DEPR: allowing unknowns in take (pandas-dev#52981)

* DEPR: allowing unknowns in take

* GH ref

Author: jbrockmendel

doc/source/whatsnew/v2.1.0.rst

@@ -253,6 +253,7 @@ Deprecations
 - Deprecated :meth:`DataFrame.applymap`. Use the new :meth:`DataFrame.map` method instead (:issue:`52353`)
 - Deprecated :meth:`DataFrame.swapaxes` and :meth:`Series.swapaxes`, use :meth:`DataFrame.transpose` or :meth:`Series.transpose` instead (:issue:`51946`)
 - Deprecated ``freq`` parameter in :class:`PeriodArray` constructor, pass ``dtype`` instead (:issue:`52462`)
+- Deprecated allowing non-standard inputs in :func:`take`, pass either a ``numpy.ndarray``, :class:`ExtensionArray`, :class:`Index`, or :class:`Series` (:issue:`52981`)
 - Deprecated behavior of :class:`DataFrame` reductions ``sum``, ``prod``, ``std``, ``var``, ``sem`` with ``axis=None``, in a future version this will operate over both axes returning a scalar instead of behaving like ``axis=0``; note this also affects numpy functions e.g. ``np.sum(df)`` (:issue:`21597`)
 - Deprecated behavior of :func:`concat` when :class:`DataFrame` has columns that are all-NA, in a future version these will not be discarded when determining the resulting dtype (:issue:`40893`)
 - Deprecated behavior of :meth:`Series.dt.to_pydatetime`, in a future version this will return a :class:`Series` containing python ``datetime`` objects instead of an ``ndarray`` of datetimes; this matches the behavior of other :meth:`Series.dt` properties (:issue:`20306`)

pandas/core/algorithms.py

@@ -1175,6 +1175,11 @@ def take(
     arr : array-like or scalar value
         Non array-likes (sequences/scalars without a dtype) are coerced
         to an ndarray.
+
+        .. deprecated:: 2.1.0
+            Passing an argument other than a numpy.ndarray, ExtensionArray,
+            Index, or Series is deprecated.
+
     indices : sequence of int or one-dimensional np.ndarray of int
         Indices to be taken.
     axis : int, default 0
@@ -1240,6 +1245,16 @@ def take(
     ...      fill_value=-10)
     array([ 10,  10, -10])
     """
+    if not isinstance(arr, (np.ndarray, ABCExtensionArray, ABCIndex, ABCSeries)):
+        # GH#52981
+        warnings.warn(
+            "pd.api.extensions.take accepting non-standard inputs is deprecated "
+            "and will raise in a future version. Pass either a numpy.ndarray, "
+            "ExtensionArray, Index, or Series instead.",
+            FutureWarning,
+            stacklevel=find_stack_level(),
+        )
+
     if not is_array_like(arr):
         arr = np.asarray(arr)
 

pandas/tests/test_take.py

@@ -301,6 +301,8 @@ def test_take_na_empty(self):
 
     def test_take_coerces_list(self):
         arr = [1, 2, 3]
-        result = algos.take(arr, [0, 0])
+        msg = "take accepting non-standard inputs is deprecated"
+        with tm.assert_produces_warning(FutureWarning, match=msg):
+            result = algos.take(arr, [0, 0])
         expected = np.array([1, 1])
         tm.assert_numpy_array_equal(result, expected)