DEPR: object-dtype bool_only (#49371)

Author: jbrockmendel

doc/source/whatsnew/v2.0.0.rst

@@ -258,6 +258,8 @@ Removal of prior version deprecations/changes
 - Changed behavior of :class:`DataFrame` constructor when passed a ``dtype`` (other than int) that the data cannot be cast to; it now raises instead of silently ignoring the dtype (:issue:`41733`)
 - Changed the behavior of :class:`Series` constructor, it will no longer infer a datetime64 or timedelta64 dtype from string entries (:issue:`41731`)
 - Changed behavior of :class:`Index` constructor when passed a ``SparseArray`` or ``SparseDtype`` to retain that dtype instead of casting to ``numpy.ndarray`` (:issue:`43930`)
+- Changed behavior of :meth:`DataFrame.any` and :meth:`DataFrame.all` with ``bool_only=True``; object-dtype columns with all-bool values will no longer be included, manually cast to ``bool`` dtype first (:issue:`46188`)
+-
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_200.performance:

pandas/core/dtypes/inference.py

@@ -6,13 +6,10 @@
 from numbers import Number
 import re
 from typing import Pattern
-import warnings
 
 import numpy as np
 
 from pandas._libs import lib
-from pandas._typing import ArrayLike
-from pandas.util._exceptions import find_stack_level
 
 is_bool = lib.is_bool
 
@@ -425,42 +422,3 @@ def is_dataclass(item):
         return is_dataclass(item) and not isinstance(item, type)
     except ImportError:
         return False
-
-
-def is_inferred_bool_dtype(arr: ArrayLike) -> bool:
-    """
-    Check if this is a ndarray[bool] or an ndarray[object] of bool objects.
-
-    Parameters
-    ----------
-    arr : np.ndarray or ExtensionArray
-
-    Returns
-    -------
-    bool
-
-    Notes
-    -----
-    This does not include the special treatment is_bool_dtype uses for
-    Categorical.
-    """
-    if not isinstance(arr, np.ndarray):
-        return False
-
-    dtype = arr.dtype
-    if dtype == np.dtype(bool):
-        return True
-    elif dtype == np.dtype("object"):
-        result = lib.is_bool_array(arr)
-        if result:
-            # GH#46188
-            warnings.warn(
-                "In a future version, object-dtype columns with all-bool values "
-                "will not be included in reductions with bool_only=True. "
-                "Explicitly cast to bool dtype instead.",
-                FutureWarning,
-                stacklevel=find_stack_level(),
-            )
-        return result
-
-    return False

pandas/core/internals/array_manager.py

@@ -52,7 +52,6 @@
     ABCDataFrame,
     ABCSeries,
 )
-from pandas.core.dtypes.inference import is_inferred_bool_dtype
 from pandas.core.dtypes.missing import (
     array_equals,
     isna,
@@ -488,7 +487,7 @@ def get_bool_data(self: T, copy: bool = False) -> T:
         copy : bool, default False
             Whether to copy the blocks
         """
-        return self._get_data_subset(is_inferred_bool_dtype)
+        return self._get_data_subset(lambda x: x.dtype == np.dtype(bool))
 
     def get_numeric_data(self: T, copy: bool = False) -> T:
         """

pandas/core/internals/blocks.py

@@ -70,7 +70,6 @@
     ABCPandasArray,
     ABCSeries,
 )
-from pandas.core.dtypes.inference import is_inferred_bool_dtype
 from pandas.core.dtypes.missing import (
     is_valid_na_for_dtype,
     isna,
@@ -194,7 +193,7 @@ def is_bool(self) -> bool:
         """
         We can be bool if a) we are bool dtype or b) object dtype with bool objects.
         """
-        return is_inferred_bool_dtype(self.values)
+        return self.values.dtype == np.dtype(bool)
 
     @final
     def external_values(self):

pandas/tests/frame/test_reductions.py

@@ -1280,7 +1280,6 @@ def test_any_all_object(self):
         assert result is False
 
     def test_any_all_object_bool_only(self):
-        msg = "object-dtype columns with all-bool values"
 
         df = DataFrame({"A": ["foo", 2], "B": [True, False]}).astype(object)
         df._consolidate_inplace()
@@ -1291,36 +1290,29 @@ def test_any_all_object_bool_only(self):
 
         # The underlying bug is in DataFrame._get_bool_data, so we check
         #  that while we're here
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            res = df._get_bool_data()
-        expected = df[["B", "C"]]
+        res = df._get_bool_data()
+        expected = df[["C"]]
         tm.assert_frame_equal(res, expected)
 
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            res = df.all(bool_only=True, axis=0)
-        expected = Series([False, True], index=["B", "C"])
+        res = df.all(bool_only=True, axis=0)
+        expected = Series([True], index=["C"])
         tm.assert_series_equal(res, expected)
 
         # operating on a subset of columns should not produce a _larger_ Series
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            res = df[["B", "C"]].all(bool_only=True, axis=0)
+        res = df[["B", "C"]].all(bool_only=True, axis=0)
         tm.assert_series_equal(res, expected)
 
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            assert not df.all(bool_only=True, axis=None)
+        assert df.all(bool_only=True, axis=None)
 
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            res = df.any(bool_only=True, axis=0)
-        expected = Series([True, True], index=["B", "C"])
+        res = df.any(bool_only=True, axis=0)
+        expected = Series([True], index=["C"])
         tm.assert_series_equal(res, expected)
 
         # operating on a subset of columns should not produce a _larger_ Series
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            res = df[["B", "C"]].any(bool_only=True, axis=0)
+        res = df[["C"]].any(bool_only=True, axis=0)
         tm.assert_series_equal(res, expected)
 
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            assert df.any(bool_only=True, axis=None)
+        assert df.any(bool_only=True, axis=None)
 
     @pytest.mark.parametrize("method", ["any", "all"])
     def test_any_all_level_axis_none_raises(self, method):

pandas/tests/internals/test_internals.py

@@ -795,17 +795,15 @@ def test_get_numeric_data(self, using_copy_on_write):
             )
 
     def test_get_bool_data(self, using_copy_on_write):
-        msg = "object-dtype columns with all-bool values"
         mgr = create_mgr(
             "int: int; float: float; complex: complex;"
             "str: object; bool: bool; obj: object; dt: datetime",
             item_shape=(3,),
         )
         mgr.iset(6, np.array([True, False, True], dtype=np.object_))
 
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            bools = mgr.get_bool_data()
-        tm.assert_index_equal(bools.items, Index(["bool", "dt"]))
+        bools = mgr.get_bool_data()
+        tm.assert_index_equal(bools.items, Index(["bool"]))
         tm.assert_almost_equal(
             mgr.iget(mgr.items.get_loc("bool")).internal_values(),
             bools.iget(bools.items.get_loc("bool")).internal_values(),
@@ -824,8 +822,7 @@ def test_get_bool_data(self, using_copy_on_write):
             )
 
         # Check sharing
-        with tm.assert_produces_warning(FutureWarning, match=msg):
-            bools2 = mgr.get_bool_data(copy=True)
+        bools2 = mgr.get_bool_data(copy=True)
         bools2.iset(0, np.array([False, True, False]))
         if using_copy_on_write:
             tm.assert_numpy_array_equal(