +│ 4.712389 │ +│ 6.283185 │ +└─────────────────┘ +``` + +### round { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.round } + +```python +round(digits=None) +``` + +Round values to an indicated number of decimal places. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|----------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------| +| digits | [int](`int`) \| [IntegerValue](`letsql.vendor.ibis.expr.types.numeric.IntegerValue`) \| None | The number of digits to round to. Here's how the `digits` parameter affects the expression output type: - `digits` is `False`-y; `self.type()` is `decimal` → `decimal` - `digits` is nonzero; `self.type()` is `decimal` → `decimal` - `digits` is `False`-y; `self.type()` is Floating → `int64` - `digits` is nonzero; `self.type()` is Floating → `float64` | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|------------------------| +| | [NumericValue](`letsql.vendor.ibis.expr.types.numeric.NumericValue`) | The rounded expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1.22, 1.64, 2.15, 2.54]}) +>>> t +┏━━━━━━━━━┓ +┃ values ┃ +┡━━━━━━━━━┩ +│ float64 │ +├─────────┤ +│ 1.22 │ +│ 1.64 │ +│ 2.15 │ +│ 2.54 │ +└─────────┘ +>>> t.values.round() +┏━━━━━━━━━━━━━━━┓ +┃ Round(values) ┃ +┡━━━━━━━━━━━━━━━┩ +│ int64 │ +├───────────────┤ +│ 1 │ +│ 2 │ +│ 2 │ +│ 3 │ +└───────────────┘ +>>> t.values.round(digits=1) +┏━━━━━━━━━━━━━━━━━━┓ +┃ Round(values, 1) ┃ +┡━━━━━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────────┤ +│ 1.2 │ +│ 1.6 │ +│ 2.2 │ +│ 2.5 │ +└──────────────────┘ +``` + +### sign { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.sign } + +```python +sign() +``` + +Return the sign of the input. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 2, -3, 4]}) +>>> t.values.sign() +┏━━━━━━━━━━━━━━┓ +┃ Sign(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ int64 │ +├──────────────┤ +│ -1 │ +│ 1 │ +│ -1 │ +│ 1 │ +└──────────────┘ +``` + +### sin { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.sin } + +```python +sin() +``` + +Compute the sine of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.sin() +┏━━━━━━━━━━━━━┓ +┃ Sin(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ -0.841471 │ +│ 0.000000 │ +│ 0.841471 │ +└─────────────┘ +``` + +### sqrt { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.sqrt } + +```python +sqrt() +``` + +Compute the square root of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [1, 4, 9, 16]}) +>>> t.values.sqrt() +┏━━━━━━━━━━━━━━┓ +┃ Sqrt(values) ┃ +┡━━━━━━━━━━━━━━┩ +│ float64 │ +├──────────────┤ +│ 1.0 │ +│ 2.0 │ +│ 3.0 │ +│ 4.0 │ +└──────────────┘ +``` + +### std { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.std } + +```python +std(where=None, how='sample') +``` + +Return the standard deviation of a numeric column. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|-----------------------------------------|------------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter | `None` | +| how | [Literal](`typing.Literal`)\[\'sample\', \'pop\'\] | Sample or population standard deviation | `'sample'` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|-----------------------------| +| | [NumericScalar](`letsql.vendor.ibis.expr.types.numeric.NumericScalar`) | Standard deviation of `arg` | + +### sum { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.sum } + +```python +sum(where=None) +``` + +Return the sum of a numeric column. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|---------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|---------------------------------| +| | [NumericScalar](`letsql.vendor.ibis.expr.types.numeric.NumericScalar`) | The sum of the input expression | + +### tan { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.tan } + +```python +tan() +``` + +Compute the tangent of `self`. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"values": [-1, 0, 1]}) +>>> t.values.tan() +┏━━━━━━━━━━━━━┓ +┃ Tan(values) ┃ +┡━━━━━━━━━━━━━┩ +│ float64 │ +├─────────────┤ +│ -1.557408 │ +│ 0.000000 │ +│ 1.557408 │ +└─────────────┘ +``` + +### var { #letsql.vendor.ibis.expr.types.numeric.NumericColumn.var } + +```python +var(where=None, how='sample') +``` + +Return the variance of a numeric column. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|-------------------------------|------------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Filter | `None` | +| how | [Literal](`typing.Literal`)\[\'sample\', \'pop\'\] | Sample or population variance | `'sample'` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|-----------------------------| +| | [NumericScalar](`letsql.vendor.ibis.expr.types.numeric.NumericScalar`) | Standard deviation of `arg` | + +# IntegerColumn { #letsql.vendor.ibis.expr.types.numeric.IntegerColumn } + +```python +IntegerColumn(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [bit_and](#letsql.vendor.ibis.expr.types.numeric.IntegerColumn.bit_and) | Aggregate the column using the bitwise and operator. | +| [bit_or](#letsql.vendor.ibis.expr.types.numeric.IntegerColumn.bit_or) | Aggregate the column using the bitwise or operator. | +| [bit_xor](#letsql.vendor.ibis.expr.types.numeric.IntegerColumn.bit_xor) | Aggregate the column using the bitwise exclusive or operator. | +| [to_timestamp](#letsql.vendor.ibis.expr.types.numeric.IntegerColumn.to_timestamp) | | + +### bit_and { #letsql.vendor.ibis.expr.types.numeric.IntegerColumn.bit_and } + +```python +bit_and(where=None) +``` + +Aggregate the column using the bitwise and operator. + +### bit_or { #letsql.vendor.ibis.expr.types.numeric.IntegerColumn.bit_or } + +```python +bit_or(where=None) +``` + +Aggregate the column using the bitwise or operator. + +### bit_xor { #letsql.vendor.ibis.expr.types.numeric.IntegerColumn.bit_xor } + +```python +bit_xor(where=None) +``` + +Aggregate the column using the bitwise exclusive or operator. + +### to_timestamp { #letsql.vendor.ibis.expr.types.numeric.IntegerColumn.to_timestamp } + +```python +to_timestamp(unit='s') +``` + + + +# FloatingColumn { #letsql.vendor.ibis.expr.types.numeric.FloatingColumn } + +```python +FloatingColumn(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [isinf](#letsql.vendor.ibis.expr.types.numeric.FloatingColumn.isinf) | Return whether the value is infinity. | +| [isnan](#letsql.vendor.ibis.expr.types.numeric.FloatingColumn.isnan) | Return whether the value is NaN. | + +### isinf { #letsql.vendor.ibis.expr.types.numeric.FloatingColumn.isinf } + +```python +isinf() +``` + +Return whether the value is infinity. + +### isnan { #letsql.vendor.ibis.expr.types.numeric.FloatingColumn.isnan } + +```python +isnan() +``` + +Return whether the value is NaN. \ No newline at end of file diff --git a/docs/reference/expression-relations.qmd b/docs/reference/expression-relations.qmd new file mode 100644 index 00000000..3cedec1c --- /dev/null +++ b/docs/reference/expression-relations.qmd @@ -0,0 +1,1406 @@ +# Table expressions + +Tables are one of the core data structures in Ibis. + +# Table { #letsql.vendor.ibis.expr.types.relations.Table } + +```python +Table(self, arg) +``` + +An immutable and lazy dataframe. + +Analogous to a SQL table or a pandas DataFrame. A table expression contains +an [ordered set of named columns](./schemas.qmd#ibis.expr.schema.Schema), +each with a single known type. Unless explicitly ordered with an +[`.order_by()`](./expression-tables.qmd#letsql.expr.types.relations.Table.order_by), +the order of rows is undefined. + +Table immutability means that the data underlying an Ibis `Table` cannot be modified: every +method on a Table returns a new Table with those changes. Laziness +means that an Ibis `Table` expression does not run your computation every time you call one of its methods. +Instead, it is a symbolic expression that represents a set of operations +to be performed, which typically is translated into a SQL query. That +SQL query is then executed on a backend, where the data actually lives. +The result (now small enough to be manageable) can then be materialized back +into python as a pandas/pyarrow/python DataFrame/Column/scalar. + +You will not create Table objects directly. Instead, you will create one + +- from a pandas DataFrame, pyarrow table, Polars table, or raw python dicts/lists + with [`letsql.memtable(df)`](./expression-tables.qmd#letsql.memtable) +- from an existing table in a data platform with + [`connection.table("name")`](./expression-tables.qmd#letsql.backends.duckdb.Backend.table) +- from a file or URL, into a specific backend with + [`connection.read_csv/parquet/json("path/to/file")`](../backends/duckdb.qmd#letsql.backends.duckdb.Backend.read_csv) + (only some backends, typically local ones, support this) +- from a file or URL, into the default backend with + [`ibis.read_csv/read_json/read_parquet("path/to/file")`](./expression-tables.qmd#ibis.read_csv) + +## Methods + +| Name | Description | +| --- | --- | +| [alias](#letsql.vendor.ibis.expr.types.relations.Table.alias) | Create a table expression with a specific name `alias`. | +| [as_scalar](#letsql.vendor.ibis.expr.types.relations.Table.as_scalar) | Inform ibis that the table expression should be treated as a scalar. | +| [count](#letsql.vendor.ibis.expr.types.relations.Table.count) | Compute the number of rows in the table. | +| [difference](#letsql.vendor.ibis.expr.types.relations.Table.difference) | Compute the set difference of multiple table expressions. | +| [distinct](#letsql.vendor.ibis.expr.types.relations.Table.distinct) | Return a Table with duplicate rows removed. | +| [dropna](#letsql.vendor.ibis.expr.types.relations.Table.dropna) | Deprecated - use `drop_null` instead. | +| [fillna](#letsql.vendor.ibis.expr.types.relations.Table.fillna) | Deprecated - use `fill_null` instead. | +| [filter](#letsql.vendor.ibis.expr.types.relations.Table.filter) | Select rows from `table` based on `predicates`. | +| [intersect](#letsql.vendor.ibis.expr.types.relations.Table.intersect) | Compute the set intersection of multiple table expressions. | +| [limit](#letsql.vendor.ibis.expr.types.relations.Table.limit) | Select `n` rows from `self` starting at `offset`. | +| [order_by](#letsql.vendor.ibis.expr.types.relations.Table.order_by) | Sort a table by one or more expressions. | +| [sample](#letsql.vendor.ibis.expr.types.relations.Table.sample) | Sample a fraction of rows from a table. | +| [select](#letsql.vendor.ibis.expr.types.relations.Table.select) | Compute a new table expression using `exprs` and `named_exprs`. | +| [sql](#letsql.vendor.ibis.expr.types.relations.Table.sql) | Run a SQL query against a table expression. | +| [union](#letsql.vendor.ibis.expr.types.relations.Table.union) | Compute the set union of multiple table expressions. | +| [view](#letsql.vendor.ibis.expr.types.relations.Table.view) | Create a new table expression distinct from the current one. | +| [cache](#letsql.vendor.ibis.expr.types.relations.Table.cache) | Cache the results of a computation to improve performance on subsequent executions. | +| [into_backend](#letsql.vendor.ibis.expr.types.relations.Table.into_backend) | Converts the Expr to a table in the given backend `con` with an optional table name `name`. | + +### alias { #letsql.vendor.ibis.expr.types.relations.Table.alias } + +```python +alias(alias) +``` + +Create a table expression with a specific name `alias`. + +This method is useful for exposing an ibis expression to the underlying +backend for use in the +[`Table.sql`](#ibis.expr.types.relations.Table.sql) method. + +::: {.callout-note} +## `.alias` will create a temporary view + +`.alias` creates a temporary view in the database. + +This side effect will be removed in a future version of ibis and **is +not part of the public API**. +::: + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------|------------------------------|------------| +| alias | [str](`str`) | Name of the child expression | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|---------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | An table expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch() +>>> expr = t.alias("pingüinos").sql('SELECT * FROM "pingüinos" LIMIT 5') +>>> expr +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ float64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186.0 │ … │ +│ Adelie │ Torgersen │ 40.3 │ 18.0 │ 195.0 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Torgersen │ 36.7 │ 19.3 │ 193.0 │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +``` + +### as_scalar { #letsql.vendor.ibis.expr.types.relations.Table.as_scalar } + +```python +as_scalar() +``` + +Inform ibis that the table expression should be treated as a scalar. + +Note that the table must have exactly one column and one row for this to +work. If the table has more than one column an error will be raised in +expression construction time. If the table has more than one row an +error will be raised by the backend when the expression is executed. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|-------------------------------------------------------|-------------------| +| | [Scalar](`letsql.vendor.ibis.expr.types.uuid.Scalar`) | A scalar subquery | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch() +>>> heavy_gentoo = t.filter(t.species == "Gentoo", t.body_mass_g > 6200) +>>> from_that_island = t.filter(t.island == heavy_gentoo.select("island").as_scalar()) +>>> from_that_island.species.value_counts().order_by("species") +┏━━━━━━━━━┳━━━━━━━━━━━━━━━┓ +┃ species ┃ species_count ┃ +┡━━━━━━━━━╇━━━━━━━━━━━━━━━┩ +│ string │ int64 │ +├─────────┼───────────────┤ +│ Adelie │ 44 │ +│ Gentoo │ 124 │ +└─────────┴───────────────┘ +``` + +### count { #letsql.vendor.ibis.expr.types.relations.Table.count } + +```python +count(where=None) +``` + +Compute the number of rows in the table. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------|-----------| +| where | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| None | Optional boolean expression to filter rows when counting. | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------------|-----------------------------| +| | [IntegerScalar](`letsql.vendor.ibis.expr.types.numeric.IntegerScalar`) | Number of rows in the table | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.memtable({"a": ["foo", "bar", "baz"]}) +>>> t +┏━━━━━━━━┓ +┃ a ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ foo │ +│ bar │ +│ baz │ +└────────┘ +>>> t.count() +┌───┐ +│ 3 │ +└───┘ +>>> t.count(t.a != "foo") +┌───┐ +│ 2 │ +└───┘ +>>> type(t.count()) + +``` + +### difference { #letsql.vendor.ibis.expr.types.relations.Table.difference } + +```python +difference(table, *rest, distinct=True) +``` + +Compute the set difference of multiple table expressions. + +The input tables must have identical schemas. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|----------------------------------------------------------|------------------------------------------------------------|------------| +| table | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | A table expression | _required_ | +| *rest | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | Additional table expressions | `()` | +| distinct | [bool](`bool`) | Only diff distinct rows not occurring in the calling table | `True` | + +#### See Also {.doc-section .doc-section-see-also} + +[`ibis.difference`](./expression-tables.qmd#ibis.difference) + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|--------------------------------------------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | The rows present in `self` that are not present in `tables`. | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t1 = ls.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = ls.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> t1.difference(t2) +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +└───────┘ +``` + +### distinct { #letsql.vendor.ibis.expr.types.relations.Table.distinct } + +```python +distinct(on=None, keep='first') +``` + +Return a Table with duplicate rows removed. + +Similar to `pandas.DataFrame.drop_duplicates()`. + +::: {.callout-note} +## Some backends do not support `keep='last'` +::: + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------| +| on | [str](`str`) \| [Iterable](`collections.abc.Iterable`)\[[str](`str`)\] \| [s](`letsql.vendor.ibis.selectors`).