DEPR: deprecate Index.is_categorical

doc/source/whatsnew/v2.0.0.rst

@@ -453,7 +453,7 @@ Other API changes
 
 Deprecations
 ~~~~~~~~~~~~
--
+- :meth:`Index.is_categorical` has been deprecated. Use :func:`pandas.api.types.is_categorical_dtype` instead (:issue:`50042`)
 
 .. ---------------------------------------------------------------------------
 

pandas/core/indexes/base.py

@@ -23,6 +23,7 @@
 
 import numpy as np
 
+
 from pandas._config import get_option
 
 from pandas._libs import (
@@ -2204,7 +2205,7 @@ def is_boolean(self) -> bool:
         is_floating : Check if the Index is a floating type.
         is_numeric : Check if the Index only consists of numeric data.
         is_object : Check if the Index is of the object dtype.
-        is_categorical : Check if the Index holds categorical data.
+        is_categorical : Check if the Index holds categorical data (deprecated).
         is_interval : Check if the Index holds Interval objects.
 
         Examples
@@ -2239,7 +2240,7 @@ def is_integer(self) -> bool:
         is_floating : Check if the Index is a floating type.
         is_numeric : Check if the Index only consists of numeric data.
         is_object : Check if the Index is of the object dtype.
-        is_categorical : Check if the Index holds categorical data.
+        is_categorical : Check if the Index holds categorical data (deprecated).
         is_interval : Check if the Index holds Interval objects.
 
         Examples
@@ -2278,7 +2279,7 @@ def is_floating(self) -> bool:
         is_integer : Check if the Index only consists of integers.
         is_numeric : Check if the Index only consists of numeric data.
         is_object : Check if the Index is of the object dtype.
-        is_categorical : Check if the Index holds categorical data.
+        is_categorical : Check if the Index holds categorical data (deprecated).
         is_interval : Check if the Index holds Interval objects.
 
         Examples
@@ -2317,7 +2318,7 @@ def is_numeric(self) -> bool:
         is_integer : Check if the Index only consists of integers.
         is_floating : Check if the Index is a floating type.
         is_object : Check if the Index is of the object dtype.
-        is_categorical : Check if the Index holds categorical data.
+        is_categorical : Check if the Index holds categorical data (deprecated).
         is_interval : Check if the Index holds Interval objects.
 
         Examples
@@ -2360,7 +2361,7 @@ def is_object(self) -> bool:
         is_integer : Check if the Index only consists of integers.
         is_floating : Check if the Index is a floating type.
         is_numeric : Check if the Index only consists of numeric data.
-        is_categorical : Check if the Index holds categorical data.
+        is_categorical : Check if the Index holds categorical data (deprecated).
         is_interval : Check if the Index holds Interval objects.
 
         Examples
@@ -2389,6 +2390,10 @@ def is_categorical(self) -> bool:
         """
         Check if the Index holds categorical data.
 
+        .. deprecated:: 2.0.0
+
+              Use `pandas.api.types.is_categorical_dtype` instead.
+
         Returns
         -------
         bool
@@ -2425,6 +2430,12 @@ def is_categorical(self) -> bool:
         >>> s.index.is_categorical()
         False
         """
+        warnings.warn(
+            f"{type(self).__name__}.is_categorical is deprecated."
+            "Use pandas.api.types.is_categorical_dtype instead",
+            FutureWarning,
+            stacklevel=find_stack_level(),
+        )
         return self.inferred_type in ["categorical"]
 
     @final
@@ -2445,7 +2456,7 @@ def is_interval(self) -> bool:
         is_floating : Check if the Index is a floating type.
         is_numeric : Check if the Index only consists of numeric data.
         is_object : Check if the Index is of the object dtype.
-        is_categorical : Check if the Index holds categorical data.
+        is_categorical : Check if the Index holds categorical data (deprecated).
 
         Examples
         --------

pandas/tests/indexes/common.py

@@ -795,6 +795,12 @@ def test_inv(self, simple_index):
             with pytest.raises(TypeError, match=msg):
                 ~Series(idx)
 
+    def test_is_categorical_is_deprecated(self, simple_index):
+        # GH50042
+        idx = simple_index
+        with tm.assert_produces_warning(FutureWarning):
+            idx.is_categorical()
+
 
 class NumericBase(Base):
     """