BUG: Ensure series/frame mode() keeps int index #38732
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| if data.empty: | ||
| data.index = Index([], dtype="int64") | ||
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| return data |
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Empty result case doesn't hit algorithms.mode, so those changes aren't enough to ensure correct dtype
| df = DataFrame([], columns=["a", "b"]) | ||
| result = df.mode() | ||
| expected = DataFrame([], columns=["a", "b"], index=Index([], dtype="int64")) | ||
| tm.assert_frame_equal(result, expected) |
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Couldn't find any DataFrame.mode testing - guessing it relies on correctness from Series.mode() testing (in pandas/tests/test_algos.py::TestMode). However, empty result case doesn't hit Series.mode, so some DataFrame testing seems necessary. Is there a better place for this test?
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We keep them in pandas/tests/frame/test_reductions.py
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Ah thanks! Sorry for missing that
| df = DataFrame([], columns=["a", "b"]) | ||
| result = df.mode() | ||
| expected = DataFrame([], columns=["a", "b"], index=Index([], dtype="int64")) | ||
| tm.assert_frame_equal(result, expected) |
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We keep them in pandas/tests/frame/test_reductions.py
pandas/core/frame.py
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| data = data.apply(f, axis=axis) | ||
| # Ensure index is type stable (should always use int index) | ||
| if data.empty: | ||
| data.index = Index([], dtype="int64") |
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is this right for 32-bit machines?
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Changed to int, thanks for catching that
pandas/core/algorithms.py
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| @@ -954,7 +954,9 @@ def mode(values, dropna: bool = True) -> Series: | |||
| warn(f"Unable to sort modes: {err}") | |||
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| result = _reconstruct_data(result, original.dtype, original) | |||
| return Series(result) | |||
| # Ensure index is type stable (should always use int index) | |||
| index = None if len(result) else Index([], dtype=int) | |||
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these should use ibase.default_index instead of manual construction
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green |
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thanks @mzeitlin11 |
black pandasgit diff upstream/master -u -- "*.py" | flake8 --diff