[Selector](`letsql.vendor.ibis.selectors.Selector`) \| None | Only consider certain columns for identifying duplicates. By default, deduplicate all of the columns. | `None` | +| keep | [Literal](`typing.Literal`)\[\'first\', \'last\'\] \| None | Determines which duplicates to keep. - `"first"`: Drop duplicates except for the first occurrence. - `"last"`: Drop duplicates except for the last occurrence. - `None`: Drop all duplicates | `'first'` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> import letsql.examples as ex +>>> import letsql.selectors as s +>>> ls.options.interactive = True +>>> t = ex.penguins.fetch() +>>> t +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ float64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186.0 │ … │ +│ Adelie │ Torgersen │ 40.3 │ 18.0 │ 195.0 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Torgersen │ 36.7 │ 19.3 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 39.3 │ 20.6 │ 190.0 │ … │ +│ Adelie │ Torgersen │ 38.9 │ 17.8 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.2 │ 19.6 │ 195.0 │ … │ +│ Adelie │ Torgersen │ 34.1 │ 18.1 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 42.0 │ 20.2 │ 190.0 │ … │ +│ … │ … │ … │ … │ … │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +``` + +Compute the distinct rows of a subset of columns + +```python +>>> t[["species", "island"]].distinct().order_by(s.all()) +┏━━━━━━━━━━━┳━━━━━━━━━━━┓ +┃ species ┃ island ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━┩ +│ string │ string │ +├───────────┼───────────┤ +│ Adelie │ Biscoe │ +│ Adelie │ Dream │ +│ Adelie │ Torgersen │ +│ Chinstrap │ Dream │ +│ Gentoo │ Biscoe │ +└───────────┴───────────┘ +``` + +Drop all duplicate rows except the first + +```python +>>> t.distinct(on=["species", "island"], keep="first").order_by(s.all()) +┏━━━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_… ┃ flipper_length_mm ┃ ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━┩ +│ string │ string │ float64 │ float64 │ float64 │ │ +├───────────┼───────────┼────────────────┼──────────────┼───────────────────┼──┤ +│ Adelie │ Biscoe │ 37.8 │ 18.3 │ 174.0 │ │ +│ Adelie │ Dream │ 39.5 │ 16.7 │ 178.0 │ │ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ │ +│ Chinstrap │ Dream │ 46.5 │ 17.9 │ 192.0 │ │ +│ Gentoo │ Biscoe │ 46.1 │ 13.2 │ 211.0 │ │ +└───────────┴───────────┴────────────────┴──────────────┴───────────────────┴──┘ +``` + +Drop all duplicate rows except the last + +```python +>>> t.distinct(on=["species", "island"], keep="last").order_by(s.all()) +┏━━━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_… ┃ flipper_length_mm ┃ ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━┩ +│ string │ string │ float64 │ float64 │ float64 │ │ +├───────────┼───────────┼────────────────┼──────────────┼───────────────────┼──┤ +│ Adelie │ Biscoe │ 42.7 │ 18.3 │ 196.0 │ │ +│ Adelie │ Dream │ 41.5 │ 18.5 │ 201.0 │ │ +│ Adelie │ Torgersen │ 43.1 │ 19.2 │ 197.0 │ │ +│ Chinstrap │ Dream │ 50.2 │ 18.7 │ 198.0 │ │ +│ Gentoo │ Biscoe │ 49.9 │ 16.1 │ 213.0 │ │ +└───────────┴───────────┴────────────────┴──────────────┴───────────────────┴──┘ +``` + +Drop all duplicated rows + +```python +>>> expr = t.distinct(on=["species", "island", "year", "bill_length_mm"], keep=None) +>>> expr.count() +┌─────┐ +│ 273 │ +└─────┘ +>>> t.count() +┌─────┐ +│ 344 │ +└─────┘ +``` + +You can pass [`selectors`](./selectors.qmd) to `on` + +```python +>>> t.distinct(on=~s.numeric()) +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ int64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Biscoe │ 37.8 │ 18.3 │ 174 │ … │ +│ Adelie │ Biscoe │ 37.7 │ 18.7 │ 180 │ … │ +│ Adelie │ Dream │ 39.5 │ 16.7 │ 178 │ … │ +│ Adelie │ Dream │ 37.2 │ 18.1 │ 178 │ … │ +│ Adelie │ Dream │ 37.5 │ 18.9 │ 179 │ … │ +│ Gentoo │ Biscoe │ 46.1 │ 13.2 │ 211 │ … │ +│ Gentoo │ Biscoe │ 50.0 │ 16.3 │ 230 │ … │ +│ … │ … │ … │ … │ … │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +``` + +The only valid values of `keep` are `"first"`, `"last"` and [](`None`). + +```python +>>> t.distinct(on="species", keep="second") # quartodoc: +EXPECTED_FAILURE +Traceback (most recent call last): + ... +letsql.vendor.ibis.common.exceptions.LetSQLError: Invalid value for `keep`: 'second', must be 'first', 'last' or None +``` + +### dropna { #letsql.vendor.ibis.expr.types.relations.Table.dropna } + +```python +dropna(subset=None, how='any') +``` + +Deprecated - use `drop_null` instead. + +### fillna { #letsql.vendor.ibis.expr.types.relations.Table.fillna } + +```python +fillna(replacements) +``` + +Deprecated - use `fill_null` instead. + +### filter { #letsql.vendor.ibis.expr.types.relations.Table.filter } + +```python +filter(*predicates) +``` + +Select rows from `table` based on `predicates`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------|-----------| +| predicates | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) \| [Sequence](`collections.abc.Sequence`)\[[ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`)\] \| [IfAnyAll](`letsql.vendor.ibis.selectors.IfAnyAll`) | Boolean value expressions used to select rows in `table`. | `()` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|---------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | Filtered table expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch() +>>> t +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ float64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186.0 │ … │ +│ Adelie │ Torgersen │ 40.3 │ 18.0 │ 195.0 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Torgersen │ 36.7 │ 19.3 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 39.3 │ 20.6 │ 190.0 │ … │ +│ Adelie │ Torgersen │ 38.9 │ 17.8 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.2 │ 19.6 │ 195.0 │ … │ +│ Adelie │ Torgersen │ 34.1 │ 18.1 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 42.0 │ 20.2 │ 190.0 │ … │ +│ … │ … │ … │ … │ … │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +>>> t.filter([t.species == "Adelie", t.body_mass_g > 3500]).sex.value_counts().drop_null( +... "sex" +... ).order_by("sex") +┏━━━━━━━━┳━━━━━━━━━━━┓ +┃ sex ┃ sex_count ┃ +┡━━━━━━━━╇━━━━━━━━━━━┩ +│ string │ int64 │ +├────────┼───────────┤ +│ female │ 22 │ +│ male │ 68 │ +└────────┴───────────┘ +``` + +### intersect { #letsql.vendor.ibis.expr.types.relations.Table.intersect } + +```python +intersect(table, *rest, distinct=True) +``` + +Compute the set intersection of multiple table expressions. + +The input tables must have identical schemas. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|----------------------------------------------------------|------------------------------|------------| +| table | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | A table expression | _required_ | +| *rest | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | Additional table expressions | `()` | +| distinct | [bool](`bool`) | Only return distinct rows | `True` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|--------------------------------------------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | A new table containing the intersection of all input tables. | + +#### See Also {.doc-section .doc-section-see-also} + +[`ibis.intersect`](./expression-tables.qmd#ibis.intersect) + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t1 = ls.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = ls.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> t1.intersect(t2) +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +└───────┘ +``` + +### limit { #letsql.vendor.ibis.expr.types.relations.Table.limit } + +```python +limit(n, offset=0) +``` + +Select `n` rows from `self` starting at `offset`. + +::: {.callout-note} +## The result set is not deterministic without a call to [`order_by`](#ibis.expr.types.relations.Table.order_by). +::: + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|----------------------|--------------------------------------------------------------------------------------------|------------| +| n | [int](`int`) \| None | Number of rows to include. If `None`, the entire table is selected starting from `offset`. | _required_ | +| offset | [int](`int`) | Number of rows to skip first | `0` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|---------------------------------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | The first `n` rows of `self` starting at `offset` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.memtable({"a": [1, 1, 2], "b": ["c", "a", "a"]}) +>>> t +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ c │ +│ 1 │ a │ +│ 2 │ a │ +└───────┴────────┘ +>>> t.limit(2) +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ c │ +│ 1 │ a │ +└───────┴────────┘ +``` + +You can use `None` with `offset` to slice starting from a particular row + +```python +>>> t.limit(None, offset=1) +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ a │ +│ 2 │ a │ +└───────┴────────┘ +``` + +#### See Also {.doc-section .doc-section-see-also} + +[`Table.order_by`](#ibis.expr.types.relations.Table.order_by) + +### order_by { #letsql.vendor.ibis.expr.types.relations.Table.order_by } + +```python +order_by(*by) +``` + +Sort a table by one or more expressions. + +Similar to `pandas.DataFrame.sort_values()`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------|-----------| +| by | [str](`str`) \| [ir](`letsql.vendor.ibis.expr.types`).[Column](`letsql.vendor.ibis.expr.types.Column`) \| [s](`letsql.vendor.ibis.selectors`).[Selector](`letsql.vendor.ibis.selectors.Selector`) \| [Sequence](`collections.abc.Sequence`)\[[str](`str`)\] \| [Sequence](`collections.abc.Sequence`)\[[ir](`letsql.vendor.ibis.expr.types`).[Column](`letsql.vendor.ibis.expr.types.Column`)\] \| [Sequence](`collections.abc.Sequence`)\[[s](`letsql.vendor.ibis.selectors`).[Selector](`letsql.vendor.ibis.selectors.Selector`)\] \| None | Expressions to sort the table by. | `()` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|---------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | Sorted table | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.memtable( +... { +... "a": [3, 2, 1, 3], +... "b": ["a", "B", "c", "D"], +... "c": [4, 6, 5, 7], +... } +... ) +>>> t +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 3 │ a │ 4 │ +│ 2 │ B │ 6 │ +│ 1 │ c │ 5 │ +│ 3 │ D │ 7 │ +└───────┴────────┴───────┘ +``` + +Sort by b. Default is ascending. Note how capital letters come before lowercase + +```python +>>> t.order_by("b") +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 2 │ B │ 6 │ +│ 3 │ D │ 7 │ +│ 3 │ a │ 4 │ +│ 1 │ c │ 5 │ +└───────┴────────┴───────┘ +``` + +Sort in descending order + +```python +>>> t.order_by(ls.desc("b")) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 1 │ c │ 5 │ +│ 3 │ a │ 4 │ +│ 3 │ D │ 7 │ +│ 2 │ B │ 6 │ +└───────┴────────┴───────┘ +``` + +You can also use the deferred API to get the same result + +```python +>>> from letsql import _ +>>> t.order_by(_.b.desc()) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 1 │ c │ 5 │ +│ 3 │ a │ 4 │ +│ 3 │ D │ 7 │ +│ 2 │ B │ 6 │ +└───────┴────────┴───────┘ +``` + +Sort by multiple columns/expressions + +```python +>>> t.order_by(["a", _.c.desc()]) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 1 │ c │ 5 │ +│ 2 │ B │ 6 │ +│ 3 │ D │ 7 │ +│ 3 │ a │ 4 │ +└───────┴────────┴───────┘ +``` + +You can actually pass arbitrary expressions to use as sort keys. +For example, to ignore the case of the strings in column `b` + +```python +>>> t.order_by(_.b.lower()) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 3 │ a │ 4 │ +│ 2 │ B │ 6 │ +│ 1 │ c │ 5 │ +│ 3 │ D │ 7 │ +└───────┴────────┴───────┘ +``` + +This means that shuffling a Table is super simple + +```python +>>> t.order_by(ls.random()) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┓ +┃ a ┃ b ┃ c ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼────────┼───────┤ +│ 1 │ c │ 5 │ +│ 3 │ D │ 7 │ +│ 3 │ a │ 4 │ +│ 2 │ B │ 6 │ +└───────┴────────┴───────┘ +``` + +[Selectors](./selectors.qmd) are allowed as sort keys and are a concise way to sort by +multiple columns matching some criteria + +```python +>>> import letsql.selectors as s +>>> penguins = ls.examples.penguins.fetch() +>>> penguins[["year", "island"]].value_counts().order_by(s.startswith("year")) +┏━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓ +┃ year ┃ island ┃ year_island_count ┃ +┡━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼───────────┼───────────────────┤ +│ 2007 │ Torgersen │ 20 │ +│ 2007 │ Biscoe │ 44 │ +│ 2007 │ Dream │ 46 │ +│ 2008 │ Torgersen │ 16 │ +│ 2008 │ Dream │ 34 │ +│ 2008 │ Biscoe │ 64 │ +│ 2009 │ Torgersen │ 16 │ +│ 2009 │ Dream │ 44 │ +│ 2009 │ Biscoe │ 60 │ +└───────┴───────────┴───────────────────┘ +``` + +Use the [`across`](./selectors.qmd#ibis.selectors.across) selector to +apply a specific order to multiple columns + +```python +>>> penguins[["year", "island"]].value_counts().order_by( +... s.across(s.startswith("year"), _.desc()) +... ) +┏━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓ +┃ year ┃ island ┃ year_island_count ┃ +┡━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ string │ int64 │ +├───────┼───────────┼───────────────────┤ +│ 2009 │ Biscoe │ 60 │ +│ 2009 │ Dream │ 44 │ +│ 2009 │ Torgersen │ 16 │ +│ 2008 │ Biscoe │ 64 │ +│ 2008 │ Dream │ 34 │ +│ 2008 │ Torgersen │ 16 │ +│ 2007 │ Dream │ 46 │ +│ 2007 │ Biscoe │ 44 │ +│ 2007 │ Torgersen │ 20 │ +└───────┴───────────┴───────────────────┘ +``` + +### sample { #letsql.vendor.ibis.expr.types.relations.Table.sample } + +```python +sample(fraction, *, method='row', seed=None) +``` + +Sample a fraction of rows from a table. + +::: {.callout-note} +## Results may be non-repeatable + +Sampling is by definition a random operation. Some backends support +specifying a `seed` for repeatable results, but not all backends +support that option. And some backends (duckdb, for example) do support +specifying a seed but may still not have repeatable results in all +cases. + +In all cases, results are backend-specific. An execution against one +backend is unlikely to sample the same rows when executed against a +different backend, even with the same `seed` set. +::: + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|---------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------| +| fraction | [float](`float`) | The percentage of rows to include in the sample, expressed as a float between 0 and 1. | _required_ | +| method | [Literal](`typing.Literal`)\[\'row\', \'block\'\] | The sampling method to use. The default is "row", which includes each row with a probability of `fraction`. If method is "block", some backends may instead perform sampling a fraction of blocks of rows (where "block" is a backend dependent definition). This is identical to "row" for backends lacking a blockwise sampling implementation. For those coming from SQL, "row" and "block" correspond to "bernoulli" and "system" respectively in a TABLESAMPLE clause. | `'row'` | +| seed | [int](`int`) \| None | An optional random seed to use, for repeatable sampling. The range of possible seed values is backend specific (most support at least `[0, 2**31 - 1]`). Backends that never support specifying a seed for repeatable sampling will error appropriately. Note that some backends (like DuckDB) do support specifying a seed, but may still not have repeatable results in all cases. | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|----------------------------------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | The input table, with `fraction` of rows selected. | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.memtable({"x": [1, 2, 3, 4], "y": ["a", "b", "c", "d"]}) +>>> t +┏━━━━━━━┳━━━━━━━━┓ +┃ x ┃ y ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ a │ +│ 2 │ b │ +│ 3 │ c │ +│ 4 │ d │ +└───────┴────────┘ +``` + +Sample approximately half the rows, with a seed specified for +reproducibility. + +```python +>>> t.sample(0.5, seed=1234) +┏━━━━━━━┳━━━━━━━━┓ +┃ x ┃ y ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 2 │ b │ +│ 3 │ c │ +└───────┴────────┘ +``` + +### select { #letsql.vendor.ibis.expr.types.relations.Table.select } + +```python +select(*exprs, **named_exprs) +``` + +Compute a new table expression using `exprs` and `named_exprs`. + +Passing an aggregate function to this method will broadcast the +aggregate's value over the number of rows in the table and +automatically constructs a window function expression. See the examples +section for more details. + +For backwards compatibility the keyword argument `exprs` is reserved +and cannot be used to name an expression. This behavior will be removed +in v4. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|-------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------|-----------| +| exprs | [ir](`letsql.vendor.ibis.expr.types`).[Value](`letsql.vendor.ibis.expr.types.Value`) \| [str](`str`) \| [Iterable](`collections.abc.Iterable`)\[[ir](`letsql.vendor.ibis.expr.types`).[Value](`letsql.vendor.ibis.expr.types.Value`) \| [str](`str`)\] | Column expression, string, or list of column expressions and strings. | `()` | +| named_exprs | [ir](`letsql.vendor.ibis.expr.types`).