Resolving Index Resetting for tz_localize

doc/source/whatsnew/v1.3.3.rst

@@ -25,8 +25,8 @@ Fixed regressions
 
 Bug fixes
 ~~~~~~~~~
-- Bug in :meth:`.DataFrameGroupBy.agg` and :meth:`.DataFrameGroupBy.transform` with ``engine="numba"`` where ``index`` data was not being correctly passed into ``func`` (:issue:`43133`)
--
+- Bug in :meth:`.DataFrameGroupBy.agg` and :meth:`.DataFrameGroupBy.transform` with engine="numba" where index data was not being correctly passed into func (:issue:`43133`)
+- Fixed bug in :func:`__new__` of :class:`CombinedDatetimelikeProperties` maintains index of Categorical Datetime series (:issue:`43080`)
 
 .. ---------------------------------------------------------------------------
 

pandas/core/indexes/accessors.py

@@ -492,6 +492,7 @@ def __new__(cls, data: Series):
                 name=orig.name,
                 copy=False,
                 dtype=orig._values.categories.dtype,
+                index=orig.index,
             )
 
         if is_datetime64_dtype(data.dtype):

pandas/tests/series/methods/test_tz_localize.py

@@ -4,6 +4,7 @@
 from pandas._libs.tslibs import timezones
 
 from pandas import (
+    CategoricalDtype,
     DatetimeIndex,
     NaT,
     Series,
@@ -41,6 +42,23 @@ def test_series_tz_localize_ambiguous_bool(self):
         result = ser.dt.tz_localize("US/Central", ambiguous=[False])
         tm.assert_series_equal(result, expected1)
 
+    def test_series_tz_localize_matching_index(self):
+        # Matching the index of the result with that of the original series
+        # GH 43080
+        dt_series = Series(
+            date_range(start="2021-01-01T02:00:00", periods=5, freq="1D"),
+            index=[2, 6, 7, 8, 11],
+        )
+        cat_series = dt_series.astype(CategoricalDtype())
+        result = cat_series.dt.tz_localize("Europe/Berlin")
+        expected = Series(
+            date_range(
+                start="2021-01-01T02:00:00", periods=5, freq="1D", tz="Europe/Berlin"
+            ),
+            index=[2, 6, 7, 8, 11],
+        )
+        tm.assert_series_equal(result, expected)
+
     @pytest.mark.parametrize("tz", ["Europe/Warsaw", "dateutil/Europe/Warsaw"])
     @pytest.mark.parametrize(
         "method, exp",