from_product

Author: twoertwein

pandas/core/generic.py

@@ -1050,7 +1050,9 @@ def _rename(
             return result.__finalize__(self, method="rename")
 
     @rewrite_axis_style_signature("mapper", [("copy", True), ("inplace", False)])
-    def rename_axis(self, mapper: IndexLabel = lib.no_default, **kwargs):
+    def rename_axis(
+        self, mapper: IndexLabel | lib.NoDefault = lib.no_default, **kwargs
+    ):
         """
         Set the name of the axis for the index or columns.
 

pandas/core/groupby/groupby.py

@@ -4050,12 +4050,7 @@ def _reindex_output(
             # "ndarray[Any, dtype[floating[_64Bit]]]"; expected "Index"
             levels_list.append(qs)  # type: ignore[arg-type]
             names = names + [None]
-        # error: Argument "names" to "from_product" of "MultiIndex" has
-        # incompatible type "List[Hashable]"; expected "Union[Sequence[
-        # Optional[str]], Literal[_NoDefault.no_default]]"
-        index, _ = MultiIndex.from_product(
-            levels_list, names=names  # type: ignore[arg-type]
-        ).sortlevel()
+        index, _ = MultiIndex.from_product(levels_list, names=names).sortlevel()
 
         if self.as_index:
             # Always holds for SeriesGroupBy unless GH#36507 is implemented

pandas/core/indexes/multi.py

@@ -581,7 +581,7 @@ def from_product(
         cls,
         iterables: Sequence[Iterable[Hashable]],
         sortorder: int | None = None,
-        names: Sequence[str | None] | lib.NoDefault = lib.no_default,
+        names: Sequence[Hashable] | lib.NoDefault = lib.no_default,
     ) -> MultiIndex:
         """
         Make a MultiIndex from the cartesian product of multiple iterables.