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fix: pyarrow clone returned same native object #2861

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fix: pyarrow clone returned same native object #2861

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49cfc15
fix: pyarrow clone returned same native object
FBruzzesi Jul 21, 2025
2774dda
handle arrow<14.0.0
FBruzzesi Jul 21, 2025
a78738e
Merge branch 'main' into fix/pyarrow-clone
FBruzzesi Jul 21, 2025
25e30a1
use combine chunks instead
FBruzzesi Jul 21, 2025
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9 changes: 8 additions & 1 deletion narwhals/_arrow/dataframe.py
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Original file line number Diff line number Diff line change
Expand Up @@ -591,7 +591,14 @@ def collect(
raise AssertionError(msg) # pragma: no cover

def clone(self) -> Self:
return self._with_native(self.native, validate_column_names=False)
native = self.native
if self._backend_version < (14, 0, 0):
cloned_table = pa.table(
{col: pa.array(native.column(col)) for col in native.column_names}
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@FBruzzesi FBruzzesi Jul 21, 2025 •
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Doing:

Suggested change
{col: pa.array(native.column(col)) for col in native.column_names}
{col: native.column(col) for col in native.column_names}

triggers the type-checker 😩

Argument of type "dict[str, ChunkedArray[Any]]" cannot be assigned to parameter "data" of type "Collection[ArrayOrChunkedArray[Any]] | DataFrame | SupportArrowArray | SupportArrowStream | SupportArrowDeviceArray" in function "table"

)
else:
cloned_table = pa.table(native)
return self._with_native(cloned_table, validate_column_names=False)

def item(self, row: int | None, column: int | str | None) -> Any:
from narwhals._arrow.series import maybe_extract_py_scalar
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1 change: 1 addition & 0 deletions tests/frame/clone_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ def test_clone(constructor_eager: ConstructorEager) -> None:
df_clone = df.clone()
assert df is not df_clone
assert df._compliant_frame is not df_clone._compliant_frame
assert df.to_native() is not df_clone.to_native()
assert_equal_data(df_clone, expected)
df_clone_mod = df_clone.with_columns((nw.col("a") + nw.col("b")).alias("c"))
assert_equal_data(df, expected)
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