try rename with copy=True

Maybe addresses (#2680 (comment))

Author: dangotbanned

narwhals/_pandas_like/dataframe.py

@@ -459,10 +459,15 @@ def with_columns(self, *exprs: PandasLikeExpr) -> Self:
         df.columns.name = self.native.columns.name
         return self._with_native(df, validate_column_names=False)
 
-    def rename(self, mapping: Mapping[str, str]) -> Self:
+    def rename(self, mapping: Mapping[str, str], *, copy: bool = False) -> Self:
         if mapping:
             return self._with_native(
-                rename(self.native, columns=mapping, implementation=self._implementation)
+                rename(
+                    self.native,
+                    columns=mapping,
+                    implementation=self._implementation,
+                    copy=copy,
+                )
             )
         return self._with_native(self.native, validate_column_names=False)
 

narwhals/_pandas_like/group_by.py

@@ -4,7 +4,7 @@
 from functools import lru_cache
 from itertools import chain
 from operator import methodcaller
-from typing import TYPE_CHECKING, Any, ClassVar, Literal, overload
+from typing import TYPE_CHECKING, Any, ClassVar, Literal, cast, overload
 
 from narwhals._compliant import EagerGroupBy
 from narwhals._expression_parsing import evaluate_output_names_and_aliases
@@ -255,7 +255,9 @@ def __init__(
         frame, self._keys, self._output_key_names = self._parse_keys(df, keys=keys)
         self._exclude: tuple[str, ...] = (*self._keys, *self._output_key_names)
         self._remap_non_str_columns = _remap_non_str(self)
-        self._compliant_frame = frame.rename(self._remap_non_str_columns)
+        self._compliant_frame = cast("PandasLikeDataFrame", frame).rename(
+            self._remap_non_str_columns, copy=True
+        )
         # Drop index to avoid potential collisions:
         # https://github.com/narwhals-dev/narwhals/issues/1907.
         native = self.compliant.native

narwhals/_pandas_like/utils.py

@@ -182,14 +182,18 @@ def set_index(
 
 
 def rename(
-    obj: NativeNDFrameT, *args: Any, implementation: Implementation, **kwargs: Any
+    obj: NativeNDFrameT,
+    *args: Any,
+    implementation: Implementation,
+    copy: bool = False,
+    **kwargs: Any,
 ) -> NativeNDFrameT:
     """Wrapper around pandas' rename so that we can set `copy` based on implementation/version."""
     if implementation is Implementation.PANDAS and (
         implementation._backend_version() >= (3,)
     ):  # pragma: no cover
         return obj.rename(*args, **kwargs, inplace=False)
-    return obj.rename(*args, **kwargs, copy=False, inplace=False)
+    return obj.rename(*args, **kwargs, copy=copy, inplace=False)
 
 
 @functools.lru_cache(maxsize=16)