Revert "Shift to adding frequency to shallow copy of DatetimeIndex instead of modifying take function"

This reverts commit 02c2f95.

Author: annika-rudolph

pandas/core/arrays/datetimelike.py

@@ -66,6 +66,7 @@
     ScalarIndexer,
     Self,
     SequenceIndexer,
+    TakeIndexer,
     TimeAmbiguous,
     TimeNonexistent,
     npt,
@@ -2364,6 +2365,27 @@ def interpolate(
             return self
         return type(self)._simple_new(out_data, dtype=self.dtype)
 
+    def take(
+        self,
+        indices: TakeIndexer,
+        *,
+        allow_fill: bool = False,
+        fill_value: Any = None,
+        axis: AxisInt = 0,
+    ) -> Self:
+        result = super().take(
+            indices=indices, allow_fill=allow_fill, fill_value=fill_value, axis=axis
+        )
+
+        indices = np.asarray(indices, dtype=np.intp)
+        maybe_slice = lib.maybe_indices_to_slice(indices, len(self))
+
+        if isinstance(maybe_slice, slice):
+            freq = self._get_getitem_freq(maybe_slice)
+            result.freq = freq
+
+        return result
+
     # --------------------------------------------------------------
     # Unsorted
 

pandas/core/indexes/base.py

@@ -748,7 +748,7 @@ def _format_duplicate_message(self) -> DataFrame:
     # --------------------------------------------------------------------
     # Index Internals Methods
 
-    def _shallow_copy(self, values, name: Hashable = no_default, **kwargs) -> Self:
+    def _shallow_copy(self, values, name: Hashable = no_default) -> Self:
         """
         Create a new Index with the same class as the caller, don't copy the
         data, use the same object attributes with passed in attributes taking

pandas/core/indexes/datetimelike.py

@@ -22,7 +22,6 @@
     Timedelta,
     lib,
 )
-from pandas._libs.lib import no_default
 from pandas._libs.tslibs import (
     BaseOffset,
     Resolution,
@@ -69,10 +68,7 @@
 from pandas.core.tools.timedeltas import to_timedelta
 
 if TYPE_CHECKING:
-    from collections.abc import (
-        Hashable,
-        Sequence,
-    )
+    from collections.abc import Sequence
     from datetime import datetime
 
     from pandas._typing import (
@@ -842,20 +838,3 @@ def take(
             freq = self._data._get_getitem_freq(maybe_slice)
             result._data._freq = freq
         return result
-
-    @doc(Index._shallow_copy)
-    def _shallow_copy( # type: ignore[override]
-        self,
-        values,
-        name: Hashable = no_default,
-        level_codes=no_default,
-    ) -> Self:
-        name = self._name if name is no_default else name
-        result = self._simple_new(values, name=name, refs=self._references)
-        if level_codes is not no_default:
-            indices = np.asarray(level_codes, dtype=np.intp)
-            maybe_slice = lib.maybe_indices_to_slice(indices, len(values))
-            if isinstance(maybe_slice, slice):
-                freq = self._data._get_getitem_freq(maybe_slice)
-                result._data._freq = freq
-        return result

pandas/core/indexes/multi.py

@@ -1244,9 +1244,7 @@ def _constructor(self) -> Callable[..., MultiIndex]:  # type: ignore[override]
         return type(self).from_tuples
 
     @doc(Index._shallow_copy)
-    def _shallow_copy(
-        self, values: np.ndarray, name=lib.no_default, **kwargs
-    ) -> MultiIndex:
+    def _shallow_copy(self, values: np.ndarray, name=lib.no_default) -> MultiIndex:
         names = name if name is not lib.no_default else self.names
 
         return type(self).from_tuples(values, sortorder=None, names=names)
@@ -1716,7 +1714,7 @@ def _get_level_values(self, level: int, unique: bool = False) -> Index:
         if unique:
             level_codes = algos.unique(level_codes)
         filled = algos.take_nd(lev._values, level_codes, fill_value=lev._na_value)
-        return lev._shallow_copy(filled, name=name, level_codes=level_codes)
+        return lev._shallow_copy(filled, name=name)
 
     # error: Signature of "get_level_values" incompatible with supertype "Index"
     def get_level_values(self, level) -> Index:  # type: ignore[override]

pandas/core/indexes/range.py

@@ -472,7 +472,7 @@ def __iter__(self) -> Iterator[int]:
         yield from self._range
 
     @doc(Index._shallow_copy)
-    def _shallow_copy(self, values, name: Hashable = no_default, **kwargs):
+    def _shallow_copy(self, values, name: Hashable = no_default):
         name = self._name if name is no_default else name
 
         if values.dtype.kind == "f":

pandas/tests/indexes/multi/test_get_level_values.py

@@ -126,7 +126,9 @@ def test_values_loses_freq_of_underlying_index():
 
 def test_get_level_values_gets_frequency_correctly():
     # GH#57949 GH#58327
-    datetime_index = date_range(start=pd.to_datetime("1/1/2018"), periods=4, freq="YS")
+    datetime_index = pd.date_range(
+        start=pd.to_datetime("1/1/2018"), periods=4, freq="YS"
+    )
     other_index = ["A"]
     multi_index = MultiIndex.from_product([datetime_index, other_index])