Revert "ENH: set_index copy kwd (pandas-dev#48043)"

This reverts commit 9716fcb.

Author: jorisvandenbossche

doc/source/whatsnew/v1.5.0.rst

@@ -329,8 +329,8 @@ Other enhancements
 - :meth:`DataFrame.quantile` gained a ``method`` argument that can accept ``table`` to evaluate multi-column quantiles (:issue:`43881`)
 - :class:`Interval` now supports checking whether one interval is contained by another interval (:issue:`46613`)
 - Added ``copy`` keyword to :meth:`Series.set_axis` and :meth:`DataFrame.set_axis` to allow user to set axis on a new object without necessarily copying the underlying data (:issue:`47932`)
-- :meth:`DataFrame.set_index` now supports a ``copy`` keyword. If ``False``, the underlying data is not copied when a new :class:`DataFrame` is returned (:issue:`48043`)
 - The method :meth:`.ExtensionArray.factorize` accepts ``use_na_sentinel=False`` for determining how null values are to be treated (:issue:`46601`)
+- :meth:`Series.add_suffix`, :meth:`DataFrame.add_suffix`, :meth:`Series.add_prefix` and :meth:`DataFrame.add_prefix` support a ``copy`` argument. If ``False``, the underlying data is not copied in the returned object (:issue:`47934`)
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_150.notable_bug_fixes:

pandas/core/frame.py

@@ -5858,7 +5858,6 @@ def set_index(
         append: bool = ...,
         inplace: Literal[False] = ...,
         verify_integrity: bool = ...,
-        copy: bool | lib.NoDefault = ...,
     ) -> DataFrame:
         ...
 
@@ -5871,7 +5870,6 @@ def set_index(
         append: bool = ...,
         inplace: Literal[True],
         verify_integrity: bool = ...,
-        copy: bool | lib.NoDefault = ...,
     ) -> None:
         ...
 
@@ -5883,7 +5881,6 @@ def set_index(
         append: bool = False,
         inplace: bool = False,
         verify_integrity: bool = False,
-        copy: bool | lib.NoDefault = lib.no_default,
     ) -> DataFrame | None:
         """
         Set the DataFrame index using existing columns.
@@ -5910,11 +5907,6 @@ def set_index(
             Check the new index for duplicates. Otherwise defer the check until
             necessary. Setting to False will improve the performance of this
             method.
-        copy : bool, default True
-            Whether to make a copy of the underlying data when returning a new
-            DataFrame.
-
-            .. versionadded:: 1.5.0
 
         Returns
         -------
@@ -5980,13 +5972,6 @@ def set_index(
         4 16     10  2014    31
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
-        if inplace:
-            if copy is not lib.no_default:
-                raise ValueError("Cannot specify copy when inplace=True")
-            copy = False
-        elif copy is lib.no_default:
-            copy = True
-
         self._check_inplace_and_allows_duplicate_labels(inplace)
         if not isinstance(keys, list):
             keys = [keys]
@@ -6022,7 +6007,7 @@ def set_index(
         if inplace:
             frame = self
         else:
-            frame = self.copy(deep=copy)
+            frame = self.copy()
 
         arrays = []
         names: list[Hashable] = []

pandas/tests/frame/methods/test_set_index.py

@@ -25,25 +25,6 @@
 
 
 class TestSetIndex:
-    def test_set_index_copy(self):
-        # GH#48043
-        df = DataFrame({"A": [1, 2], "B": [3, 4], "C": [5, 6]})
-        expected = DataFrame({"B": [3, 4], "C": [5, 6]}, index=Index([1, 2], name="A"))
-
-        res = df.set_index("A", copy=True)
-        tm.assert_frame_equal(res, expected)
-        assert not any(tm.shares_memory(df[col], res[col]) for col in res.columns)
-
-        res = df.set_index("A", copy=False)
-        tm.assert_frame_equal(res, expected)
-        assert all(tm.shares_memory(df[col], res[col]) for col in res.columns)
-
-        msg = "Cannot specify copy when inplace=True"
-        with pytest.raises(ValueError, match=msg):
-            df.set_index("A", inplace=True, copy=True)
-        with pytest.raises(ValueError, match=msg):
-            df.set_index("A", inplace=True, copy=False)
-
     def test_set_index_multiindex(self):
         # segfault in GH#3308
         d = {"t1": [2, 2.5, 3], "t2": [4, 5, 6]}