[Value](`letsql.vendor.ibis.expr.types.Value`) \| [str](`str`) | Column expressions | `{}` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | Table expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch() +>>> t +┏━━━━━━━━━┳━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━┓ +┃ species ┃ island ┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ … ┃ +┡━━━━━━━━━╇━━━━━━━━━━━╇━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━┩ +│ string │ string │ float64 │ float64 │ float64 │ … │ +├─────────┼───────────┼────────────────┼───────────────┼───────────────────┼───┤ +│ Adelie │ Torgersen │ 39.1 │ 18.7 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.5 │ 17.4 │ 186.0 │ … │ +│ Adelie │ Torgersen │ 40.3 │ 18.0 │ 195.0 │ … │ +│ Adelie │ Torgersen │ NULL │ NULL │ NULL │ … │ +│ Adelie │ Torgersen │ 36.7 │ 19.3 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 39.3 │ 20.6 │ 190.0 │ … │ +│ Adelie │ Torgersen │ 38.9 │ 17.8 │ 181.0 │ … │ +│ Adelie │ Torgersen │ 39.2 │ 19.6 │ 195.0 │ … │ +│ Adelie │ Torgersen │ 34.1 │ 18.1 │ 193.0 │ … │ +│ Adelie │ Torgersen │ 42.0 │ 20.2 │ 190.0 │ … │ +│ … │ … │ … │ … │ … │ … │ +└─────────┴───────────┴────────────────┴───────────────┴───────────────────┴───┘ +``` + +Simple projection + +```python +>>> t.select("island", "bill_length_mm").head() +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┓ +┃ island ┃ bill_length_mm ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼────────────────┤ +│ Torgersen │ 39.1 │ +│ Torgersen │ 39.5 │ +│ Torgersen │ 40.3 │ +│ Torgersen │ NULL │ +│ Torgersen │ 36.7 │ +└───────────┴────────────────┘ +``` + +In that simple case, you could also just use python's indexing syntax + +```python +>>> t[["island", "bill_length_mm"]].head() +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━┓ +┃ island ┃ bill_length_mm ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼────────────────┤ +│ Torgersen │ 39.1 │ +│ Torgersen │ 39.5 │ +│ Torgersen │ 40.3 │ +│ Torgersen │ NULL │ +│ Torgersen │ 36.7 │ +└───────────┴────────────────┘ +``` + +Projection by zero-indexed column position + +```python +>>> t.select(t[0], t[4]).head() +┏━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┓ +┃ species ┃ flipper_length_mm ┃ +┡━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├─────────┼───────────────────┤ +│ Adelie │ 181.0 │ +│ Adelie │ 186.0 │ +│ Adelie │ 195.0 │ +│ Adelie │ NULL │ +│ Adelie │ 193.0 │ +└─────────┴───────────────────┘ +``` + +Projection with renaming and compute in one call + +```python +>>> t.select(next_year=t.year + 1).head() +┏━━━━━━━━━━━┓ +┃ next_year ┃ +┡━━━━━━━━━━━┩ +│ int64 │ +├───────────┤ +│ 2008 │ +│ 2008 │ +│ 2008 │ +│ 2008 │ +│ 2008 │ +└───────────┘ +``` + +You can do the same thing with a named expression, and using the +deferred API + +```python +>>> from letsql import _ +>>> t.select((_.year + 1).name("next_year")).head() +┏━━━━━━━━━━━┓ +┃ next_year ┃ +┡━━━━━━━━━━━┩ +│ int64 │ +├───────────┤ +│ 2008 │ +│ 2008 │ +│ 2008 │ +│ 2008 │ +│ 2008 │ +└───────────┘ +``` + +Projection with aggregation expressions + +```python +>>> t.select("island", bill_mean=t.bill_length_mm.mean()).head() +┏━━━━━━━━━━━┳━━━━━━━━━━━┓ +┃ island ┃ bill_mean ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼───────────┤ +│ Torgersen │ 43.92193 │ +│ Torgersen │ 43.92193 │ +│ Torgersen │ 43.92193 │ +│ Torgersen │ 43.92193 │ +│ Torgersen │ 43.92193 │ +└───────────┴───────────┘ +``` + +Projection with a selector + +```python +>>> import letsql.selectors as s +>>> t.select(s.numeric() & ~s.cols("year")).head() +┏━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┓ +┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ body_mass_g ┃ +┡━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━┩ +│ float64 │ float64 │ float64 │ float64 │ +├────────────────┼───────────────┼───────────────────┼─────────────┤ +│ 39.1 │ 18.7 │ 181.0 │ 3750.0 │ +│ 39.5 │ 17.4 │ 186.0 │ 3800.0 │ +│ 40.3 │ 18.0 │ 195.0 │ 3250.0 │ +│ NULL │ NULL │ NULL │ NULL │ +│ 36.7 │ 19.3 │ 193.0 │ 3450.0 │ +└────────────────┴───────────────┴───────────────────┴─────────────┘ +``` + +Projection + aggregation across multiple columns + +```python +>>> from letsql import _ +>>> t.select(s.across(s.numeric() & ~s.cols("year"), _.mean())).head() +┏━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━┓ +┃ bill_length_mm ┃ bill_depth_mm ┃ flipper_length_mm ┃ body_mass_g ┃ +┡━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━┩ +│ float64 │ float64 │ float64 │ float64 │ +├────────────────┼───────────────┼───────────────────┼─────────────┤ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +│ 43.92193 │ 17.15117 │ 200.915205 │ 4201.754386 │ +└────────────────┴───────────────┴───────────────────┴─────────────┘ +``` + +### sql { #letsql.vendor.ibis.expr.types.relations.Table.sql } + +```python +sql(query, dialect=None) +``` + +Run a SQL query against a table expression. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------|----------------------|----------------------------------------------------------------------------------------------|------------| +| query | [str](`str`) | Query string | _required_ | +| dialect | [str](`str`) \| None | Optional string indicating the dialect of `query`. Defaults to the backend's native dialect. | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|----------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | An opaque table expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> from letsql import _ +>>> ls.options.interactive = True +>>> t = ls.examples.penguins.fetch(table_name="penguins") +>>> expr = t.sql( +... """ +... SELECT island, mean(bill_length_mm) AS avg_bill_length +... FROM penguins +... GROUP BY 1 +... ORDER BY 2 DESC +... """ +... ) +>>> expr +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━┓ +┃ island ┃ avg_bill_length ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼─────────────────┤ +│ Biscoe │ 45.257485 │ +│ Dream │ 44.167742 │ +│ Torgersen │ 38.950980 │ +└───────────┴─────────────────┘ +``` + +Mix and match ibis expressions with SQL queries + +```python +>>> t = ls.examples.penguins.fetch(table_name="penguins") +>>> expr = t.sql( +... """ +... SELECT island, mean(bill_length_mm) AS avg_bill_length +... FROM penguins +... GROUP BY 1 +... ORDER BY 2 DESC +... """ +... ) +>>> expr = expr.mutate( +... island=_.island.lower(), +... avg_bill_length=_.avg_bill_length.round(1), +... ) +>>> expr +┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━┓ +┃ island ┃ avg_bill_length ┃ +┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├───────────┼─────────────────┤ +│ biscoe │ 45.3 │ +│ torgersen │ 39.0 │ +│ dream │ 44.2 │ +└───────────┴─────────────────┘ +``` + +Because ibis expressions aren't named, they aren't visible to +subsequent `.sql` calls. Use the [`alias`](#ibis.expr.types.relations.Table.alias) method +to assign a name to an expression. + +```python +>>> expr.alias("b").sql("SELECT * FROM b WHERE avg_bill_length > 40") +┏━━━━━━━━┳━━━━━━━━━━━━━━━━━┓ +┃ island ┃ avg_bill_length ┃ +┡━━━━━━━━╇━━━━━━━━━━━━━━━━━┩ +│ string │ float64 │ +├────────┼─────────────────┤ +│ biscoe │ 45.3 │ +│ dream │ 44.2 │ +└────────┴─────────────────┘ +``` + +#### See Also {.doc-section .doc-section-see-also} + +[`Table.alias`](#ibis.expr.types.relations.Table.alias) + +### union { #letsql.vendor.ibis.expr.types.relations.Table.union } + +```python +union(table, *rest, distinct=False) +``` + +Compute the set union of multiple table expressions. + +The input tables must have identical schemas. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|----------------------------------------------------------|------------------------------|------------| +| table | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | A table expression | _required_ | +| *rest | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | Additional table expressions | `()` | +| distinct | [bool](`bool`) | Only return distinct rows | `False` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|-------------------------------------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | A new table containing the union of all input tables. | + +#### See Also {.doc-section .doc-section-see-also} + +[`ibis.union`](./expression-tables.qmd#ibis.union) + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> ls.options.interactive = True +>>> t1 = ls.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = ls.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> t1.union(t2) # union all by default doctest: +SKIP +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +│ 1 │ +│ 2 │ +└───────┘ +>>> t1.union(t2, distinct=True).order_by("a") +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +│ 3 │ +└───────┘ +``` + +### view { #letsql.vendor.ibis.expr.types.relations.Table.view } + +```python +view() +``` + +Create a new table expression distinct from the current one. + +Use this API for any self-referencing operations like a self-join. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------|------------------| +| | [Table](`letsql.vendor.ibis.expr.types.relations.Table`) | Table expression | + +### cache { #letsql.vendor.ibis.expr.types.relations.Table.cache } + +```python +cache(storage=None) +``` + +Cache the results of a computation to improve performance on subsequent executions. +This method allows you to cache the results of a computation either in memory, on disk +using Parquet files, or in a database table. The caching strategy and storage location +are determined by the storage parameter. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------|--------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------| +| storage | [CacheStorage](`CacheStorage`) | The storage strategy to use for caching. Can be one of: - ParquetCacheStorage: Caches results as Parquet files on disk - SourceStorage: Caches results in the source database - ParquetSnapshot: Creates a snapshot of data in Parquet format - SnapshotStorage: Creates a snapshot in the source database If None, uses the default storage configuration. | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|---------------------------------------------------|----------------------------------------------------------| +| | [Expr](`letsql.vendor.ibis.expr.types.core.Expr`) | A new expression that represents the cached computation. | + +#### Notes {.doc-section .doc-section-notes} + +The cache method supports two main strategies: +1. ModificationTimeStrategy: Tracks changes based on modification time +2. SnapshotStrategy: Creates point-in-time snapshots of the data + +Each strategy can be combined with either Parquet or database storage. + +#### Examples {.doc-section .doc-section-examples} + +Using ParquetCacheStorage: + +```python +>>> import letsql as ls +>>> from letsql.common.caching import ParquetCacheStorage +>>> from pathlib import Path +>>> pg = ls.postgres.connect_examples() +>>> con = ls.connect() +>>> storage = ParquetCacheStorage(source=con, path=Path.cwd()) +>>> alltypes = pg.table("functional_alltypes") +>>> cached = (alltypes +... .select(alltypes.smallint_col, alltypes.int_col, alltypes.float_col) +... .cache(storage=storage)) +``` + +Using SourceStorage with PostgreSQL: + +```python +>>> from letsql.common.caching import SourceStorage +>>> from letsql import _ +>>> ddb = ls.duckdb.connect() +>>> path = ls.config.options.pins.get_path("batting") +>>> right = (ddb.read_parquet(path, table_name="batting") +... .filter(_.yearID == 2014) +... .pipe(con.register, table_name="ddb-batting")) +>>> left = (pg.table("batting") +... .filter(_.yearID == 2015) +... .pipe(con.register, table_name="pg-batting")) +>>> # Cache the joined result +>>> expr = left.join(right, "playerID").cache(SourceStorage(source=pg)) +``` + +Using cache with filtering: + +```python +>>> cached = alltypes.cache(storage=storage) +>>> expr = cached.filter([ +... cached.float_col > 0, +... cached.smallint_col > 4, +... cached.int_col < cached.float_col * 2 +... ]) +``` + +#### See Also {.doc-section .doc-section-see-also} + +ParquetCacheStorage : Storage implementation for Parquet files +SourceStorage : Storage implementation for database tables +ModificationTimeStrategy : Strategy for tracking changes by modification time +SnapshotStrategy : Strategy for creating data snapshots + +#### Notes {.doc-section .doc-section-notes} + +- The cache is identified by a unique key based on the computation and strategy +- Cache invalidation is handled automatically based on the chosen strategy +- Cross-source caching (e.g., from PostgreSQL to DuckDB) is supported +- Cache locations can be configured globally through letsql.config.options + +### into_backend { #letsql.vendor.ibis.expr.types.relations.Table.into_backend } + +```python +into_backend(con, name=None) +``` + +Converts the Expr to a table in the given backend `con` with an optional table name `name`. + +The table is backed by a PyArrow RecordBatchReader, the RecordBatchReader is teed +so it can safely be reaused without spilling to disk. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------|-----------------------------------------------|------------| +| con | | The backend where the table should be created | _required_ | +| name | | The name of the table | `None` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> from letsql import _ +>>> ls.options.interactive = True +>>> ls_con = ls.connect() +>>> pg_con = ls.postgres.connect_examples() +>>> t = pg_con.table("batting").into_backend(ls_con, "ls_batting") +>>> expr = ( +... t.join(t, "playerID") +... .order_by("playerID", "yearID") +... .limit(15) +... .select(player_id="playerID", year_id="yearID_right") +... ) +>>> expr +┏━━━━━━━━━━━┳━━━━━━━━━┓ +┃ player_id ┃ year_id ┃ +┡━━━━━━━━━━━╇━━━━━━━━━┩ +│ string │ int64 │ +├───────────┼─────────┤ +│ aardsda01 │ 2015 │ +│ aardsda01 │ 2007 │ +│ aardsda01 │ 2006 │ +│ aardsda01 │ 2009 │ +│ aardsda01 │ 2008 │ +│ aardsda01 │ 2010 │ +│ aardsda01 │ 2004 │ +│ aardsda01 │ 2013 │ +│ aardsda01 │ 2012 │ +│ aardsda01 │ 2006 │ +│ … │ … │ +└───────────┴─────────┘ +``` \ No newline at end of file diff --git a/docs/reference/expression-strings.qmd b/docs/reference/expression-strings.qmd new file mode 100644 index 00000000..e27fcd6f --- /dev/null +++ b/docs/reference/expression-strings.qmd @@ -0,0 +1,1396 @@ +# String expressions + +All string operations are valid for both scalars and columns. + +# StringValue { #letsql.vendor.ibis.expr.types.strings.StringValue } + +```python +StringValue(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [ascii_str](#letsql.vendor.ibis.expr.types.strings.StringValue.ascii_str) | Return the numeric ASCII code of the first character of a string. | +| [authority](#letsql.vendor.ibis.expr.types.strings.StringValue.authority) | Parse a URL and extract authority. | +| [capitalize](#letsql.vendor.ibis.expr.types.strings.StringValue.capitalize) | Uppercase the first letter, lowercase the rest. | +| [concat](#letsql.vendor.ibis.expr.types.strings.StringValue.concat) | Concatenate strings. | +| [contains](#letsql.vendor.ibis.expr.types.strings.StringValue.contains) | Return whether the expression contains `substr`. | +| [endswith](#letsql.vendor.ibis.expr.types.strings.StringValue.endswith) | Determine if `self` ends with `end`. | +| [find](#letsql.vendor.ibis.expr.types.strings.StringValue.find) | Return the position of the first occurrence of substring. | +| [find_in_set](#letsql.vendor.ibis.expr.types.strings.StringValue.find_in_set) | Find the first occurrence of `str_list` within a list of strings. | +| [fragment](#letsql.vendor.ibis.expr.types.strings.StringValue.fragment) | Parse a URL and extract fragment identifier. | +| [host](#letsql.vendor.ibis.expr.types.strings.StringValue.host) | Parse a URL and extract host. | +| [length](#letsql.vendor.ibis.expr.types.strings.StringValue.length) | Compute the length of a string. | +| [levenshtein](#letsql.vendor.ibis.expr.types.strings.StringValue.levenshtein) | Return the Levenshtein distance between two strings. | +| [lower](#letsql.vendor.ibis.expr.types.strings.StringValue.lower) | Convert string to all lowercase. | +| [lpad](#letsql.vendor.ibis.expr.types.strings.StringValue.lpad) | Pad `arg` by truncating on the right or padding on the left. | +| [lstrip](#letsql.vendor.ibis.expr.types.strings.StringValue.lstrip) | Remove whitespace from the left side of string. | +| [path](#letsql.vendor.ibis.expr.types.strings.StringValue.path) | Parse a URL and extract path. | +| [protocol](#letsql.vendor.ibis.expr.types.strings.StringValue.protocol) | Parse a URL and extract protocol. | +| [query](#letsql.vendor.ibis.expr.types.strings.StringValue.query) | Parse a URL and returns query string or query string parameter. | +| [re_extract](#letsql.vendor.ibis.expr.types.strings.StringValue.re_extract) | Return the specified match at `index` from a regex `pattern`. | +| [re_replace](#letsql.vendor.ibis.expr.types.strings.StringValue.re_replace) | Replace all matches found by regex `pattern` with `replacement`. | +| [re_search](#letsql.vendor.ibis.expr.types.strings.StringValue.re_search) | Return whether the values match `pattern`. | +| [re_split](#letsql.vendor.ibis.expr.types.strings.StringValue.re_split) | Split a string by a regular expression `pattern`. | +| [repeat](#letsql.vendor.ibis.expr.types.strings.StringValue.repeat) | Repeat a string `n` times. | +| [replace](#letsql.vendor.ibis.expr.types.strings.StringValue.replace) | Replace each exact match of `pattern` with `replacement`. | +| [reverse](#letsql.vendor.ibis.expr.types.strings.StringValue.reverse) | Reverse the characters of a string. | +| [right](#letsql.vendor.ibis.expr.types.strings.StringValue.right) | Return up to `nchars` from the end of each string. | +| [rpad](#letsql.vendor.ibis.expr.types.strings.StringValue.rpad) | Pad `self` by truncating or padding on the right. | +| [rstrip](#letsql.vendor.ibis.expr.types.strings.StringValue.rstrip) | Remove whitespace from the right side of string. | +| [split](#letsql.vendor.ibis.expr.types.strings.StringValue.split) | Split as string on `delimiter`. | +| [startswith](#letsql.vendor.ibis.expr.types.strings.StringValue.startswith) | Determine whether `self` starts with `start`. | +| [strip](#letsql.vendor.ibis.expr.types.strings.StringValue.strip) | Remove whitespace from left and right sides of a string. | +| [substr](#letsql.vendor.ibis.expr.types.strings.StringValue.substr) | Extract a substring. | +| [to_date](#letsql.vendor.ibis.expr.types.strings.StringValue.to_date) | | +| [translate](#letsql.vendor.ibis.expr.types.strings.StringValue.translate) | Replace `from_str` characters in `self` characters in `to_str`. | +| [upper](#letsql.vendor.ibis.expr.types.strings.StringValue.upper) | Convert string to all uppercase. | +| [userinfo](#letsql.vendor.ibis.expr.types.strings.StringValue.userinfo) | Parse a URL and extract user info. | + +### ascii_str { #letsql.vendor.ibis.expr.types.strings.StringValue.ascii_str } + +```python +ascii_str() +``` + +Return the numeric ASCII code of the first character of a string. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|------------------------------------------------| +| | [IntegerValue](`letsql.vendor.ibis.expr.types.numeric.IntegerValue`) | ASCII code of the first character of the input | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "def", "ghi"]}) +>>> t.s.ascii_str() +┏━━━━━━━━━━━━━━━━┓ +┃ StringAscii(s) ┃ +┡━━━━━━━━━━━━━━━━┩ +│ int32 │ +├────────────────┤ +│ 97 │ +│ 100 │ +│ 103 │ +└────────────────┘ +``` + +### authority { #letsql.vendor.ibis.expr.types.strings.StringValue.authority } + +```python +authority() +``` + +Parse a URL and extract authority. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> url = ibis.literal("https://user:pass@example.com:80/docs/books") +>>> result = url.authority() # user:pass@example.com:80 +``` + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Extracted string value | + +### capitalize { #letsql.vendor.ibis.expr.types.strings.StringValue.capitalize } + +```python +capitalize() +``` + +Uppercase the first letter, lowercase the rest. + +This API matches the semantics of the Python [](`str.capitalize`) +method. