fixes #363

fastcore/_nbdev.py

@@ -92,6 +92,9 @@
          "nested_idx": "01_basics.ipynb",
          "val2idx": "01_basics.ipynb",
          "uniqueify": "01_basics.ipynb",
+         "loop_first_last": "01_basics.ipynb",
+         "loop_first": "01_basics.ipynb",
+         "loop_last": "01_basics.ipynb",
          "num_methods": "01_basics.ipynb",
          "rnum_methods": "01_basics.ipynb",
          "inum_methods": "01_basics.ipynb",

fastcore/basics.py

@@ -9,11 +9,11 @@
            'delegate_attr', 'ShowPrint', 'Int', 'Str', 'Float', 'concat', 'strcat', 'detuplify', 'replicate', 'setify',
            'merge', 'range_of', 'groupby', 'last_index', 'filter_dict', 'filter_keys', 'filter_values', 'cycle',
            'zip_cycle', 'sorted_ex', 'not_', 'argwhere', 'filter_ex', 'range_of', 'renumerate', 'first', 'nested_attr',
-           'nested_idx', 'val2idx', 'uniqueify', 'num_methods', 'rnum_methods', 'inum_methods', 'fastuple', 'arg0',
-           'arg1', 'arg2', 'arg3', 'arg4', 'bind', 'mapt', 'map_ex', 'compose', 'maps', 'partialler', 'instantiate',
-           'using_attr', 'Self', 'Self', 'copy_func', 'patch_to', 'patch', 'patch_property', 'compile_re', 'ImportEnum',
-           'StrEnum', 'str_enum', 'Stateful', 'PrettyString', 'even_mults', 'num_cpus', 'add_props', 'typed',
-           'exec_new']
+           'nested_idx', 'val2idx', 'uniqueify', 'loop_first_last', 'loop_first', 'loop_last', 'num_methods',
+           'rnum_methods', 'inum_methods', 'fastuple', 'arg0', 'arg1', 'arg2', 'arg3', 'arg4', 'bind', 'mapt', 'map_ex',
+           'compose', 'maps', 'partialler', 'instantiate', 'using_attr', 'Self', 'Self', 'copy_func', 'patch_to',
+           'patch', 'patch_property', 'compile_re', 'ImportEnum', 'StrEnum', 'str_enum', 'Stateful', 'PrettyString',
+           'even_mults', 'num_cpus', 'add_props', 'typed', 'exec_new']
 
 # Cell
 from .imports import *
@@ -576,6 +576,30 @@ def uniqueify(x, sort=False, bidir=False, start=None):
     if sort: res.sort()
     return (res,val2idx(res)) if bidir else res
 
+# Cell
+
+# looping functions from https://github.com/willmcgugan/rich/blob/master/rich/_loop.py
+def loop_first_last(values):
+    "Iterate and generate a tuple with a flag for first and last value."
+    iter_values = iter(values)
+    try: previous_value = next(iter_values)
+    except StopIteration: return
+    first = True
+    for value in iter_values:
+        yield first,False,previous_value
+        first,previous_value = False,value
+    yield first,True,previous_value
+
+# Cell
+def loop_first(values):
+    "Iterate and generate a tuple with a flag for first and last value."
+    return ((b,o) for b,_,o in loop_first_last(values))
+
+# Cell
+def loop_last(values):
+    "Iterate and generate a tuple with a flag for first and last value."
+    return ((b,o) for _,b,o in loop_first_last(values))
+
 # Cell
 num_methods = """
     __add__ __sub__ __mul__ __matmul__ __truediv__ __floordiv__ __mod__ __divmod__ __pow__

nbs/01_basics.ipynb

@@ -3363,6 +3363,78 @@
     "test_eq(o,{0:0, 1: 1, 3: 2, 5: 3})"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#export\n",
+    "\n",
+    "# looping functions from https://github.com/willmcgugan/rich/blob/master/rich/_loop.py\n",
+    "def loop_first_last(values):\n",
+    "    \"Iterate and generate a tuple with a flag for first and last value.\"\n",
+    "    iter_values = iter(values)\n",
+    "    try: previous_value = next(iter_values)\n",
+    "    except StopIteration: return\n",
+    "    first = True\n",
+    "    for value in iter_values:\n",
+    "        yield first,False,previous_value\n",
+    "        first,previous_value = False,value\n",
+    "    yield first,True,previous_value"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "test_eq(loop_first_last(range(3)), [(True,False,0), (False,False,1), (False,True,2)])"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#export\n",
+    "def loop_first(values):\n",
+    "    \"Iterate and generate a tuple with a flag for first and last value.\"\n",
+    "    return ((b,o) for b,_,o in loop_first_last(values))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "test_eq(loop_first(range(3)), [(True,0), (False,1), (False,2)])"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#export\n",
+    "def loop_last(values):\n",
+    "    \"Iterate and generate a tuple with a flag for first and last value.\"\n",
+    "    return ((b,o) for _,b,o in loop_first_last(values))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "test_eq(loop_last(range(3)), [(False,0), (False,1), (True,2)])"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -3585,8 +3657,13 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "#### Other Elementwise Operations\n",
-    "\n",
+    "#### Other Elementwise Operations"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
     "Additionally, the following elementwise operations are available:\n",
     "- `le`: less than or equal\n",
     "- `eq`: equal\n",