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BUG: empty slice assignment raises if datetime column is present #50942 #62934

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Merged
merged 8 commits into from
Nov 7, 2025
+19 −0
Merged

BUG: empty slice assignment raises if datetime column is present #50942 #62934

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3c1ae7b
add test for issue #50942
litang99 Oct 31, 2025
a44af1a
merge with main
litang99 Nov 4, 2025
c997161
address PR comment: construct DaataFrame in the body of test
litang99 Nov 4, 2025
8d920f1
address PR comment: add assert_frame_equal
litang99 Nov 4, 2025
d765395
merged wth main
litang99 Nov 4, 2025
31c75b2
Merge branch 'main' into indexs_50942
litang99 Nov 5, 2025
f66749d
Merge branch 'main' into indexs_50942
litang99 Nov 7, 2025
4aedae4
address PR comment: assert df equals to expected
litang99 Nov 7, 2025
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21 changes: 21 additions & 0 deletions pandas/tests/indexing/test_loc.py
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Original file line number Diff line number Diff line change
Expand Up @@ -258,6 +258,27 @@ def test_loc_getitem_single_boolean_arg(self, obj, key, exp):
else:
assert res == exp

@pytest.mark.parametrize(
"data",
[
[datetime(2025, 10, 30)],
[Timestamp(2025, 10, 30)] * 2,
[Timedelta(1)],
[Timedelta(1), Timedelta(2)],
],
)
def test_loc_empty_slice_assignment_with_datetime(self, data):
# issue #50942
# empty slice assignment with datetime or timedelta should not raise exceptions
mask = [False] * len(data)
try:
df = DataFrame(data=data, columns=["A"])
res = df.loc[mask]
res = df
tm.assert_frame_equal(res, df)
except Exception:
pytest.fail("loc empty slice assignment raised Exception unexpectedly!")
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@mroeschke mroeschke Nov 4, 2025

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  1. You can remove the try/except
  2. In the original issue, it's testing a setitem, so this would need to be
expected = df.copy()
df.loc[mask] = df
tm.assert_frame_equal(df, expected)

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@litang99 litang99 Nov 7, 2025

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updated



class TestLocBaseIndependent:
# Tests for loc that do not depend on subclassing Base
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