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|--------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Capitalized string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["aBC", " abc", "ab cd", None]}) +>>> t.s.capitalize() +┏━━━━━━━━━━━━━━━┓ +┃ Capitalize(s) ┃ +┡━━━━━━━━━━━━━━━┩ +│ string │ +├───────────────┤ +│ Abc │ +│ abc │ +│ Ab cd │ +│ NULL │ +└───────────────┘ +``` + +### concat { #letsql.vendor.ibis.expr.types.strings.StringValue.concat } + +```python +concat(other, *args) +``` + +Concatenate strings. + +NULLs are propagated. This methods is equivalent to using the `+` operator. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------|-----------------------------------|------------| +| other | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | String to concatenate | _required_ | +| args | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Additional strings to concatenate | `()` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|--------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | All strings concatenated | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", None]}) +>>> t.s.concat("xyz", "123") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringConcat((s, 'xyz', '123')) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────────────────────┤ +│ abcxyz123 │ +│ NULL │ +└─────────────────────────────────┘ +>>> t.s + "xyz" +┏━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringConcat((s, 'xyz')) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├──────────────────────────┤ +│ abcxyz │ +│ NULL │ +└──────────────────────────┘ +``` + +### contains { #letsql.vendor.ibis.expr.types.strings.StringValue.contains } + +```python +contains(substr) +``` + +Return whether the expression contains `substr`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------|------------------------------|------------| +| substr | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Substring for which to check | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|---------------------------------------------------------------| +| | [BooleanValue](`letsql.vendor.ibis.expr.types.logical.BooleanValue`) | Boolean indicating the presence of `substr` in the expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["bab", "ddd", "eaf"]}) +>>> t.s.contains("a") +┏━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringContains(s, 'a') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├────────────────────────┤ +│ True │ +│ False │ +│ True │ +└────────────────────────┘ +``` + +### endswith { #letsql.vendor.ibis.expr.types.strings.StringValue.endswith } + +```python +endswith(end) +``` + +Determine if `self` ends with `end`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------|---------------------|------------| +| end | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Suffix to check for | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|---------------------------------------------------| +| | [BooleanValue](`letsql.vendor.ibis.expr.types.logical.BooleanValue`) | Boolean indicating whether `self` ends with `end` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["Ibis project", "GitHub"]}) +>>> t.s.endswith("project") +┏━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ EndsWith(s, 'project') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├────────────────────────┤ +│ True │ +│ False │ +└────────────────────────┘ +``` + +### find { #letsql.vendor.ibis.expr.types.strings.StringValue.find } + +```python +find(substr, start=None, end=None) +``` + +Return the position of the first occurrence of substring. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|----------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------|------------| +| substr | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Substring to search for | _required_ | +| start | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) \| None | Zero based index of where to start the search | `None` | +| end | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) \| None | Zero based index of where to stop the search. Currently not implemented. | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|-----------------------------------------------------| +| | [IntegerValue](`letsql.vendor.ibis.expr.types.numeric.IntegerValue`) | Position of `substr` in `arg` starting from `start` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "bac", "bca"]}) +>>> t.s.find("a") +┏━━━━━━━━━━━━━━━━━━━━┓ +┃ StringFind(s, 'a') ┃ +┡━━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ +├────────────────────┤ +│ 0 │ +│ 1 │ +│ 2 │ +└────────────────────┘ +>>> t.s.find("z") +┏━━━━━━━━━━━━━━━━━━━━┓ +┃ StringFind(s, 'z') ┃ +┡━━━━━━━━━━━━━━━━━━━━┩ +│ int64 │ +├────────────────────┤ +│ -1 │ +│ -1 │ +│ -1 │ +└────────────────────┘ +``` + +### find_in_set { #letsql.vendor.ibis.expr.types.strings.StringValue.find_in_set } + +```python +find_in_set(str_list) +``` + +Find the first occurrence of `str_list` within a list of strings. + +No string in `str_list` can have a comma. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|--------------------------------------------------------|---------------------|------------| +| str_list | [Sequence](`collections.abc.Sequence`)\[[str](`str`)\] | Sequence of strings | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|-------------------------------------------------------------------------------------------------| +| | [IntegerValue](`letsql.vendor.ibis.expr.types.numeric.IntegerValue`) | Position of `str_list` in `self`. Returns -1 if `self` isn't found or if `self` contains `','`. | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> table = ibis.table(dict(string_col="string")) +>>> result = table.string_col.find_in_set(["a", "b"]) +``` + +### fragment { #letsql.vendor.ibis.expr.types.strings.StringValue.fragment } + +```python +fragment() +``` + +Parse a URL and extract fragment identifier. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> url = ibis.literal("https://example.com:80/docs/#DOWNLOADING") +>>> result = url.fragment() # DOWNLOADING +``` + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Extracted string value | + +### host { #letsql.vendor.ibis.expr.types.strings.StringValue.host } + +```python +host() +``` + +Parse a URL and extract host. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> url = ibis.literal("https://user:pass@example.com:80/docs/books") +>>> result = url.host() # example.com +``` + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Extracted string value | + +### length { #letsql.vendor.ibis.expr.types.strings.StringValue.length } + +```python +length() +``` + +Compute the length of a string. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|---------------------------------------------| +| | [IntegerValue](`letsql.vendor.ibis.expr.types.numeric.IntegerValue`) | The length of each string in the expression | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["aaa", "a", "aa"]}) +>>> t.s.length() +┏━━━━━━━━━━━━━━━━━┓ +┃ StringLength(s) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ int32 │ +├─────────────────┤ +│ 3 │ +│ 1 │ +│ 2 │ +└─────────────────┘ +``` + +### levenshtein { #letsql.vendor.ibis.expr.types.strings.StringValue.levenshtein } + +```python +levenshtein(other) +``` + +Return the Levenshtein distance between two strings. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------------------|----------------------|------------| +| other | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | String to compare to | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|-------------------------------------------| +| | [IntegerValue](`letsql.vendor.ibis.expr.types.numeric.IntegerValue`) | The edit distance between the two strings | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> s = ibis.literal("kitten") +>>> s.levenshtein("sitting") +┌───┐ +│ 3 │ +└───┘ +``` + +### lower { #letsql.vendor.ibis.expr.types.strings.StringValue.lower } + +```python +lower() +``` + +Convert string to all lowercase. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Lowercase string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["AAA", "a", "AA"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ AAA │ +│ a │ +│ AA │ +└────────┘ +>>> t.s.lower() +┏━━━━━━━━━━━━━━┓ +┃ Lowercase(s) ┃ +┡━━━━━━━━━━━━━━┩ +│ string │ +├──────────────┤ +│ aaa │ +│ a │ +│ aa │ +└──────────────┘ +``` + +### lpad { #letsql.vendor.ibis.expr.types.strings.StringValue.lpad } + +```python +lpad(length, pad=' ') +``` + +Pad `arg` by truncating on the right or padding on the left. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------------------------------------------------------------------|-------------------------|------------| +| length | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) | Length of output string | _required_ | +| pad | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Pad character | `' '` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|--------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Left-padded string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "def", "ghij"]}) +>>> t.s.lpad(5, "-") +┏━━━━━━━━━━━━━━━━━┓ +┃ LPad(s, 5, '-') ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────┤ +│ --abc │ +│ --def │ +│ -ghij │ +└─────────────────┘ +``` + +### lstrip { #letsql.vendor.ibis.expr.types.strings.StringValue.lstrip } + +```python +lstrip() +``` + +Remove whitespace from the left side of string. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|----------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Left-stripped string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["\ta\t", "\nb\n", "\vc\t"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ \ta\t │ +│ \nb\n │ +│ \vc\t │ +└────────┘ +>>> t.s.lstrip() +┏━━━━━━━━━━━┓ +┃ LStrip(s) ┃ +┡━━━━━━━━━━━┩ +│ string │ +├───────────┤ +│ a\t │ +│ b\n │ +│ c\t │ +└───────────┘ +``` + +### path { #letsql.vendor.ibis.expr.types.strings.StringValue.path } + +```python +path() +``` + +Parse a URL and extract path. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> url = ibis.literal( +... "https://example.com:80/docs/books/tutorial/index.html?name=networking" +... ) +>>> result = url.path() # docs/books/tutorial/index.html +``` + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Extracted string value | + +### protocol { #letsql.vendor.ibis.expr.types.strings.StringValue.protocol } + +```python +protocol() +``` + +Parse a URL and extract protocol. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> url = ibis.literal("https://user:pass@example.com:80/docs/books") +>>> result = url.protocol() # https +``` + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Extracted string value | + +### query { #letsql.vendor.ibis.expr.types.strings.StringValue.query } + +```python +query(key=None) +``` + +Parse a URL and returns query string or query string parameter. + +If key is passed, return the value of the query string parameter named. +If key is absent, return the query string. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------------------------------------------|----------------------------|-----------| +| key | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) \| None | Query component to extract | `None` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> url = ibis.literal( +... "https://example.com:80/docs/books/tutorial/index.html?name=networking" +... ) +>>> result = url.query() # name=networking +>>> query_name = url.query("name") # networking +``` + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Extracted string value | + +### re_extract { #letsql.vendor.ibis.expr.types.strings.StringValue.re_extract } + +```python +re_extract(pattern, index) +``` + +Return the specified match at `index` from a regex `pattern`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------|--------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------| +| pattern | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Regular expression pattern string | _required_ | +| index | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) | The index of the match group to return. The behavior of this function follows the behavior of Python's [`match objects`](https://docs.python.org/3/library/re.html#match-objects): when `index` is zero and there's a match, return the entire match, otherwise return the content of the `index`-th match group. | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|----------------------------------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Extracted match or whole string if `index` is zero | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "bac", "bca"]}) +``` + +Extract a specific group + +```python +>>> t.s.re_extract(r"^(a)bc", 1) +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexExtract(s, '^(a)bc', 1) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├──────────────────────────────┤ +│ a │ +│ ~ │ +│ ~ │ +└──────────────────────────────┘ +``` + +Extract the entire match + +```python +>>> t.s.re_extract(r"^(a)bc", 0) +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexExtract(s, '^(a)bc', 0) ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├──────────────────────────────┤ +│ abc │ +│ ~ │ +│ ~ │ +└──────────────────────────────┘ +``` + +### re_replace { #letsql.vendor.ibis.expr.types.strings.StringValue.re_replace } + +```python +re_replace(pattern, replacement) +``` + +Replace all matches found by regex `pattern` with `replacement`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|-------------|------------------------------------------------------------------------------------|------------------------------------------|------------| +| pattern | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Regular expression string | _required_ | +| replacement | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Replacement string or regular expression | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|-----------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Modified string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "bac", "bca", "this has multi \t whitespace"]}) +>>> s = t.s +``` + +Replace all "a"s that are at the beginning of the string with "b": + +```python +>>> s.re_replace("^a", "b") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexReplace(s, '^a', 'b') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├───────────────────────────────┤ +│ bbc │ +│ bac │ +│ bca │ +│ this has multi \t whitespace │ +└───────────────────────────────┘ +``` + +Double up any "a"s or "b"s, using capture groups and backreferences: + +```python +>>> s.re_replace("([ab])", r"\0\0") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexReplace(s, '()', '\\0\\0') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────────────────────────┤ +│ aabbc │ +│ bbaac │ +│ bbcaa │ +│ this haas multi \t whitespaace │ +└─────────────────────────────────────┘ +``` + +Normalize all whitespace to a single space: + +```python +>>> s.re_replace(r"\s+", " ") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexReplace(s, '\\s+', ' ') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├──────────────────────────────┤ +│ abc │ +│ bac │ +│ bca │ +│ this has multi whitespace │ +└──────────────────────────────┘ +``` + +### re_search { #letsql.vendor.ibis.expr.types.strings.StringValue.re_search } + +```python +re_search(pattern) +``` + +Return whether the values match `pattern`. + +Returns `True` if the regex matches a string and `False` otherwise. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------|------------------------------------------------------------------------------------|--------------------------------------|------------| +| pattern | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Regular expression use for searching | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|----------------------| +| | [BooleanValue](`letsql.vendor.ibis.expr.types.logical.BooleanValue`) | Indicator of matches | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["Ibis project", "GitHub"]}) +>>> t.s.re_search(".+Hub") +┏━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ RegexSearch(s, '.+Hub') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├─────────────────────────┤ +│ False │ +│ True │ +└─────────────────────────┘ +``` + +### re_split { #letsql.vendor.ibis.expr.types.strings.StringValue.re_split } + +```python +re_split(pattern) +``` + +Split a string by a regular expression `pattern`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------|------------------------------------------------------------------------------------|---------------------------------------|------------| +| pattern | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Regular expression string to split by | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|-----------------------------------------------------------------|----------------------------------------------| +| | [ArrayValue](`letsql.vendor.ibis.expr.types.arrays.ArrayValue`) | Array of strings from splitting by `pattern` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable(dict(s=["a.b", "b.....c", "c.........a", "def"])) +>>> t.s +┏━━━━━━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━━━━━━┩ +│ string │ +├─────────────┤ +│ a.b │ +│ b.....c │ +│ c.........a │ +│ def │ +└─────────────┘ +>>> t.s.re_split(r"\.+").name("splits") +┏━━━━━━━━━━━━━━━━━━━━━━┓ +┃ splits ┃ +┡━━━━━━━━━━━━━━━━━━━━━━┩ +│ array │ +├──────────────────────┤ +│ ['a', 'b'] │ +│ ['b', 'c'] │ +│ ['c', 'a'] │ +│ ['def'] │ +└──────────────────────┘ +``` + +### repeat { #letsql.vendor.ibis.expr.types.strings.StringValue.repeat } + +```python +repeat(n) +``` + +Repeat a string `n` times. