DEPR: categorical.take allow_fill default (#29912)

Author: jbrockmendel

doc/source/whatsnew/v1.0.0.rst

@@ -365,6 +365,7 @@ Deprecations
   is equivalent to ``arr[idx.get_loc(idx_val)] = val``, which should be used instead (:issue:`28621`).
 - :func:`is_extension_type` is deprecated, :func:`is_extension_array_dtype` should be used instead (:issue:`29457`)
 - :func:`eval` keyword argument "truediv" is deprecated and will be removed in a future version (:issue:`29812`)
+- :meth:`Categorical.take_nd` is deprecated, use :meth:`Categorical.take` instead (:issue:`27745`)
 
 .. _whatsnew_1000.prior_deprecations:
 
@@ -457,6 +458,7 @@ or ``matplotlib.Axes.plot``. See :ref:`plotting.formatters` for more.
 - In :func:`concat` the default value for ``sort`` has been changed from ``None`` to ``False`` (:issue:`20613`)
 - Removed previously deprecated "raise_conflict" argument from :meth:`DataFrame.update`, use "errors" instead (:issue:`23585`)
 - Removed previously deprecated keyword "n" from :meth:`DatetimeIndex.shift`, :meth:`TimedeltaIndex.shift`, :meth:`PeriodIndex.shift`, use "periods" instead (:issue:`22458`)
+- Changed the default ``fill_value`` in :meth:`Categorical.take` from ``True`` to ``False`` (:issue:`20841`)
 - Changed the default value for the `raw` argument in :func:`Series.rolling().apply() <pandas.core.window.Rolling.apply>`, :func:`DataFrame.rolling().apply() <pandas.core.window.Rolling.apply>`,
 - :func:`Series.expanding().apply() <pandas.core.window.Expanding.apply>`, and :func:`DataFrame.expanding().apply() <pandas.core.window.Expanding.apply>` to ``False`` (:issue:`20584`)
 - Changed :meth:`Timedelta.resolution` to match the behavior of the standard library ``datetime.timedelta.resolution``, for the old behavior, use :meth:`Timedelta.resolution_string` (:issue:`26839`)

pandas/core/arrays/categorical.py

@@ -1,6 +1,5 @@
 import operator
 from shutil import get_terminal_size
-import textwrap
 from typing import Type, Union, cast
 from warnings import warn
 
@@ -59,18 +58,6 @@
 
 from .base import ExtensionArray, _extension_array_shared_docs, try_cast_to_ea
 
-_take_msg = textwrap.dedent(
-    """\
-    Interpreting negative values in 'indexer' as missing values.
-    In the future, this will change to meaning positional indices
-    from the right.
-
-    Use 'allow_fill=True' to retain the previous behavior and silence this
-    warning.
-
-    Use 'allow_fill=False' to accept the new behavior."""
-)
-
 
 def _cat_compare_op(op):
     opname = f"__{op.__name__}__"
@@ -1829,7 +1816,7 @@ def fillna(self, value=None, method=None, limit=None):
 
         return self._constructor(codes, dtype=self.dtype, fastpath=True)
 
-    def take_nd(self, indexer, allow_fill=None, fill_value=None):
+    def take(self, indexer, allow_fill: bool = False, fill_value=None):
         """
         Take elements from the Categorical.
 
@@ -1838,7 +1825,7 @@ def take_nd(self, indexer, allow_fill=None, fill_value=None):
         indexer : sequence of int
             The indices in `self` to take. The meaning of negative values in
             `indexer` depends on the value of `allow_fill`.
-        allow_fill : bool, default None
+        allow_fill : bool, default False
             How to handle negative values in `indexer`.
 
             * False: negative values in `indices` indicate positional indices
@@ -1849,11 +1836,9 @@ def take_nd(self, indexer, allow_fill=None, fill_value=None):
               (the default). These values are set to `fill_value`. Any other
               other negative values raise a ``ValueError``.
 
-            .. versionchanged:: 0.23.0
+            .. versionchanged:: 1.0.0
 
-               Deprecated the default value of `allow_fill`. The deprecated
-               default is ``True``. In the future, this will change to
-               ``False``.
+               Default value changed from ``True`` to ``False``.
 
         fill_value : object
             The value to use for `indices` that are missing (-1), when
@@ -1903,10 +1888,6 @@ def take_nd(self, indexer, allow_fill=None, fill_value=None):
         will raise a ``TypeError``.
         """
         indexer = np.asarray(indexer, dtype=np.intp)
-        if allow_fill is None:
-            if (indexer < 0).any():
-                warn(_take_msg, FutureWarning, stacklevel=2)
-                allow_fill = True
 
         dtype = self.dtype
 
@@ -1927,7 +1908,14 @@ def take_nd(self, indexer, allow_fill=None, fill_value=None):
         result = type(self).from_codes(codes, dtype=dtype)
         return result
 
-    take = take_nd
+    def take_nd(self, indexer, allow_fill: bool = False, fill_value=None):
+        # GH#27745 deprecate alias that other EAs dont have
+        warn(
+            "Categorical.take_nd is deprecated, use Categorical.take instead",
+            FutureWarning,
+            stacklevel=2,
+        )
+        return self.take(indexer, allow_fill=allow_fill, fill_value=fill_value)
 
     def __len__(self) -> int:
         """

pandas/tests/arrays/categorical/test_algos.py

@@ -89,10 +89,12 @@ def test_isin_empty(empty):
 class TestTake:
     # https://github.com/pandas-dev/pandas/issues/20664
 
-    def test_take_warns(self):
+    def test_take_default_allow_fill(self):
         cat = pd.Categorical(["a", "b"])
-        with tm.assert_produces_warning(FutureWarning):
-            cat.take([0, -1])
+        with tm.assert_produces_warning(None):
+            result = cat.take([0, -1])
+
+        assert result.equals(cat)
 
     def test_take_positive_no_warning(self):
         cat = pd.Categorical(["a", "b"])
@@ -158,3 +160,8 @@ def test_take_fill_value_new_raises(self):
         xpr = r"'fill_value' \('d'\) is not in this Categorical's categories."
         with pytest.raises(TypeError, match=xpr):
             cat.take([0, 1, -1], fill_value="d", allow_fill=True)
+
+    def test_take_nd_deprecated(self):
+        cat = pd.Categorical(["a", "b", "c"])
+        with tm.assert_produces_warning(FutureWarning):
+            cat.take_nd([0, 1])