Skip to content

BUG: transpose not respecting CoW #51430

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
phofl merged 9 commits into from
Feb 22, 2023
Merged

BUG: transpose not respecting CoW #51430

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
9 commits
Select commit Hold shift + click to select a range
138df12
BUG: transpose not respecting CoW
phofl Feb 16, 2023
29c1bda
FIx
phofl Feb 16, 2023
001ddac
Merge branch 'main' into cow_transpose
phofl Feb 16, 2023
f0336da
Merge remote-tracking branch 'upstream/main' into cow_transpose
phofl Feb 17, 2023
ffcd4c0
Adjust
phofl Feb 17, 2023
d305e42
Merge remote-tracking branch 'upstream/main' into cow_transpose
phofl Feb 20, 2023
530f00c
Fix ci
phofl Feb 20, 2023
742e54c
Fix array manager
phofl Feb 20, 2023
bdbc286
Merge branch 'main' into cow_transpose
phofl Feb 21, 2023
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
Adjust
  • Loading branch information
@phofl
phofl committed Feb 17, 2023
commit ffcd4c055a04dbb9e9c2b4a4aa755b50b1ae57cc
9 changes: 3 additions & 6 deletions pandas/core/frame.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -3557,17 +3557,14 @@ def transpose(self, *args, copy: bool = False) -> DataFrame:
if self._can_fast_transpose:
# Note: tests pass without this, but this improves perf quite a bit.
new_vals = self._values.T
if copy:
if copy and not using_copy_on_write():
new_vals = new_vals.copy()

result = self._constructor(
new_vals, index=self.columns, columns=self.index, copy=False
)
if using_copy_on_write() and not copy and len(self) > 0:
result._mgr.blocks[0].refs = self._mgr.blocks[0].refs # type: ignore[union-attr] # noqa
result._mgr.blocks[0].refs.add_reference( # type: ignore[union-attr]
result._mgr.blocks[0] # type: ignore[arg-type, union-attr]
)
if using_copy_on_write() and len(self) > 0:
result._mgr.add_references(self._mgr) # type: ignore[arg-type]

elif (
self._is_homogeneous_type and dtypes and is_extension_array_dtype(dtypes[0])
Expand Down
11 changes: 8 additions & 3 deletions pandas/tests/copy_view/test_methods.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1595,12 +1595,17 @@ def test_inplace_arithmetic_series_with_reference(using_copy_on_write):
assert np.shares_memory(get_array(ser), get_array(view))


def test_transpose(using_copy_on_write):
@pytest.mark.parametrize("copy", [True, False])
def test_transpose(using_copy_on_write, copy):
df = DataFrame({"a": [1, 2, 3], "b": 1})
df_orig = df.copy()
result = df.T
result = df.transpose(copy=copy)

if not copy or using_copy_on_write:
assert np.shares_memory(get_array(df, "a"), get_array(result, 0))
else:
assert not np.shares_memory(get_array(df, "a"), get_array(result, 0))

assert np.shares_memory(get_array(df, "a"), get_array(result, 0))
result.iloc[0, 0] = 100
if using_copy_on_write:
tm.assert_frame_equal(df, df_orig)
Expand Down