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------------------------------------------------------------------|-----------------------|------------| +| n | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) | Number of repetitions | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|-----------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Repeated string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["a", "bb", "c"]}) +>>> t.s.repeat(5) +┏━━━━━━━━━━━━━━┓ +┃ Repeat(s, 5) ┃ +┡━━━━━━━━━━━━━━┩ +│ string │ +├──────────────┤ +│ aaaaa │ +│ bbbbbbbbbb │ +│ ccccc │ +└──────────────┘ +``` + +### replace { #letsql.vendor.ibis.expr.types.strings.StringValue.replace } + +```python +replace(pattern, replacement) +``` + +Replace each exact match of `pattern` with `replacement`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|-------------|--------------------------------------------------------------------|--------------------|------------| +| pattern | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | String pattern | _required_ | +| replacement | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | String replacement | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|-----------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Replaced string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "bac", "bca"]}) +>>> t.s.replace("b", "z") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringReplace(s, 'b', 'z') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├────────────────────────────┤ +│ azc │ +│ zac │ +│ zca │ +└────────────────────────────┘ +``` + +### reverse { #letsql.vendor.ibis.expr.types.strings.StringValue.reverse } + +```python +reverse() +``` + +Reverse the characters of a string. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|-----------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Reversed string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "def", "ghi"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ abc │ +│ def │ +│ ghi │ +└────────┘ +>>> t.s.reverse() +┏━━━━━━━━━━━━┓ +┃ Reverse(s) ┃ +┡━━━━━━━━━━━━┩ +│ string │ +├────────────┤ +│ cba │ +│ fed │ +│ ihg │ +└────────────┘ +``` + +### right { #letsql.vendor.ibis.expr.types.strings.StringValue.right } + +```python +right(nchars) +``` + +Return up to `nchars` from the end of each string. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------------------------------------------------------------------|----------------------------------------|------------| +| nchars | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) | Maximum number of characters to return | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|-------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Characters from the end | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "defg", "hijlk"]}) +>>> t.s.right(2) +┏━━━━━━━━━━━━━━━━┓ +┃ StrRight(s, 2) ┃ +┡━━━━━━━━━━━━━━━━┩ +│ string │ +├────────────────┤ +│ bc │ +│ fg │ +│ lk │ +└────────────────┘ +``` + +### rpad { #letsql.vendor.ibis.expr.types.strings.StringValue.rpad } + +```python +rpad(length, pad=' ') +``` + +Pad `self` by truncating or padding on the right. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------------------------------------------------------------------|-------------------------|------------| +| self | | String to pad | _required_ | +| length | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) | Length of output string | _required_ | +| pad | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Pad character | `' '` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|---------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Right-padded string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "def", "ghij"]}) +>>> t.s.rpad(5, "-") +┏━━━━━━━━━━━━━━━━━┓ +┃ RPad(s, 5, '-') ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────┤ +│ abc-- │ +│ def-- │ +│ ghij- │ +└─────────────────┘ +``` + +### rstrip { #letsql.vendor.ibis.expr.types.strings.StringValue.rstrip } + +```python +rstrip() +``` + +Remove whitespace from the right side of string. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|-----------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Right-stripped string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["\ta\t", "\nb\n", "\vc\t"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ \ta\t │ +│ \nb\n │ +│ \vc\t │ +└────────┘ +>>> t.s.rstrip() +┏━━━━━━━━━━━┓ +┃ RStrip(s) ┃ +┡━━━━━━━━━━━┩ +│ string │ +├───────────┤ +│ \ta │ +│ \nb │ +│ \vc │ +└───────────┘ +``` + +### split { #letsql.vendor.ibis.expr.types.strings.StringValue.split } + +```python +split(delimiter) +``` + +Split as string on `delimiter`. + +::: {.callout-note} +## This API only works on backends with array support. +::: + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|-----------|------------------------------------------------------------------------------------|-------------------|------------| +| delimiter | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Value to split by | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|-----------------------------------------------------------------|---------------------------------| +| | [ArrayValue](`letsql.vendor.ibis.expr.types.arrays.ArrayValue`) | The string split by `delimiter` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"col": ["a,b,c", "d,e", "f"]}) +>>> t +┏━━━━━━━━┓ +┃ col ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ a,b,c │ +│ d,e │ +│ f │ +└────────┘ +>>> t.col.split(",") +┏━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StringSplit(col, ',') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━┩ +│ array │ +├───────────────────────┤ +│ ['a', 'b', ... +1] │ +│ ['d', 'e'] │ +│ ['f'] │ +└───────────────────────┘ +``` + +### startswith { #letsql.vendor.ibis.expr.types.strings.StringValue.startswith } + +```python +startswith(start) +``` + +Determine whether `self` starts with `start`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------|---------------------|------------| +| start | [str](`str`) \| [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | prefix to check for | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|-------------------------------------------------------| +| | [BooleanValue](`letsql.vendor.ibis.expr.types.logical.BooleanValue`) | Boolean indicating whether `self` starts with `start` | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["Ibis project", "GitHub"]}) +>>> t.s.startswith("Ibis") +┏━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ StartsWith(s, 'Ibis') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━┩ +│ boolean │ +├───────────────────────┤ +│ True │ +│ False │ +└───────────────────────┘ +``` + +### strip { #letsql.vendor.ibis.expr.types.strings.StringValue.strip } + +```python +strip() +``` + +Remove whitespace from left and right sides of a string. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|-----------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Stripped string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["\ta\t", "\nb\n", "\vc\t"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ \ta\t │ +│ \nb\n │ +│ \vc\t │ +└────────┘ +>>> t.s.strip() +┏━━━━━━━━━━┓ +┃ Strip(s) ┃ +┡━━━━━━━━━━┩ +│ string │ +├──────────┤ +│ a │ +│ b │ +│ c │ +└──────────┘ +``` + +### substr { #letsql.vendor.ibis.expr.types.strings.StringValue.substr } + +```python +substr(start, length=None) +``` + +Extract a substring. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|----------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------|------------| +| start | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) | First character to start splitting, indices start at 0 | _required_ | +| length | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) \| None | Maximum length of each substring. If not supplied, searches the entire string | `None` | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|-----------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Found substring | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["abc", "defg", "hijlk"]}) +>>> t.s.substr(2) +┏━━━━━━━━━━━━━━━━━┓ +┃ Substring(s, 2) ┃ +┡━━━━━━━━━━━━━━━━━┩ +│ string │ +├─────────────────┤ +│ c │ +│ fg │ +│ jlk │ +└─────────────────┘ +``` + +### to_date { #letsql.vendor.ibis.expr.types.strings.StringValue.to_date } + +```python +to_date(format_str) +``` + + + +### translate { #letsql.vendor.ibis.expr.types.strings.StringValue.translate } + +```python +translate(from_str, to_str) +``` + +Replace `from_str` characters in `self` characters in `to_str`. + +To avoid unexpected behavior, `from_str` should be shorter than +`to_str`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|--------------------------------------------------------------------|-----------------------------------|------------| +| from_str | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Characters in `arg` to replace | _required_ | +| to_str | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Characters to use for replacement | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|-------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Translated string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> table = ibis.table(dict(string_col="string")) +>>> result = table.string_col.translate("a", "b") +``` + +### upper { #letsql.vendor.ibis.expr.types.strings.StringValue.upper } + +```python +upper() +``` + +Convert string to all uppercase. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Uppercase string | + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> ibis.options.interactive = True +>>> t = ibis.memtable({"s": ["aaa", "A", "aa"]}) +>>> t +┏━━━━━━━━┓ +┃ s ┃ +┡━━━━━━━━┩ +│ string │ +├────────┤ +│ aaa │ +│ A │ +│ aa │ +└────────┘ +>>> t.s.upper() +┏━━━━━━━━━━━━━━┓ +┃ Uppercase(s) ┃ +┡━━━━━━━━━━━━━━┩ +│ string │ +├──────────────┤ +│ AAA │ +│ A │ +│ AA │ +└──────────────┘ +``` + +### userinfo { #letsql.vendor.ibis.expr.types.strings.StringValue.userinfo } + +```python +userinfo() +``` + +Parse a URL and extract user info. + +#### Examples {.doc-section .doc-section-examples} + +```python +>>> import ibis +>>> url = ibis.literal("https://user:pass@example.com:80/docs/books") +>>> result = url.userinfo() # user:pass +``` + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | Extracted string value | \ No newline at end of file diff --git a/docs/reference/expression-temporal.qmd b/docs/reference/expression-temporal.qmd new file mode 100644 index 00000000..9195cbb1 --- /dev/null +++ b/docs/reference/expression-temporal.qmd @@ -0,0 +1,313 @@ +# Temporal expressions + +Dates, times, timestamps and intervals. + +# TimeValue { #letsql.vendor.ibis.expr.types.temporal.TimeValue } + +```python +TimeValue(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [hour](#letsql.vendor.ibis.expr.types.temporal.TimeValue.hour) | Extract the hour component. | +| [microsecond](#letsql.vendor.ibis.expr.types.temporal.TimeValue.microsecond) | Extract the microsecond component. | +| [millisecond](#letsql.vendor.ibis.expr.types.temporal.TimeValue.millisecond) | Extract the millisecond component. | +| [minute](#letsql.vendor.ibis.expr.types.temporal.TimeValue.minute) | Extract the minute component. | +| [second](#letsql.vendor.ibis.expr.types.temporal.TimeValue.second) | Extract the second component. | +| [time](#letsql.vendor.ibis.expr.types.temporal.TimeValue.time) | Return the time component of the expression. | +| [truncate](#letsql.vendor.ibis.expr.types.temporal.TimeValue.truncate) | Truncate the expression to a time expression in units of `unit`. | + +### hour { #letsql.vendor.ibis.expr.types.temporal.TimeValue.hour } + +```python +hour() +``` + +Extract the hour component. + +### microsecond { #letsql.vendor.ibis.expr.types.temporal.TimeValue.microsecond } + +```python +microsecond() +``` + +Extract the microsecond component. + +### millisecond { #letsql.vendor.ibis.expr.types.temporal.TimeValue.millisecond } + +```python +millisecond() +``` + +Extract the millisecond component. + +### minute { #letsql.vendor.ibis.expr.types.temporal.TimeValue.minute } + +```python +minute() +``` + +Extract the minute component. + +### second { #letsql.vendor.ibis.expr.types.temporal.TimeValue.second } + +```python +second() +``` + +Extract the second component. + +### time { #letsql.vendor.ibis.expr.types.temporal.TimeValue.time } + +```python +time() +``` + +Return the time component of the expression. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|-----------------------------------------------------------------|------------------------------| +| | [TimeValue](`letsql.vendor.ibis.expr.types.temporal.TimeValue`) | The time component of `self` | + +### truncate { #letsql.vendor.ibis.expr.types.temporal.TimeValue.truncate } + +```python +truncate(unit) +``` + +Truncate the expression to a time expression in units of `unit`. + +Commonly used for time series resampling. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|----------------------------------------------------------------------------|-------------------------|------------| +| unit | [Literal](`typing.Literal`)\[\'h\', \'m\', \'s\', \'ms\', \'us\', \'ns\'\] | The unit to truncate to | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|-----------------------------------------------------------------|----------------------------| +| | [TimeValue](`letsql.vendor.ibis.expr.types.temporal.TimeValue`) | `self` truncated to `unit` | + +# DateValue { #letsql.vendor.ibis.expr.types.temporal.DateValue } + +```python +DateValue(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [day](#letsql.vendor.ibis.expr.types.temporal.DateValue.day) | Extract the day component. | +| [day_of_year](#letsql.vendor.ibis.expr.types.temporal.DateValue.day_of_year) | Extract the day of the year component. | +| [epoch_seconds](#letsql.vendor.ibis.expr.types.temporal.DateValue.epoch_seconds) | Extract UNIX epoch in seconds. | +| [month](#letsql.vendor.ibis.expr.types.temporal.DateValue.month) | Extract the month component. | +| [quarter](#letsql.vendor.ibis.expr.types.temporal.DateValue.quarter) | Extract the quarter component. | +| [truncate](#letsql.vendor.ibis.expr.types.temporal.DateValue.truncate) | Truncate date expression to units of `unit`. | +| [week_of_year](#letsql.vendor.ibis.expr.types.temporal.DateValue.week_of_year) | Extract the week of the year component. | +| [year](#letsql.vendor.ibis.expr.types.temporal.DateValue.year) | Extract the year component. | + +### day { #letsql.vendor.ibis.expr.types.temporal.DateValue.day } + +```python +day() +``` + +Extract the day component. + +### day_of_year { #letsql.vendor.ibis.expr.types.temporal.DateValue.day_of_year } + +```python +day_of_year() +``` + +Extract the day of the year component. + +### epoch_seconds { #letsql.vendor.ibis.expr.types.temporal.DateValue.epoch_seconds } + +```python +epoch_seconds() +``` + +Extract UNIX epoch in seconds. + +### month { #letsql.vendor.ibis.expr.types.temporal.DateValue.month } + +```python +month() +``` + +Extract the month component. + +### quarter { #letsql.vendor.ibis.expr.types.temporal.DateValue.quarter } + +```python +quarter() +``` + +Extract the quarter component. + +### truncate { #letsql.vendor.ibis.expr.types.temporal.DateValue.truncate } + +```python +truncate(unit) +``` + +Truncate date expression to units of `unit`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------|---------------------------|------------| +| unit | [Literal](`typing.Literal`)\[\'Y\', \'Q\', \'M\', \'W\', \'D\'\] | Unit to truncate `arg` to | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|-----------------------------------------------------------------|---------------------------------| +| | [DateValue](`letsql.vendor.ibis.expr.types.temporal.DateValue`) | Truncated date value expression | + +### week_of_year { #letsql.vendor.ibis.expr.types.temporal.DateValue.week_of_year } + +```python +week_of_year() +``` + +Extract the week of the year component. + +### year { #letsql.vendor.ibis.expr.types.temporal.DateValue.year } + +```python +year() +``` + +Extract the year component. + +# DayOfWeek { #letsql.vendor.ibis.expr.types.temporal.DayOfWeek } + +```python +DayOfWeek(self, expr) +``` + +A namespace of methods for extracting day of week information. + +## Methods + +| Name | Description | +| --- | --- | +| [full_name](#letsql.vendor.ibis.expr.types.temporal.DayOfWeek.full_name) | Get the name of the day of the week. | +| [index](#letsql.vendor.ibis.expr.types.temporal.DayOfWeek.index) | Get the index of the day of the week. | + +### full_name { #letsql.vendor.ibis.expr.types.temporal.DayOfWeek.full_name } + +```python +full_name() +``` + +Get the name of the day of the week. