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BUG: Fix segfault in Categorical.set_categories #24680

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Merged
merged 1 commit into from
Jan 9, 2019
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BUG: Fix segfault in Categorical.set_categories #24680

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1 change: 1 addition & 0 deletions doc/source/whatsnew/v0.24.0.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -1501,6 +1501,7 @@ Categorical
- Bug in :meth:`Series.where` losing the categorical dtype for categorical data (:issue:`24077`)
- Bug in :meth:`Categorical.apply` where ``NaN`` values could be handled unpredictably. They now remain unchanged (:issue:`24241`)
- Bug in :class:`Categorical` comparison methods incorrectly raising ``ValueError`` when operating against a :class:`DataFrame` (:issue:`24630`)
- Bug in :meth:`Categorical.set_categories` where setting fewer new categories with ``rename=True`` caused a segmentation fault (:issue:`24675`)

Datetimelike
^^^^^^^^^^^^
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4 changes: 2 additions & 2 deletions pandas/core/arrays/categorical.py
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Expand Up @@ -852,9 +852,9 @@ def set_categories(self, new_categories, ordered=None, rename=False,
if (cat.dtype.categories is not None and
len(new_dtype.categories) < len(cat.dtype.categories)):
# remove all _codes which are larger and set to -1/NaN
self._codes[self._codes >= len(new_dtype.categories)] = -1
cat._codes[cat._codes >= len(new_dtype.categories)] = -1
else:
codes = _recode_for_categories(self.codes, self.categories,
codes = _recode_for_categories(cat.codes, cat.categories,
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@jschendel jschendel Jan 9, 2019 •
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This change shouldn't alter existing behavior, as self and cat should be identical within this branch of the if/else. More so a defensive future-proofing change in case future modifications cause a divergence between self and cat prior to this. All operations at this point should be in relation to cat anyways, as that's the object we'll be returning.

new_dtype.categories)
cat._codes = codes
cat._dtype = new_dtype
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7 changes: 7 additions & 0 deletions pandas/tests/arrays/categorical/test_api.py
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Expand Up @@ -310,6 +310,13 @@ def test_set_categories_many(self, values, categories, new_categories,
result = c.set_categories(new_categories, ordered=ordered)
tm.assert_categorical_equal(result, expected)

def test_set_categories_rename_less(self):
# GH 24675
cat = Categorical(['A', 'B'])
result = cat.set_categories(['A'], rename=True)
expected = Categorical(['A', np.nan])
tm.assert_categorical_equal(result, expected)

def test_set_categories_private(self):
cat = Categorical(['a', 'b', 'c'], categories=['a', 'b', 'c', 'd'])
cat._set_categories(['a', 'c', 'd', 'e'])
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