Expose Transforms to Python Binding

.github/workflows/bindings_python_ci.yml

@@ -80,4 +80,4 @@ jobs:
           set -e
           pip install hatch==1.12.0
           hatch run dev:pip install dist/pyiceberg_core-*.whl --force-reinstall
-          hatch run dev:test
+          hatch run dev:test

.gitignore

@@ -24,3 +24,5 @@ dist/*
 **/venv
 *.so
 *.pyc
+*.whl
+*.tar.gz

bindings/python/Cargo.toml

@@ -32,4 +32,5 @@ crate-type = ["cdylib"]
 
 [dependencies]
 iceberg = { path = "../../crates/iceberg" }
-pyo3 = { version = "0.22", features = ["extension-module"] }
+pyo3 = { version = "0.21.1", features = ["extension-module"] }
+arrow = { version = "52.2.0", features = ["pyarrow"] }

bindings/python/pyproject.toml

@@ -43,6 +43,7 @@ ignore = ["F403", "F405"]
 dependencies = [
     "maturin>=1.0,<2.0",
     "pytest>=8.3.2",
+    "pyarrow>=17.0.0",
 ]
 
 [tool.hatch.envs.dev.scripts]

bindings/python/src/lib.rs

@@ -17,6 +17,9 @@
 
 use iceberg::io::FileIOBuilder;
 use pyo3::prelude::*;
+use pyo3::wrap_pyfunction;
+
+mod transform;
 
 #[pyfunction]
 fn hello_world() -> PyResult<String> {
@@ -25,7 +28,25 @@ fn hello_world() -> PyResult<String> {
 }
 
 #[pymodule]
-fn pyiceberg_core_rust(m: &Bound<'_, PyModule>) -> PyResult<()> {
+fn submodule(_py: Python, module: &Bound<'_, PyModule>) -> PyResult<()> {
+    use transform::bucket_transform;
+
+    module.add_wrapped(wrap_pyfunction!(bucket_transform))?;
+    Ok(())
+}
+
+#[pymodule]
+fn pyiceberg_core_rust(py: Python, m: &Bound<'_, PyModule>) -> PyResult<()> {
     m.add_function(wrap_pyfunction!(hello_world, m)?)?;
+
+    // https://github.com/PyO3/pyo3/issues/759
+    // Submodules added through PyO3 cannot be imported in Python using
+    // the syntax: 'from parent.child import function'. 
+    // We need to add the submodule in sys.modules manually so that 
+    // Python can find it.
+    let child_module = PyModule::new_bound(py, "pyiceberg_core.transform")?;
+    submodule(py, &child_module)?;
+    m.add("transform", child_module.clone())?;
+    py.import_bound("sys")?.getattr("modules")?.set_item("pyiceberg_core.transform", child_module)?;
     Ok(())
 }

bindings/python/src/transform.rs

@@ -0,0 +1,75 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use std::{error, fmt};
+use iceberg::spec::Transform;
+use iceberg::transform::create_transform_function;
+use iceberg::Error;
+
+use arrow::{
+    array::{make_array, Array, ArrayData},
+};
+use arrow::pyarrow::{FromPyArrow, ToPyArrow};
+use pyo3::{exceptions::PyValueError, prelude::*};
+
+#[derive(Debug)]
+enum PyO3IcebergError {
+    Error(Error),
+}
+
+impl fmt::Display for PyO3IcebergError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            PyO3IcebergError::Error(ref e) => e.fmt(f),
+        }
+    }
+}
+
+impl error::Error for PyO3IcebergError {
+    fn source(&self) -> Option<&(dyn error::Error + 'static)> {
+        match *self {
+            // The cause is the underlying implementation error type. Is implicitly
+            // cast to the trait object `&error::Error`. This works because the
+            // underlying type already implements the `Error` trait.
+            PyO3IcebergError::Error(ref e) => Some(e),
+        }
+    }
+}
+
+impl From<Error> for PyO3IcebergError {
+    fn from(err: Error) -> PyO3IcebergError {
+        PyO3IcebergError::Error(err)
+    }
+}
+
+impl From<PyO3IcebergError> for PyErr {
+    fn from(err: PyO3IcebergError) -> PyErr {
+        PyValueError::new_err(err.to_string())
+    }
+}
+
+#[pyfunction]
+pub fn bucket_transform(array: PyObject, num_buckets: u32, py: Python) -> PyResult<PyObject> {
+    // import
+    let array = ArrayData::from_pyarrow_bound(array.bind(py))?;
+    let array = make_array(array);
+    let bucket = create_transform_function(&Transform::Bucket(num_buckets)).map_err(PyO3IcebergError::from)?;
+    let array = bucket.transform(array).map_err(PyO3IcebergError::from)?;
+    // export
+    let array = array.into_data();
+    array.to_pyarrow(py)
+}

bindings/python/tests/test_transform.py

@@ -0,0 +1,49 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from pyiceberg_core.transform import bucket_transform
+
+import pytest
+import pyarrow as pa
+
+
+def test_bucket_pyarrow_array():
+    arr = pa.array([1, 2])
+    result = bucket_transform(arr, 10)
+    expected = pa.array([6, 2], type=pa.int32())
+    assert result == expected
+
+
+def test_bucket_pyarrow_array_list_type_fails():
+    arr = pa.array([[1, 2], [3, 4]])
+    with pytest.raises(
+        ValueError,
+        match=r"FeatureUnsupported => Unsupported data type for bucket transform",
+    ):
+        bucket_transform(arr, 10)
+
+
+def test_bucket_chunked_array():
+    chunked = pa.chunked_array([pa.array([1, 2]), pa.array([3, 4])])
+    result_chunks = []
+    for arr in chunked.iterchunks():
+        result_chunks.append(bucket_transform(arr, 10))
+
+    expected = pa.chunked_array(
+        [pa.array([6, 2], type=pa.int32()), pa.array([5, 0], type=pa.int32())]
+    )
+    assert pa.chunked_array(result_chunks).equals(expected)