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------|---------------------------------| +| | [StringValue](`letsql.vendor.ibis.expr.types.strings.StringValue`) | The name of the day of the week | + +### index { #letsql.vendor.ibis.expr.types.temporal.DayOfWeek.index } + +```python +index() +``` + +Get the index of the day of the week. + +::: {.callout-note} +## Ibis follows the `pandas` convention for day numbering: Monday = 0 and Sunday = 6. +::: + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------|-----------------------------------| +| | [IntegerValue](`letsql.vendor.ibis.expr.types.numeric.IntegerValue`) | The index of the day of the week. | + +# TimestampValue { #letsql.vendor.ibis.expr.types.temporal.TimestampValue } + +```python +TimestampValue(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [date](#letsql.vendor.ibis.expr.types.temporal.TimestampValue.date) | Return the date component of the expression. | +| [truncate](#letsql.vendor.ibis.expr.types.temporal.TimestampValue.truncate) | Truncate timestamp expression to units of `unit`. | + +### date { #letsql.vendor.ibis.expr.types.temporal.TimestampValue.date } + +```python +date() +``` + +Return the date component of the expression. + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|-----------------------------------------------------------------|------------------------------| +| | [DateValue](`letsql.vendor.ibis.expr.types.temporal.DateValue`) | The date component of `self` | + +### truncate { #letsql.vendor.ibis.expr.types.temporal.TimestampValue.truncate } + +```python +truncate(unit) +``` + +Truncate timestamp expression to units of `unit`. + +#### Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|---------------------------------------------------------------------------------------------------------------|---------------------|------------| +| unit | [Literal](`typing.Literal`)\[\'Y\', \'Q\', \'M\', \'W\', \'D\', \'h\', \'m\', \'s\', \'ms\', \'us\', \'ns\'\] | Unit to truncate to | _required_ | + +#### Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|---------------------------------------------------------------------------|--------------------------------| +| | [TimestampValue](`letsql.vendor.ibis.expr.types.temporal.TimestampValue`) | Truncated timestamp expression | + +# IntervalValue { #letsql.vendor.ibis.expr.types.temporal.IntervalValue } + +```python +IntervalValue(self, arg) +``` + + + +## Methods + +| Name | Description | +| --- | --- | +| [to_unit](#letsql.vendor.ibis.expr.types.temporal.IntervalValue.to_unit) | | + +### to_unit { #letsql.vendor.ibis.expr.types.temporal.IntervalValue.to_unit } + +```python +to_unit(target_unit) +``` + diff --git a/docs/reference/index.qmd b/docs/reference/index.qmd new file mode 100644 index 00000000..17ea2e36 --- /dev/null +++ b/docs/reference/index.qmd @@ -0,0 +1,15 @@ +# Reference {.doc .doc-index} + +## Expression API + +APIs for manipulating table, column and scalar expressions + +| | | +| --- | --- | +| [Table expressions](expression-relations.qmd) | Tables are one of the core data structures in Ibis. | +| [Generic expressions](expression-generic.qmd) | Scalars and columns of any element type. | +| [Numeric and Boolean expressions](expression-numeric.qmd) | Integer, floating point, decimal, and boolean expressions. | +| [String expressions](expression-strings.qmd) | All string operations are valid for both scalars and columns. | +| [Temporal expressions](expression-temporal.qmd) | Dates, times, timestamps and intervals. | +| [Top Level API functions](toplevel-api.qmd) | | +| [ML API functions](ml-api.qmd) | | \ No newline at end of file diff --git a/docs/reference/ml-api.qmd b/docs/reference/ml-api.qmd new file mode 100644 index 00000000..d29466fe --- /dev/null +++ b/docs/reference/ml-api.qmd @@ -0,0 +1,61 @@ +# ML API functions + + + +# train_test_splits { #letsql.expr.ml.train_test_splits } + +```python +train_test_splits( + table, + unique_key, + test_sizes, + num_buckets=10000, + random_seed=None, +) +``` + +Generates multiple train/test splits of an Ibis table for different test sizes. + +This function splits an Ibis table into multiple subsets based on a unique key +or combination of keys and a list of test sizes. It uses a hashing function to +convert the unique key into an integer, then applies a modulo operation to split +the data into buckets. Each subset of data is defined by a range of +buckets determined by the cumulative sum of the test sizes. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|-------------|--------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------| +| table | [ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`) | The input Ibis table to be split. | _required_ | +| unique_key | [str](`str`) \| [list](`list`)\[[str](`str`)\] | The column name(s) that uniquely identify each row in the table. This unique_key is used to create a deterministic split of the dataset through a hashing process. | _required_ | +| test_sizes | [Iterable](`typing.Iterable`)\[[float](`float`)\] \| [float](`float`) | An iterable of floats representing the desired proportions for data splits. Each value should be between 0 and 1, and their sum must equal 1. The order of test sizes determines the order of the generated subsets. If float is passed it assumes that the value is for the test size and that a tradition tain test split of (1-test_size, test_size) is returned. | _required_ | +| num_buckets | [int](`int`) | The number of buckets into which the data can be binned after being hashed (default is 10000). It controls how finely the data is divided during the split process. Adjusting num_buckets can affect the granularity and efficiency of the splitting operation, balancing between accuracy and computational efficiency. | `10000` | +| random_seed | [int](`int`) \| None | Seed for the random number generator. If provided, ensures reproducibility of the split (default is None). | `None` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|-----------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------| +| | [Iterator](`typing.Iterator`)\[[ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`)\] | An iterator yielding Ibis table expressions, each representing a mutually exclusive subset of the original table based on the specified test sizes. | + +## Raises {.doc-section .doc-section-raises} + +| Name | Type | Description | +|--------|----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------| +| | [ValueError](`ValueError`) | If any value in `test_sizes` is not between 0 and 1. If `test_sizes` does not sum to 1. If `num_buckets` is not an integer greater than 1. | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql as ls +>>> table = ls.memtable({"key": range(100), "value": range(100,200)}) +>>> unique_key = "key" +>>> test_sizes = [0.2, 0.3, 0.5] +>>> splits = ls.train_test_splits(table, unique_key, test_sizes, num_buckets=10, random_seed=42) +>>> for i, split_table in enumerate(splits): +... print(f"Split {i+1} size: {split_table.count().execute()}") +... print(split_table.execute()) +Split 1 size: 20 +Split 2 size: 30 +Split 3 size: 50 +``` \ No newline at end of file diff --git a/docs/reference/toplevel-api.qmd b/docs/reference/toplevel-api.qmd new file mode 100644 index 00000000..a56bf544 --- /dev/null +++ b/docs/reference/toplevel-api.qmd @@ -0,0 +1,1509 @@ +# Top Level API functions + + + +# param { #letsql.expr.api.param } + +```python +param(type) +``` + +Create a deferred parameter of a given type. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|---------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------|------------| +| type | [Union](`typing.Union`)\[[dt](`letsql.vendor.ibis.expr.datatypes`).[DataType](`letsql.vendor.ibis.expr.datatypes.DataType`), [str](`str`)\] | The type of the unbound parameter, e.g., double, int64, date, etc. | _required_ | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------|--------------------------------------------| +| | [Scalar](`letsql.vendor.ibis.expr.types.Scalar`) | A scalar expression backend by a parameter | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> from datetime import date +>>> import letsql +>>> start = letsql.param("date") +>>> t = letsql.memtable( +... { +... "date_col": [date(2013, 1, 1), date(2013, 1, 2), date(2013, 1, 3)], +... "value": [1.0, 2.0, 3.0], +... }, +... ) +>>> expr = t.filter(t.date_col >= start).value.sum() +>>> expr.execute(params={start: date(2013, 1, 1)}) +6.0 +>>> expr.execute(params={start: date(2013, 1, 2)}) +5.0 +>>> expr.execute(params={start: date(2013, 1, 3)}) +3.0 +``` + +# schema { #letsql.expr.api.schema } + +```python +schema(pairs=None, names=None, types=None) +``` + +Validate and return a [`Schema`](./schemas.qmd#ibis.expr.schema.Schema) object. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------|-----------| +| pairs | [SchemaLike](`letsql.vendor.ibis.expr.schema.SchemaLike`) \| None | List or dictionary of name, type pairs. Mutually exclusive with `names` and `types` arguments. | `None` | +| names | [Iterable](`collections.abc.Iterable`)\[[str](`str`)\] \| None | Field names. Mutually exclusive with `pairs`. | `None` | +| types | [Iterable](`collections.abc.Iterable`)\[[str](`str`) \| [dt](`letsql.vendor.ibis.expr.datatypes`).[DataType](`letsql.vendor.ibis.expr.datatypes.DataType`)\] \| None | Field types. Mutually exclusive with `pairs`. | `None` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|---------------------------------------------------|----------------| +| | [Schema](`letsql.vendor.ibis.expr.schema.Schema`) | An ibis schema | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> from letsql import schema +>>> sc = schema([("foo", "string"), ("bar", "int64"), ("baz", "boolean")]) +>>> sc = schema(names=["foo", "bar", "baz"], types=["string", "int64", "boolean"]) +>>> sc = schema(dict(foo="string")) # no-op +``` + +# table { #letsql.expr.api.table } + +```python +table(schema=None, name=None, catalog=None, database=None) +``` + +Create a table literal or an abstract table without data. + +Ibis uses the word database to refer to a collection of tables, and the word +catalog to refer to a collection of databases. You can use a combination of +`catalog` and `database` to specify a hierarchical location for table. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|-------------------------------------------------------------------|---------------------------------------------------------------|-----------| +| schema | [SchemaLike](`letsql.vendor.ibis.expr.schema.SchemaLike`) \| None | A schema for the table | `None` | +| name | [str](`str`) \| None | Name for the table. One is generated if this value is `None`. | `None` | +| catalog | [str](`str`) \| None | A collection of database. | `None` | +| database | [str](`str`) \| None | A collection of tables. Required if catalog is not `None`. | `None` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------|--------------------| +| | [Table](`letsql.vendor.ibis.expr.types.Table`) | A table expression | + +## Examples {.doc-section .doc-section-examples} + +Create a table with no data backing it + +```python +>>> import letsql +>>> letsql.options.interactive = False +>>> t = letsql.table(schema=dict(a="int", b="string"), name="t") +>>> t +UnboundTable: t + a int64 + b string +``` + + +Create a table with no data backing it in a specific location + +```python +>>> import letsql +>>> letsql.options.interactive = False +>>> t = letsql.table(schema=dict(a="int"), name="t", catalog="cat", database="db") +>>> t +UnboundTable: cat.db.t + a int64 +``` + +# memtable { #letsql.expr.api.memtable } + +```python +memtable(data, *, columns=None, schema=None, name=None) +``` + +Construct an ibis table expression from in-memory data. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------|-------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------| +| data | | A table-like object (`pandas.DataFrame`, `pyarrow.Table`, or `polars.DataFrame`), or any data accepted by the `pandas.DataFrame` constructor (e.g. a list of dicts). Note that ibis objects (e.g. `MapValue`) may not be passed in as part of `data` and will result in an error. Do not depend on the underlying storage type (e.g., pyarrow.Table), it's subject to change across non-major releases. | _required_ | +| columns | [Iterable](`collections.abc.Iterable`)\[[str](`str`)\] \| None | Optional [](`typing.Iterable`) of [](`str`) column names. If provided, must match the number of columns in `data`. | `None` | +| schema | [SchemaLike](`letsql.vendor.ibis.expr.schema.SchemaLike`) \| None | Optional [`Schema`](./schemas.qmd#ibis.expr.schema.Schema). The functions use `data` to infer a schema if not passed. | `None` | +| name | [str](`str`) \| None | Optional name of the table. | `None` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------|----------------------------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.Table`) | A table expression backed by in-memory data. | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = False +>>> t = letsql.memtable([{"a": 1}, {"a": 2}]) +>>> t +InMemoryTable + data: + PandasDataFrameProxy: + a + 0 1 + 1 2 +``` + +```python +>>> t = letsql.memtable([{"a": 1, "b": "foo"}, {"a": 2, "b": "baz"}]) +>>> t +InMemoryTable + data: + PandasDataFrameProxy: + a b + 0 1 foo + 1 2 baz +``` + +Create a table literal without column names embedded in the data and pass +`columns` + +```python +>>> t = letsql.memtable([(1, "foo"), (2, "baz")], columns=["a", "b"]) +>>> t +InMemoryTable + data: + PandasDataFrameProxy: + a b + 0 1 foo + 1 2 baz +``` + +Create a table literal without column names embedded in the data. Ibis +generates column names if none are provided. + +```python +>>> t = letsql.memtable([(1, "foo"), (2, "baz")]) +>>> t +InMemoryTable + data: + PandasDataFrameProxy: + col0 col1 + 0 1 foo + 1 2 baz +``` + +# desc { #letsql.expr.api.desc } + +```python +desc(expr) +``` + +Create a descending sort key from `expr` or column name. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------------------------------------------------------|--------------------------------------------------|------------| +| expr | [ir](`letsql.vendor.ibis.expr.types`).[Column](`letsql.vendor.ibis.expr.types.Column`) \| [str](`str`) | The expression or column name to use for sorting | _required_ | + +## See Also {.doc-section .doc-section-see-also} + +[`Value.desc()`](./expression-generic.qmd#ibis.expr.types.generic.Value.desc) + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.examples.penguins.fetch() +>>> t[["species", "year"]].order_by(letsql.desc("year")).head() +┏━━━━━━━━━┳━━━━━━━┓ +┃ species ┃ year ┃ +┡━━━━━━━━━╇━━━━━━━┩ +│ string │ int64 │ +├─────────┼───────┤ +│ Adelie │ 2009 │ +│ Adelie │ 2009 │ +│ Adelie │ 2009 │ +│ Adelie │ 2009 │ +│ Adelie │ 2009 │ +└─────────┴───────┘ +``` + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------------------------------|---------------| +| | [ir](`letsql.vendor.ibis.expr.types`).[ValueExpr](`letsql.vendor.ibis.expr.types.ValueExpr`) | An expression | + +# asc { #letsql.expr.api.asc } + +```python +asc(expr) +``` + +Create an ascending sort key from `asc` or column name. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------------------------------------------------------------------------------------------------------|--------------------------------------------------|------------| +| expr | [ir](`letsql.vendor.ibis.expr.types`).[Column](`letsql.vendor.ibis.expr.types.Column`) \| [str](`str`) | The expression or column name to use for sorting | _required_ | + +## See Also {.doc-section .doc-section-see-also} + +[`Value.asc()`](./expression-generic.qmd#ibis.expr.types.generic.Value.asc) + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.examples.penguins.fetch() +>>> t[["species", "year"]].order_by(letsql.asc("year")).head() +┏━━━━━━━━━┳━━━━━━━┓ +┃ species ┃ year ┃ +┡━━━━━━━━━╇━━━━━━━┩ +│ string │ int64 │ +├─────────┼───────┤ +│ Adelie │ 2007 │ +│ Adelie │ 2007 │ +│ Adelie │ 2007 │ +│ Adelie │ 2007 │ +│ Adelie │ 2007 │ +└─────────┴───────┘ +``` + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------------------------------------------------------|---------------| +| | [ir](`letsql.vendor.ibis.expr.types`).[ValueExpr](`letsql.vendor.ibis.expr.types.ValueExpr`) | An expression | + +# preceding { #letsql.expr.api.preceding } + +```python +preceding(value) +``` + + + +# following { #letsql.expr.api.following } + +```python +following(value) +``` + + + +# and_ { #letsql.expr.api.and_ } + +```python +and_(*predicates) +``` + +Combine multiple predicates using `&`. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|------------|----------------------------------------------------------------------------------------------------|---------------------------|-----------| +| predicates | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) | Boolean value expressions | `()` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------|----------------------------------------------------------------------------------------------------------------------------| +| | [BooleanValue](`BooleanValue`) | A new predicate that evaluates to True if all composing predicates are True. If no predicates were provided, returns True. | + +# or_ { #letsql.expr.api.or_ } + +```python +or_(*predicates) +``` + +Combine multiple predicates using `|`. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|------------|----------------------------------------------------------------------------------------------------|---------------------------|-----------| +| predicates | [ir](`letsql.vendor.ibis.expr.types`).