Bug fix - rename dataframe reset index

doc/source/whatsnew/v1.5.0.rst

@@ -41,7 +41,7 @@ Other enhancements
 - Implemented a ``bool``-dtype :class:`Index`, passing a bool-dtype array-like to ``pd.Index`` will now retain ``bool`` dtype instead of casting to ``object`` (:issue:`45061`)
 - Implemented a complex-dtype :class:`Index`, passing a complex-dtype array-like to ``pd.Index`` will now retain complex dtype instead of casting to ``object`` (:issue:`45845`)
 - :class:`Series` and :class:`DataFrame` with ``IntegerDtype`` now supports bitwise operations (:issue:`34463`)
--
+- :meth:`DataFrame.reset_index` now accepts a ``names`` argument which renames the index names (:issue:`6878`)
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_150.notable_bug_fixes:

pandas/core/frame.py

@@ -5625,6 +5625,7 @@ def reset_index(
         col_level: Hashable = ...,
         col_fill: Hashable = ...,
         allow_duplicates: bool | lib.NoDefault = ...,
+        names: Hashable | Sequence[Hashable] = None,
     ) -> DataFrame:
         ...
 
@@ -5637,6 +5638,7 @@ def reset_index(
         col_level: Hashable = ...,
         col_fill: Hashable = ...,
         allow_duplicates: bool | lib.NoDefault = ...,
+        names: Hashable | Sequence[Hashable] = None,
     ) -> None:
         ...
 
@@ -5649,6 +5651,7 @@ def reset_index(
         col_level: Hashable = ...,
         col_fill: Hashable = ...,
         allow_duplicates: bool | lib.NoDefault = ...,
+        names: Hashable | Sequence[Hashable] = None,
     ) -> None:
         ...
 
@@ -5661,6 +5664,7 @@ def reset_index(
         col_level: Hashable = ...,
         col_fill: Hashable = ...,
         allow_duplicates: bool | lib.NoDefault = ...,
+        names: Hashable | Sequence[Hashable] = None,
     ) -> None:
         ...
 
@@ -5672,6 +5676,7 @@ def reset_index(
         col_level: Hashable = ...,
         col_fill: Hashable = ...,
         allow_duplicates: bool | lib.NoDefault = ...,
+        names: Hashable | Sequence[Hashable] = None,
     ) -> None:
         ...
 
@@ -5684,6 +5689,7 @@ def reset_index(
         col_level: Hashable = ...,
         col_fill: Hashable = ...,
         allow_duplicates: bool | lib.NoDefault = ...,
+        names: Hashable | Sequence[Hashable] = None,
     ) -> DataFrame | None:
         ...
 
@@ -5696,6 +5702,7 @@ def reset_index(
         col_level: Hashable = 0,
         col_fill: Hashable = "",
         allow_duplicates: bool | lib.NoDefault = lib.no_default,
+        names: Hashable | Sequence[Hashable] = None,
     ) -> DataFrame | None:
         """
         Reset the index, or a level of it.
@@ -5723,6 +5730,10 @@ def reset_index(
             levels are named. If None then the index name is repeated.
         allow_duplicates : bool, optional, default lib.no_default
             Allow duplicate column labels to be created.
+        names : str, tuple or list, default None
+            Using the given string, rename the DataFrame column which contains the
+            index data. If the DataFrame has a MultiIndex, this has to be a list or
+            tuple with length equal to the number of levels.
 
             .. versionadded:: 1.5.0
 
@@ -5841,6 +5852,15 @@ class    max    type
         parrot           bird   24.0     fly
         lion           mammal   80.5     run
         monkey         mammal    NaN    jump
+
+        Using the `names` parameter, choose a name for the index column:
+
+        >>> df.reset_index(names='name')
+            name   class  max_speed
+        0  falcon    bird      389.0
+        1  parrot    bird       24.0
+        2    lion  mammal       80.5
+        3  monkey  mammal        NaN
         """
         inplace = validate_bool_kwarg(inplace, "inplace")
         self._check_inplace_and_allows_duplicate_labels(inplace)
@@ -5861,12 +5881,12 @@ class    max    type
 
         if not drop:
             to_insert: Iterable[tuple[Any, Any | None]]
+
+            default = "index" if "index" not in self else "level_0"
+            names = self.index.get_default_index_names(names, default)
             if isinstance(self.index, MultiIndex):
-                names = com.fill_missing_names(self.index.names)
                 to_insert = zip(self.index.levels, self.index.codes)
             else:
-                default = "index" if "index" not in self else "level_0"
-                names = [default] if self.index.name is None else [self.index.name]
                 to_insert = ((self.index, None),)
 
             multi_col = isinstance(self.columns, MultiIndex)

pandas/core/indexes/base.py

@@ -1765,6 +1765,29 @@ def _validate_names(
 
         return new_names
 
+    def get_default_index_names(self, names=None, default=None) -> Sequence[str]:
+        from pandas.core.indexes.multi import MultiIndex
+
+        # if names is not None and not all(isinstance(name, str) for name in names):
+        #    raise ValueError("Names must be a string")
+        if names is not None:
+            if isinstance(names, str):
+                names = [names]
+            elif isinstance(names, list) and not all(
+                isinstance(name, str) for name in names
+            ):
+                raise ValueError("Names must be a string")
+            elif not (isinstance(names, list) and not isinstance(names, str)):
+                raise ValueError("Names must be a string or list")
+
+        if not names:
+            if isinstance(self, MultiIndex):
+                names = com.fill_missing_names(self.names)
+            else:
+                names = [default] if self.name is None else [self.name]
+
+        return names
+
     def _get_names(self) -> FrozenList:
         return FrozenList((self.name,))
 

pandas/tests/frame/methods/test_reset_index.py

@@ -754,3 +754,30 @@ def test_reset_index_interval_columns_object_cast():
         columns=Index(["Year", Interval(0, 1), Interval(1, 2)]),
     )
     tm.assert_frame_equal(result, expected)
+
+
+def test_reset_index_rename(float_frame):
+    # GH 6878
+    result = float_frame.reset_index(names="new_name")
+    expected = Series(float_frame.index.values, name="new_name")
+    tm.assert_series_equal(result["new_name"], expected)
+
+    with pytest.raises(ValueError, match="Names must be a string"):
+        float_frame.reset_index(names=1)
+
+
+def test_reset_index_rename_multiindex(float_frame):
+    # GH 6878
+    stacked_df = float_frame.stack()[::2]
+    stacked_df = DataFrame({"foo": stacked_df, "bar": stacked_df})
+
+    names = ["first", "second"]
+    stacked_df.index.names = names
+
+    result = stacked_df.reset_index()
+    expected = stacked_df.reset_index(names=["new_first", "new_second"])
+    tm.assert_series_equal(result["first"], expected["new_first"], check_names=False)
+    tm.assert_series_equal(result["second"], expected["new_second"], check_names=False)
+
+    with pytest.raises(ValueError, match="Names must be a string or list"):
+        stacked_df.reset_index(names={"first": "new_first", "second": "new_second"})