fix(utils): make is_sorted_nb reject NaN to match is_sorted (closes #868) - #870
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caiyi0616 wants to merge 1 commit into
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fix(utils): make is_sorted_nb reject NaN to match is_sorted (closes #868)#870caiyi0616 wants to merge 1 commit into
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Fixes polakowo#868 - is_sorted_nb incorrectly reported arrays with NaN values as sorted because `NaN < x` and `x < NaN` both return False in Numba, causing the loop to never return False for NaN-adjacent pairs. The fix adds explicit NaN checks via math.isnan() before the comparison, matching the non-Numba behavior where np.all(a[:-1] <= a[1:]) returns False when any adjacent pair involves NaN (since NaN <= NaN is False). Added 14 regression assertions covering: NaN in middle, NaN at start, adjacent NaN pairs, and single-NaN edge case (no adjacent pair = sorted). Note: Numba does not support np.isnan on scalars in object mode, so math.isnan() (from the math module) is used instead.
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Summary
is_sorted_nbreject unordered adjacent comparisons, matchingis_sortedwhen an array containsNaNPreviously,
<returned false for aNaNpair and the Numba implementationcould incorrectly report the array as sorted.
Root cause
NaN < xandx < NaNboth returnFalsein Numba, so the loop bodynever executed
return Falsefor adjacent NaN pairs, incorrectly treatingNaN-containing arrays as sorted.
Fix
Added explicit
math.isnan()checks before the<comparison, matching thenon-Numba behavior where
np.all(a[:-1] <= a[1:])returnsFalsewhen anyadjacent pair involves NaN (since
NaN <= NaNisFalse).Testing
pytest tests/test_utils.py -k is_sorted -v-> PASSEDtest_utils.pycontinue to passadjacent NaN pairs, and single-NaN edge case (no adjacent pair = sorted)
Changes
vectorbt/utils/array_.py: addedimport math; updated docstring;replaced single-line
if a[i+1] < a[i]with explicit NaN checktests/test_utils.py: added 14 NaN regression assertions