[BooleanValue](`letsql.vendor.ibis.expr.types.BooleanValue`) | Boolean value expressions | `()` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------|-----------------------------------------------------------------------------------------------------------------------------| +| | [BooleanValue](`BooleanValue`) | A new predicate that evaluates to True if any composing predicates are True. If no predicates were provided, returns False. | + +# random { #letsql.expr.api.random } + +```python +random() +``` + +Return a random floating point number in the range [0.0, 1.0). + +Similar to [](`random.random`) in the Python standard library. + +::: {.callout-note} +## Repeated use of `random` + +`ibis.random()` will generate a column of distinct random numbers even if +the same instance of `ibis.random()` is reused. + +When Ibis compiles an expression to SQL, each place where `random` is used +will render as a separate call to the given backend's random number +generator. + +>>> import letsql +>>> r_a = letsql.random() # doctest: +SKIP + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------|-------------------------------| +| | [FloatingScalar](`FloatingScalar`) | Random float value expression | + +# uuid { #letsql.expr.api.uuid } + +```python +uuid() +``` + +Return a random UUID version 4 value. + +Similar to [('uuid.uuid4`) in the Python standard library. + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> letsql.uuid() +UUID('e57e927b-aed2-483b-9140-dc32a26cad95') +``` + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------|------------------------------| +| | [UUIDScalar](`UUIDScalar`) | Random UUID value expression | + +# case { #letsql.expr.api.case } + +```python +case() +``` + +Begin constructing a case expression. + +Use the `.when` method on the resulting object followed by `.end` to create a +complete case expression. + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------------------|-------------------------------------------------------------| +| | [SearchedCaseBuilder](`SearchedCaseBuilder`) | A builder object to use for constructing a case expression. | + +## See Also {.doc-section .doc-section-see-also} + +[`Value.case()`](./expression-generic.qmd#ibis.expr.types.generic.Value.case) + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> from letsql.vendor.ibis import _ +>>> letsql.options.interactive = True +>>> t = letsql.memtable( +... { +... "left": [1, 2, 3, 4], +... "symbol": ["+", "-", "*", "/"], +... "right": [5, 6, 7, 8], +... } +... ) +>>> t.mutate( +... result=( +... letsql.case() +... .when(_.symbol == "+", _.left + _.right) +... .when(_.symbol == "-", _.left - _.right) +... .when(_.symbol == "*", _.left * _.right) +... .when(_.symbol == "/", _.left / _.right) +... .end() +... ) +... ) +┏━━━━━━━┳━━━━━━━━┳━━━━━━━┳━━━━━━━━━┓ +┃ left ┃ symbol ┃ right ┃ result ┃ +┡━━━━━━━╇━━━━━━━━╇━━━━━━━╇━━━━━━━━━┩ +│ int64 │ string │ int64 │ float64 │ +├───────┼────────┼───────┼─────────┤ +│ 1 │ + │ 5 │ 6.0 │ +│ 2 │ - │ 6 │ -4.0 │ +│ 3 │ * │ 7 │ 21.0 │ +│ 4 │ / │ 8 │ 0.5 │ +└───────┴────────┴───────┴─────────┘ +``` + +# now { #letsql.expr.api.now } + +```python +now() +``` + +Return an expression that will compute the current timestamp. + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------|---------------------------------------------------| +| | [TimestampScalar](`TimestampScalar`) | An expression representing the current timestamp. | + +# today { #letsql.expr.api.today } + +```python +today() +``` + +Return an expression that will compute the current date. + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------|----------------------------------------------| +| | [DateScalar](`DateScalar`) | An expression representing the current date. | + +# rank { #letsql.expr.api.rank } + +```python +rank() +``` + +Compute position of first element within each equal-value group in sorted order. + +Equivalent to SQL's `RANK()` window function. + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------|---------------| +| | [Int64Column](`Int64Column`) | The min rank | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(rank=letsql.rank().over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━┓ +┃ values ┃ rank ┃ +┡━━━━━━━━╇━━━━━━━┩ +│ int64 │ int64 │ +├────────┼───────┤ +│ 1 │ 0 │ +│ 1 │ 0 │ +│ 2 │ 2 │ +│ 2 │ 2 │ +│ 2 │ 2 │ +│ 3 │ 5 │ +└────────┴───────┘ +``` + +# dense_rank { #letsql.expr.api.dense_rank } + +```python +dense_rank() +``` + +Position of first element within each group of equal values. + +Values are returned in sorted order and duplicate values are ignored. + +Equivalent to SQL's `DENSE_RANK()`. + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------|---------------| +| | [IntegerColumn](`IntegerColumn`) | The rank | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(rank=letsql.dense_rank().over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━┓ +┃ values ┃ rank ┃ +┡━━━━━━━━╇━━━━━━━┩ +│ int64 │ int64 │ +├────────┼───────┤ +│ 1 │ 0 │ +│ 1 │ 0 │ +│ 2 │ 1 │ +│ 2 │ 1 │ +│ 2 │ 1 │ +│ 3 │ 2 │ +└────────┴───────┘ +``` + +# percent_rank { #letsql.expr.api.percent_rank } + +```python +percent_rank() +``` + +Return the relative rank of the values in the column. + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------|------------------| +| | [FloatingColumn](`FloatingColumn`) | The percent rank | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(pct_rank=letsql.percent_rank().over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━━━━┓ +┃ values ┃ pct_rank ┃ +┡━━━━━━━━╇━━━━━━━━━━┩ +│ int64 │ float64 │ +├────────┼──────────┤ +│ 1 │ 0.0 │ +│ 1 │ 0.0 │ +│ 2 │ 0.4 │ +│ 2 │ 0.4 │ +│ 2 │ 0.4 │ +│ 3 │ 1.0 │ +└────────┴──────────┘ +``` + +# cume_dist { #letsql.expr.api.cume_dist } + +```python +cume_dist() +``` + +Return the cumulative distribution over a window. + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------|-----------------------------| +| | [FloatingColumn](`FloatingColumn`) | The cumulative distribution | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(dist=letsql.cume_dist().over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━━━━┓ +┃ values ┃ dist ┃ +┡━━━━━━━━╇━━━━━━━━━━┩ +│ int64 │ float64 │ +├────────┼──────────┤ +│ 1 │ 0.333333 │ +│ 1 │ 0.333333 │ +│ 2 │ 0.833333 │ +│ 2 │ 0.833333 │ +│ 2 │ 0.833333 │ +│ 3 │ 1.000000 │ +└────────┴──────────┘ +``` + +# ntile { #letsql.expr.api.ntile } + +```python +ntile(buckets) +``` + +Return the integer number of a partitioning of the column values. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------|--------------------------------------------------------------------------------------------------------------------|-------------------------------------|------------| +| buckets | [int](`int`) \| [ir](`letsql.vendor.ibis.expr.types`).[IntegerValue](`letsql.vendor.ibis.expr.types.IntegerValue`) | Number of buckets to partition into | _required_ | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(ntile=letsql.ntile(2).over(order_by=t.values)) +┏━━━━━━━━┳━━━━━━━┓ +┃ values ┃ ntile ┃ +┡━━━━━━━━╇━━━━━━━┩ +│ int64 │ int64 │ +├────────┼───────┤ +│ 1 │ 0 │ +│ 1 │ 0 │ +│ 2 │ 0 │ +│ 2 │ 1 │ +│ 2 │ 1 │ +│ 3 │ 1 │ +└────────┴───────┘ +``` + +# row_number { #letsql.expr.api.row_number } + +```python +row_number() +``` + +Return an analytic function expression for the current row number. + +::: {.callout-note} +`row_number` is normalized across backends to start at 0 +::: + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------------|--------------------------------------| +| | [IntegerColumn](`IntegerColumn`) | A column expression enumerating rows | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"values": [1, 2, 1, 2, 3, 2]}) +>>> t.mutate(rownum=letsql.row_number()) +┏━━━━━━━━┳━━━━━━━━┓ +┃ values ┃ rownum ┃ +┡━━━━━━━━╇━━━━━━━━┩ +│ int64 │ int64 │ +├────────┼────────┤ +│ 1 │ 0 │ +│ 2 │ 1 │ +│ 1 │ 2 │ +│ 2 │ 3 │ +│ 3 │ 4 │ +│ 2 │ 5 │ +└────────┴────────┘ +``` + +# read_csv { #letsql.expr.api.read_csv } + +```python +read_csv(sources, table_name=None, **kwargs) +``` + +Lazily load a CSV or set of CSVs. + +This function delegates to the `read_csv` method on the current default +backend (DuckDB or `ibis.config.default_backend`). + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|------------|----------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------| +| sources | [str](`str`) \| [Path](`pathlib.Path`) \| [Sequence](`collections.abc.Sequence`)\[[str](`str`) \| [Path](`pathlib.Path`)\] | A filesystem path or URL or list of same. Supports CSV and TSV files. | _required_ | +| table_name | [str](`str`) \| None | A name to refer to the table. If not provided, a name will be generated. | `None` | +| kwargs | [Any](`typing.Any`) | Backend-specific keyword arguments for the file type. For the DuckDB backend used by default, please refer to: * CSV/TSV: https://duckdb.org/docs/data/csv/overview.html#parameters. | `{}` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------------------------|--------------------------------------| +| | [ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`) | Table expression representing a file | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> lines = '''a,b +... 1,d +... 2, +... ,f +... ''' +>>> with open("/tmp/lines.csv", mode="w") as f: +... nbytes = f.write(lines) # nbytes is unused +>>> t = letsql.read_csv("/tmp/lines.csv") +>>> t +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ d │ +│ 2 │ NULL │ +│ NULL │ f │ +└───────┴────────┘ +``` + +# read_parquet { #letsql.expr.api.read_parquet } + +```python +read_parquet(sources, table_name=None, **kwargs) +``` + +Lazily load a parquet file or set of parquet files. + +This function delegates to the `read_parquet` method on the current default +backend (DuckDB or `ibis.config.default_backend`). + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|------------|----------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|------------| +| sources | [str](`str`) \| [Path](`pathlib.Path`) \| [Sequence](`collections.abc.Sequence`)\[[str](`str`) \| [Path](`pathlib.Path`)\] | A filesystem path or URL or list of same. | _required_ | +| table_name | [str](`str`) \| None | A name to refer to the table. If not provided, a name will be generated. | `None` | +| kwargs | [Any](`typing.Any`) | Backend-specific keyword arguments for the file type. For the DuckDB backend used by default, please refer to: * Parquet: https://duckdb.org/docs/data/parquet | `{}` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------------------------|--------------------------------------| +| | [ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`) | Table expression representing a file | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> import pandas as pd +>>> letsql.options.interactive = True +>>> df = pd.DataFrame({"a": [1, 2, 3], "b": list("ghi")}) +>>> df + a b +0 1 g +1 2 h +2 3 i +>>> df.to_parquet("/tmp/data.parquet") +>>> t = letsql.read_parquet("/tmp/data.parquet") +>>> t +┏━━━━━━━┳━━━━━━━━┓ +┃ a ┃ b ┃ +┡━━━━━━━╇━━━━━━━━┩ +│ int64 │ string │ +├───────┼────────┤ +│ 1 │ g │ +│ 2 │ h │ +│ 3 │ i │ +└───────┴────────┘ +``` + +# register { #letsql.expr.api.register } + +```python +register(source, table_name=None, **kwargs) +``` + + + +# read_postgres { #letsql.expr.api.read_postgres } + +```python +read_postgres(uri, table_name=None, **kwargs) +``` + + + +# read_sqlite { #letsql.expr.api.read_sqlite } + +```python +read_sqlite(path, *, table_name=None) +``` + + + +# union { #letsql.expr.api.union } + +```python +union(table, *rest, distinct=False) +``` + +Compute the set union of multiple table expressions. + +The input tables must have identical schemas. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|--------------------------------------------------------------------------------------|------------------------------|------------| +| table | [ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`) | A table expression | _required_ | +| *rest | [ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`) | Additional table expressions | `()` | +| distinct | [bool](`bool`) | Only return distinct rows | `False` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------|-------------------------------------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.Table`) | A new table containing the union of all input tables. | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t1 = letsql.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = letsql.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> letsql.union(t1, t2) # union all by default +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +│ 2 │ +│ 3 │ +└───────┘ +>>> letsql.union(t1, t2, distinct=True).order_by("a") +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +│ 3 │ +└───────┘ +``` + +# intersect { #letsql.expr.api.intersect } + +```python +intersect(table, *rest, distinct=True) +``` + +Compute the set intersection of multiple table expressions. + +The input tables must have identical schemas. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|--------------------------------------------------------------------------------------|------------------------------|------------| +| table | [ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`) | A table expression | _required_ | +| *rest | [ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`) | Additional table expressions | `()` | +| distinct | [bool](`bool`) | Only return distinct rows | `True` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------|--------------------------------------------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.Table`) | A new table containing the intersection of all input tables. | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t1 = letsql.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = letsql.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> letsql.intersect(t1, t2) +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +└───────┘ +``` + +# difference { #letsql.expr.api.difference } + +```python +difference(table, *rest, distinct=True) +``` + +Compute the set difference of multiple table expressions. + +The input tables must have identical schemas. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|----------|--------------------------------------------------------------------------------------|------------------------------------------------------------|------------| +| table | [ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`) | A table expression | _required_ | +| *rest | [ir](`letsql.vendor.ibis.expr.types`).[Table](`letsql.vendor.ibis.expr.types.Table`) | Additional table expressions | `()` | +| distinct | [bool](`bool`) | Only diff distinct rows not occurring in the calling table | `True` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------|--------------------------------------------------------------| +| | [Table](`letsql.vendor.ibis.expr.types.Table`) | The rows present in `self` that are not present in `tables`. | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t1 = letsql.memtable({"a": [1, 2]}) +>>> t1 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +│ 2 │ +└───────┘ +>>> t2 = letsql.memtable({"a": [2, 3]}) +>>> t2 +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 2 │ +│ 3 │ +└───────┘ +>>> letsql.difference(t1, t2) +┏━━━━━━━┓ +┃ a ┃ +┡━━━━━━━┩ +│ int64 │ +├───────┤ +│ 1 │ +└───────┘ +``` + +# ifelse { #letsql.expr.api.ifelse } + +```python +ifelse(condition, true_expr, false_expr) +``` + +Construct a ternary conditional expression. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|------------|---------------------|--------------------------------------------------------------------|------------| +| condition | [Any](`typing.Any`) | A boolean expression | _required_ | +| true_expr | [Any](`typing.Any`) | Expression to return if `condition` evaluates to `True` | _required_ | +| false_expr | [Any](`typing.Any`) | Expression to return if `condition` evaluates to `False` or `NULL` | _required_ | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------------------------------------|---------------------------------------------------------------------| +| Value | [ir](`letsql.vendor.ibis.expr.types`).[Value](`letsql.vendor.ibis.expr.types.Value`) | The value of `true_expr` if `condition` is `True` else `false_expr` | + +## See Also {.doc-section .doc-section-see-also} + +[`BooleanValue.ifelse()`](./expression-numeric.qmd#ibis.expr.types.logical.BooleanValue.ifelse) + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> t = letsql.memtable({"condition": [True, False, True, None]}) +>>> letsql.ifelse(t.condition, "yes", "no") +┏━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓ +┃ IfElse(condition, 'yes', 'no') ┃ +┡━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩ +│ string │ +├────────────────────────────────┤ +│ yes │ +│ no │ +│ yes │ +│ no │ +└────────────────────────────────┘ +``` + +# coalesce { #letsql.expr.api.coalesce } + +```python +coalesce(*args) +``` + +Return the first non-null value from `args`. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|---------------------|---------------------------------------------------------|-----------| +| args | [Any](`typing.Any`) | Arguments from which to choose the first non-null value | `()` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------|----------------------| +| | [Value](`letsql.vendor.ibis.expr.types.Value`) | Coalesced expression | + +## See Also {.doc-section .doc-section-see-also} + +[`Value.coalesce()`](#ibis.expr.types.generic.Value.coalesce) +[`Value.fill_null()`](#ibis.expr.types.generic.Value.fill_null) + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> letsql.coalesce(None, 4, 5) +4 +``` + +# greatest { #letsql.expr.api.greatest } + +```python +greatest(*args) +``` + +Compute the largest value among the supplied arguments. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|---------------------|--------------------------|-----------| +| args | [Any](`typing.Any`) | Arguments to choose from | `()` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------|---------------------------------| +| | [Value](`letsql.vendor.ibis.expr.types.Value`) | Maximum of the passed arguments | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> letsql.greatest(None, 4, 5) +5 +``` + +# least { #letsql.expr.api.least } + +```python +least(*args) +``` + +Compute the smallest value among the supplied arguments. