DEPR: Enforce is_extension_type removal (#48822)

* DEPR: Enforce is_extension_type removal

* Add typing

* import future

* Add whatsnew

Author: mroeschke

doc/source/reference/arrays.rst

@@ -630,7 +630,6 @@ Data type introspection
     api.types.is_datetime64_dtype
     api.types.is_datetime64_ns_dtype
     api.types.is_datetime64tz_dtype
-    api.types.is_extension_type
     api.types.is_extension_array_dtype
     api.types.is_float_dtype
     api.types.is_int64_dtype

doc/source/whatsnew/v2.0.0.rst

@@ -145,6 +145,7 @@ Deprecations
 Removal of prior version deprecations/changes
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 - Disallow passing non-round floats to :class:`Timestamp` with ``unit="M"`` or ``unit="Y"`` (:issue:`47266`)
+- Removed :func:`is_extension_type` in favor of :func:`is_extension_array_dtype` (:issue:`29457`)
 - Remove :meth:`DataFrameGroupBy.pad` and :meth:`DataFrameGroupBy.backfill` (:issue:`45076`)
 
 .. ---------------------------------------------------------------------------

pandas/conftest.py

@@ -155,7 +155,6 @@ def pytest_collection_modifyitems(items, config) -> None:
         ("Series.append", "The series.append method is deprecated"),
         ("dtypes.common.is_categorical", "is_categorical is deprecated"),
         ("Categorical.replace", "Categorical.replace is deprecated"),
-        ("dtypes.common.is_extension_type", "'is_extension_type' is deprecated"),
         ("Index.is_mixed", "Index.is_mixed is deprecated"),
         ("MultiIndex._is_lexsorted", "MultiIndex.is_lexsorted is deprecated"),
         # Docstring divides by zero to show behavior difference

pandas/core/arrays/sparse/array.py

@@ -1383,7 +1383,7 @@ def map(self: SparseArrayT, mapper) -> SparseArrayT:
         Indices: array([1, 2], dtype=int32)
         """
         # this is used in apply.
-        # We get hit since we're an "is_extension_type" but regular extension
+        # We get hit since we're an "is_extension_array_dtype" but regular extension
         # types are not hit. This may be worth adding to the interface.
         if isinstance(mapper, ABCSeries):
             mapper = mapper.to_dict()

pandas/core/dtypes/api.py

@@ -13,7 +13,6 @@
     is_dict_like,
     is_dtype_equal,
     is_extension_array_dtype,
-    is_extension_type,
     is_file_like,
     is_float,
     is_float_dtype,
@@ -57,7 +56,6 @@
     "is_dict_like",
     "is_dtype_equal",
     "is_extension_array_dtype",
-    "is_extension_type",
     "is_file_like",
     "is_float",
     "is_float_dtype",

pandas/core/dtypes/common.py

@@ -1336,71 +1336,6 @@ def is_bool_dtype(arr_or_dtype) -> bool:
     return issubclass(dtype.type, np.bool_)
 
 
-def is_extension_type(arr) -> bool:
-    """
-    Check whether an array-like is of a pandas extension class instance.
-
-    .. deprecated:: 1.0.0
-        Use ``is_extension_array_dtype`` instead.
-
-    Extension classes include categoricals, pandas sparse objects (i.e.
-    classes represented within the pandas library and not ones external
-    to it like scipy sparse matrices), and datetime-like arrays.
-
-    Parameters
-    ----------
-    arr : array-like, scalar
-        The array-like to check.
-
-    Returns
-    -------
-    boolean
-        Whether or not the array-like is of a pandas extension class instance.
-
-    Examples
-    --------
-    >>> is_extension_type([1, 2, 3])
-    False
-    >>> is_extension_type(np.array([1, 2, 3]))
-    False
-    >>>
-    >>> cat = pd.Categorical([1, 2, 3])
-    >>>
-    >>> is_extension_type(cat)
-    True
-    >>> is_extension_type(pd.Series(cat))
-    True
-    >>> is_extension_type(pd.arrays.SparseArray([1, 2, 3]))
-    True
-    >>> from scipy.sparse import bsr_matrix
-    >>> is_extension_type(bsr_matrix([1, 2, 3]))
-    False
-    >>> is_extension_type(pd.DatetimeIndex([1, 2, 3]))
-    False
-    >>> is_extension_type(pd.DatetimeIndex([1, 2, 3], tz="US/Eastern"))
-    True
-    >>>
-    >>> dtype = DatetimeTZDtype("ns", tz="US/Eastern")
-    >>> s = pd.Series([], dtype=dtype)
-    >>> is_extension_type(s)
-    True
-    """
-    warnings.warn(
-        "'is_extension_type' is deprecated and will be removed in a future "
-        "version.  Use 'is_extension_array_dtype' instead.",
-        FutureWarning,
-        stacklevel=find_stack_level(),
-    )
-
-    if is_categorical_dtype(arr):
-        return True
-    elif is_sparse(arr):
-        return True
-    elif is_datetime64tz_dtype(arr):
-        return True
-    return False
-
-
 def is_1d_only_ea_obj(obj: Any) -> bool:
     """
     ExtensionArray that does not support 2D, or more specifically that does
@@ -1853,7 +1788,6 @@ def is_all_strings(value: ArrayLike) -> bool:
     "is_dtype_equal",
     "is_ea_or_datetimelike_dtype",
     "is_extension_array_dtype",
-    "is_extension_type",
     "is_file_like",
     "is_float_dtype",
     "is_int64_dtype",

pandas/tests/api/test_types.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import pandas._testing as tm
 from pandas.api import types
 from pandas.tests.api.test_api import Base
@@ -49,7 +51,7 @@ class TestTypes(Base):
         "infer_dtype",
         "is_extension_array_dtype",
     ]
-    deprecated = ["is_extension_type"]
+    deprecated: list[str] = []
     dtypes = ["CategoricalDtype", "DatetimeTZDtype", "PeriodDtype", "IntervalDtype"]
 
     def test_types(self):

pandas/tests/dtypes/test_common.py

@@ -599,36 +599,6 @@ def test_is_bool_dtype_numpy_error():
     assert not com.is_bool_dtype("0 - Name")
 
 
-@pytest.mark.filterwarnings("ignore:'is_extension_type' is deprecated:FutureWarning")
-@pytest.mark.parametrize(
-    "check_scipy", [False, pytest.param(True, marks=td.skip_if_no_scipy)]
-)
-def test_is_extension_type(check_scipy):
-    assert not com.is_extension_type([1, 2, 3])
-    assert not com.is_extension_type(np.array([1, 2, 3]))
-    assert not com.is_extension_type(pd.DatetimeIndex([1, 2, 3]))
-
-    cat = pd.Categorical([1, 2, 3])
-    assert com.is_extension_type(cat)
-    assert com.is_extension_type(pd.Series(cat))
-    assert com.is_extension_type(SparseArray([1, 2, 3]))
-    assert com.is_extension_type(pd.DatetimeIndex(["2000"], tz="US/Eastern"))
-
-    dtype = DatetimeTZDtype("ns", tz="US/Eastern")
-    s = pd.Series([], dtype=dtype)
-    assert com.is_extension_type(s)
-
-    if check_scipy:
-        import scipy.sparse
-
-        assert not com.is_extension_type(scipy.sparse.bsr_matrix([1, 2, 3]))
-
-
-def test_is_extension_type_deprecation():
-    with tm.assert_produces_warning(FutureWarning):
-        com.is_extension_type([1, 2, 3])
-
-
 @pytest.mark.parametrize(
     "check_scipy", [False, pytest.param(True, marks=td.skip_if_no_scipy)]
 )