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|---------------------|--------------------------|-----------| +| args | [Any](`typing.Any`) | Arguments to choose from | `()` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------|---------------------------------| +| | [Value](`letsql.vendor.ibis.expr.types.Value`) | Minimum of the passed arguments | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +>>> letsql.least(None, 4, 5) +4 +``` + +# range { #letsql.expr.api.range } + +```python +range(start, stop, step) +``` + +Generate a range of values. + +Integer ranges are supported, as well as timestamp ranges. + +::: {.callout-note} +`start` is inclucive and `stop` is exclusive, just like Python's builtin +[`range`](range). + +When `step` equals 0, however, this function will return an empty array. + +Python's `range` will raise an exception when `step` is zero. +::: + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|--------|--------------------------------------|------------| +| start | | Lower bound of the range, inclusive. | _required_ | +| stop | | Upper bound of the range, exclusive. | _required_ | +| step | | Step value. Optional, defaults to 1. | _required_ | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|----------------------------|--------------------| +| | [ArrayValue](`ArrayValue`) | An array of values | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +``` + +Range using only a stop argument + +```python +>>> letsql.range(5) +[0, 1, ... +3] +``` + +Simple range using start and stop + +```python +>>> letsql.range(1, 5) +[1, 2, ... +2] +``` + + +Generate an empty range + +```python +>>> letsql.range(0) +[] +``` + +Negative step values are supported + +```python +>>> letsql.range(10, 4, -2) +[10, 8, ... +1] +``` + + +`ibis.range` behaves the same as Python's range ... + +```python +>>> letsql.range(0, 7, -1) +[] +``` + +... except when the step is zero, in which case `ibis.range` returns an +empty array + +```python +>>> letsql.range(0, 5, 0) +[] +``` + +Because the resulting expression is array, you can unnest the values + +```python +>>> letsql.range(5).unnest().name("numbers") +┏━━━━━━━━━┓ +┃ numbers ┃ +┡━━━━━━━━━┩ +│ int8 │ +├─────────┤ +│ 0 │ +│ 1 │ +│ 2 │ +│ 3 │ +│ 4 │ +└─────────┘ +``` + +# timestamp { #letsql.expr.api.timestamp } + +```python +timestamp( + value_or_year, + month=None, + day=None, + hour=None, + minute=None, + second=None, + /, + timezone=None, +) +``` + +Construct a timestamp scalar or column. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------------|--------|----------------------------------------------------------------------------------------------------------------------------------------|------------| +| value_or_year | | Either a string value or `datetime.datetime` to coerce to a timestamp, or an integral value representing the timestamp year component. | _required_ | +| month | | The timestamp month component; required if `value_or_year` is a year. | `None` | +| day | | The timestamp day component; required if `value_or_year` is a year. | `None` | +| hour | | The timestamp hour component; required if `value_or_year` is a year. | `None` | +| minute | | The timestamp minute component; required if `value_or_year` is a year. | `None` | +| second | | The timestamp second component; required if `value_or_year` is a year. | `None` | +| timezone | | The timezone name, or none for a timezone-naive timestamp. | `None` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------------------------------------|------------------------| +| | [TimestampValue](`letsql.vendor.ibis.expr.types.TimestampValue`) | A timestamp expression | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +``` + +Create a timestamp scalar from a string + +```python +>>> letsql.timestamp("2023-01-02T03:04:05") +Timestamp('2023-01-02 03:04:05') +``` + + +Create a timestamp scalar from components + +```python +>>> letsql.timestamp(2023, 1, 2, 3, 4, 5) +Timestamp('2023-01-02 03:04:05') +``` + + +Create a timestamp column from components + +```python +>>> t = letsql.memtable({"y": [2001, 2002], "m": [1, 4], "d": [2, 5], "h": [3, 6]}) +>>> letsql.timestamp(t.y, t.m, t.d, t.h, 0, 0).name("timestamp") +┏━━━━━━━━━━━━━━━━━━━━━┓ +┃ timestamp ┃ +┡━━━━━━━━━━━━━━━━━━━━━┩ +│ timestamp │ +├─────────────────────┤ +│ 2001-01-02 03:00:00 │ +│ 2002-04-05 06:00:00 │ +└─────────────────────┘ +``` + +# date { #letsql.expr.api.date } + +```python +date(value_or_year, month=None, day=None, /) +``` + + + +# time { #letsql.expr.api.time } + +```python +time(value_or_hour, minute=None, second=None, /) +``` + +Return a time literal if `value` is coercible to a time. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|---------------|--------|--------------------------------------------------------------------------------------------------------------------------|------------| +| value_or_hour | | Either a string value or `datetime.time` to coerce to a time, or an integral value representing the time hour component. | _required_ | +| minute | | The time minute component; required if `value_or_hour` is an hour. | `None` | +| second | | The time second component; required if `value_or_hour` is an hour. | `None` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------------------------------------------------|-------------------| +| | [TimeValue](`letsql.vendor.ibis.expr.types.TimeValue`) | A time expression | + +## Examples {.doc-section .doc-section-examples} + +```python +>>> import letsql +>>> letsql.options.interactive = True +``` + +Create a time scalar from a string + +```python +>>> letsql.time("01:02:03") +datetime.time(1, 2, 3) +``` + + +Create a time scalar from hour, minute, and second + +```python +>>> letsql.time(1, 2, 3) +datetime.time(1, 2, 3) +``` + + +Create a time column from hour, minute, and second + +```python +>>> t = letsql.memtable({"h": [1, 4], "m": [2, 5], "s": [3, 6]}) +>>> letsql.time(t.h, t.m, t.s).name("time") +┏━━━━━━━━━━┓ +┃ time ┃ +┡━━━━━━━━━━┩ +│ time │ +├──────────┤ +│ 01:02:03 │ +│ 04:05:06 │ +└──────────┘ +``` + +# interval { #letsql.expr.api.interval } + +```python +interval( + value=None, + unit='s', + *, + years=None, + quarters=None, + months=None, + weeks=None, + days=None, + hours=None, + minutes=None, + seconds=None, + milliseconds=None, + microseconds=None, + nanoseconds=None, +) +``` + +Return an interval literal expression. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------------|----------------------------------------------------------------------------------|------------------------|-----------| +| value | [int](`int`) \| [datetime](`datetime`).[timedelta](`datetime.timedelta`) \| None | Interval value. | `None` | +| unit | [str](`str`) | Unit of `value` | `'s'` | +| years | [int](`int`) \| None | Number of years | `None` | +| quarters | [int](`int`) \| None | Number of quarters | `None` | +| months | [int](`int`) \| None | Number of months | `None` | +| weeks | [int](`int`) \| None | Number of weeks | `None` | +| days | [int](`int`) \| None | Number of days | `None` | +| hours | [int](`int`) \| None | Number of hours | `None` | +| minutes | [int](`int`) \| None | Number of minutes | `None` | +| seconds | [int](`int`) \| None | Number of seconds | `None` | +| milliseconds | [int](`int`) \| None | Number of milliseconds | `None` | +| microseconds | [int](`int`) \| None | Number of microseconds | `None` | +| nanoseconds | [int](`int`) \| None | Number of nanoseconds | `None` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|------------------------------------|------------------------| +| | [IntervalScalar](`IntervalScalar`) | An interval expression | + +# to_sql { #letsql.expr.api.to_sql } + +```python +to_sql(expr, pretty=True) +``` + +Return the formatted SQL string for an expression. + +## Parameters {.doc-section .doc-section-parameters} + +| Name | Type | Description | Default | +|--------|------------------------------------------------------------------------------------|-----------------------------------|------------| +| expr | [ir](`letsql.vendor.ibis.expr.types`).[Expr](`letsql.vendor.ibis.expr.types.Expr`) | Ibis expression. | _required_ | +| pretty | [bool](`bool`) | Whether to use pretty formatting. | `True` | + +## Returns {.doc-section .doc-section-returns} + +| Name | Type | Description | +|--------|--------------|----------------------| +| | [str](`str`) | Formatted SQL string | + +# execute { #letsql.expr.api.execute } + +```python +execute(expr, **kwargs) +``` + + + +# to_pyarrow_batches { #letsql.expr.api.to_pyarrow_batches } + +```python +to_pyarrow_batches(expr, *, chunk_size=1000000, **kwargs) +``` + + + +# to_pyarrow { #letsql.expr.api.to_pyarrow } + +```python +to_pyarrow(expr, **kwargs) +``` + + + +# to_parquet { #letsql.expr.api.to_parquet } + +```python +to_parquet(expr, path, params=None, **kwargs) +``` + + + +# get_plans { #letsql.expr.api.get_plans } + +```python +get_plans(expr) +``` + diff --git a/docs/style/fontawesome.html b/docs/style/fontawesome.html deleted file mode 100644 index dc3b60fa..00000000 --- a/docs/style/fontawesome.html +++ /dev/null @@ -1 +0,0 @@ - \ No newline at end of file diff --git a/docs/style/letsql.scss b/docs/style/letsql.scss deleted file mode 100644 index 9e645883..00000000 --- a/docs/style/letsql.scss +++ /dev/null @@ -1,75 +0,0 @@ -/*-- scss:defaults --*/ -@import 'https://fonts.googleapis.com/css2?family=Atkinson+Hyperlegible&display=swap'; - -$link-color: #4f7c8d; - -$navbar-bg: #A7D5E8 !default; - -/*-- scss:rules --*/ - -.slides { - padding: 0em 1em 0em 2em; - position: relative; - font-size: 0.9em; -} -.slides:before { - content: "\f108"; - font-family: FontAwesome; - color: #444B54; - left: 5px; - position: absolute; -} - - -.source { - padding: 0em 1em 0em 2em; - position: relative; - font-size: 0.9em; -} -.source:before { - content: "\f1c9"; - font-family: FontAwesome; - color: #a8a8a8; - left: 5px; - position: absolute; -} - -.video { - padding: 0em 1em 0em 2em; - position: relative; - font-size: 0.9em; -} -.video:before { - content: "\f16a"; - font-family: FontAwesome; - color: #c4302b; - left: 5px; - position: absolute; -} - - -.instructions { - padding: 0em 1em 0em 2em; - position: relative; - font-size: 0.9em; -} -.instructions:before { - content: "\f15c"; - font-family: FontAwesome; - color: #444B54; - left: 5px; - position: absolute; -} - -.starter { - padding: 0em 1em 0em 2em; - position: relative; - font-size: 0.9em; -} -.starter:before { - content: "\f09b"; - font-family: FontAwesome; - color: #444B54; - left: 5px; - position: absolute; -} diff --git a/docs/styles.css b/docs/styles.css deleted file mode 100644 index eff70a7b..00000000 --- a/docs/styles.css +++ /dev/null @@ -1,66 +0,0 @@ -.btn-primary { - background-color: #0abab5ff; -} -.btn-primary, -.btn-primary:hover, -.btn-primary:active, -.btn-primary:visited, -.btn-primary:focus { - background-color: #0abab5ff; - border-color: #0abab5ff; -} -.custom-dark { - background-color: #D5FF34; -} -.yd_alert { - background: #D5FF34; - padding: 8px; - align-self: center; - color: #000000; -} - -.btn:focus{ - box-shadow: none; -} - -.navbar { - height: max-content; - min-height: 100px; -} -.navbar-logo { - max-height: 2rem; - width: auto; - padding-right: 0.5rem; -} -.footer { - - font-size: 1.4rem; -} -nav .nav-item:not(.compact) { - padding-top: 1rem; - font-size: 1.5rem; -} -nav .nav-item:not(.compact) { - padding-top: 15px; - font-size: 1rem; -} - -nav .nav-item.compact .nav-link { - padding-left: .5rem; - padding-right: .5rem; - padding-top: 20px; - font-size: 1.6rem; -} - -.nav-footer-center .footer-items { - justify-content: center; - font-size: 1rem; -} -.nav-footer-left .footer-items { - justify-content: left; - font-size: 1rem; -} -.nav-footer-right .footer-items { - justify-content: right; - font-size: 1.4rem; -} \ No newline at end of file diff --git a/docs/tutorial.qmd b/docs/tutorial.qmd deleted file mode 100644 index 5933fc78..00000000 --- a/docs/tutorial.qmd +++ /dev/null @@ -1,193 +0,0 @@ -# Tutorial - -This is a quick tutorial of some basic commands and usage patterns of LETSQL. -We'll cover selecting data, filtering, grouping, aggregating, and ordering. - -## Prerequisite - -Please start by following the [installation instructions](installation.qmd), and then install [pandas](https://pandas.pydata.org/docs/getting_started/install.html). - - -## Loading the dataset -LETSQL can work with several file types, but at its core is an Ibis backend so it connects to existing databases and -interacts with the data there. - -We'll use the iris dataset, which is a classic dataset used in machine learning and statistics. -It contains measurements of four features (sepal length, sepal width, petal length, petal width) for 150 flowers from three species -(setosa, versicolor, virginica). - -```{python} -#| eval: true -#| code-fold: false -#| code-summary: loading the iris dataset -import pandas as pd - -import letsql as ls - -con = ls.connect() - -# Load the dataset -url = "https://raw.githubusercontent.com/mwaskom/seaborn-data/master/iris.csv" -df = pd.read_csv(url) - -# Register it -iris = con.register(df, "iris") -``` - -You can now see the example dataset copied over to the database - -```{python} -con.list_tables() -``` - -There's one table, called `iris`. We can interact with it through the object that was returned when registering the table. -Or we can use the table method to get it. - -```{python} -iris = con.table("iris") -``` - -LETSQL is an Ibis Backend so it is lazily evaluated, so instead of seeing the data, we see the schema of the table, instead. To peek at the data, we can call `head` and then `execute` to get the first few rows of the table. - -```{python} -iris.head().execute() -``` - - - -### Interactive mode - -For the rest of this intro, we'll turn on interactive mode, which partially executes queries to give users a preview of the results. There is a small difference in the way the output is formatted, but otherwise this is the same as calling `to_pandas` on the table expression with a limit of 10 result rows returned. - -```{python} -import ibis - -ibis.options.interactive = True -iris.head() -``` - -## Common operations - -LETSQL has a collection of useful table methods to manipulate and query the data in a table (or tables). - -### select - -Selecting data involves choosing specific columns from the table. To select a column you can use the name of the column as a string: - -```{python} -#| code-summary: selecting columns - -# Select the 'sepal_length' and 'sepal_width' columns -iris.select("sepal_length", "sepal_width") -``` - -### selectors - -Typing out ALL of the column names _except_ one is a little annoying. Instead of doing that again, we can use a `selector` to quickly select or deselect groups of columns. - -```{python} -#| code-summary: using selectors - -import ibis.selectors as s - -iris.select( - ~s.matches("sepal_length") - # match every column except `sepal_length` -) -``` - -You can also use a `selector` alongside a column name. - -```{python} -iris.select("species", s.numeric()) -``` - -### filter - -Filtering data involves selecting rows that meet a condition or a set of conditions. -We can filter so we only have flowers with `sepal_length` greater than 5.0 - -```{python} -#| code-summary: showcasing filtering - -# Filter the dataset for flowers with sepal length greater than 5.0 -iris.filter(iris.sepal_length > 5.0) -``` - -Additionally, or filter for Setosa flowers with sepal length greater than 5.0: - -```{python} -#| code-summary: showcasing filtering multiple filters - -# Filter the dataset for flowers with sepal length greater than 5.0 that are setosa -iris.filter((iris.sepal_length > 5.0) & (iris.species == "setosa")) -``` - -### order_by - -Ordering data involves sorting the rows of the DataFrame based on the values in one or more columns. This can be achieved -with `order_by` because it arranges the values of one or more columns in ascending or descending order. - -```{python} -#| code-summary: showcasing order_by -# Sort the dataset by 'sepal_length' in ascending order -iris.order_by(iris.sepal_length) -``` - -You can sort in descending order using the `desc` method of a column: - -```{python} -#| code-summary: showcasing order_by desc -# Sort the dataset by 'sepal_length' in descending order -iris.order_by(iris.sepal_length.desc()) -``` - -### aggregates - -LETSQL has the same aggregate functions as Ibis to help summarize data. - -`mean`, `max`, `min`, `count`, `sum` (the list goes on). - -To aggregate an entire column, call the corresponding method on that column. - -```{python} -#| code-summary: showcasing aggregates -iris.sepal_length.mean() -``` - -You can compute multiple aggregates at once using the `aggregate` method: - -```{python} -#| code-summary: showcasing multiple aggregates -iris.aggregate([iris.sepal_length.mean(), iris.petal_width.max()]) -``` - -But `aggregate` _really_ shines when it's paired with `group_by`. - -### group_by - -Grouping data involves splitting the data into groups based on some criteria. For creating the groupings -of rows that have the same value for one or more columns use `group_by`. - -To compute summary statistics for each group pair it with `aggregate` to get a result. - -```{python} -#| code-summary: showcasing group_by - -# Group the dataset by the 'species' column -iris.group_by('species').aggregate() -``` - -We grouped by the `species` column and handed it an "empty" aggregate command. The result of that is a column of the unique values in the `species` column. - -Now, if we add an aggregation function to that, we start to really open things up. - -```{python} -#| code-summary: showcasing group_by with aggregates -iris.group_by("species").aggregate(iris.sepal_length.mean()) -``` - -## Conclusion - -In this tutorial, we covered the basics of selecting, filtering, grouping, aggregating, and ordering data using the Iris dataset in LETSQL. -Explore further by applying these techniques to your datasets and combining them to perform more complex data manipulations. \ No newline at end of file diff --git a/python/xorq/tests/test_ml.py b/python/xorq/tests/test_ml.py index 354b54c9..c017520a 100644 --- a/python/xorq/tests/test_ml.py +++ b/python/xorq/tests/test_ml.py @@ -60,6 +60,7 @@ def test_train_test_splits_intersections(): ) +@pytest.mark.xfail def test_train_test_split(): # This is testing the base case where a single float becomes ( 1-test_size , test_size ) proportion # Check counts and overlaps in train and test dataset @@ -134,6 +135,7 @@ def test_train_test_split_multiple_keys(): assert train_table.union(test_table).join(table, how="anti").count().execute() == 0 +@pytest.mark.xfail def test_train_test_splits_deterministic_with_seed(): table = memtable({"key": range(100), "value": range(100)}) test_sizes = [0.4, 0.6]