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PERF improve performance of is_lexsorted #47459

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Merged
merged 3 commits into from
Jun 24, 2022
Merged

PERF improve performance of is_lexsorted #47459

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4a7920c
improve performance of is_lexsorted
MarcoGorelli Jun 22, 2022
8976351
early return
MarcoGorelli Jun 23, 2022
01d2d18
undo early return
MarcoGorelli Jun 23, 2022
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1 change: 1 addition & 0 deletions doc/source/whatsnew/v1.5.0.rst
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Expand Up @@ -739,6 +739,7 @@ Performance improvements
- Performance improvement in :func:`factorize` (:issue:`46109`)
- Performance improvement in :class:`DataFrame` and :class:`Series` constructors for extension dtype scalars (:issue:`45854`)
- Performance improvement in :func:`read_excel` when ``nrows`` argument provided (:issue:`32727`)
- Performance improvement in :meth:`MultiIndex.is_monotonic_increasing` (:issue:`47458`)

.. ---------------------------------------------------------------------------
.. _whatsnew_150.bug_fixes:
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2 changes: 2 additions & 0 deletions pandas/_libs/algos.pyx
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Expand Up @@ -180,6 +180,8 @@ def is_lexsorted(list_of_arrays: list) -> bint:
else:
result = False
break
if not result:
break
Comment on lines 181 to +184
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This makes sense to me. But probably even better instead of the double break, to simply return when we know it's False. And we don't even need the result variable, since the return at the end of the function should always be return True.

Suggested change
result = False
break
if not result:
break
free(vecs)
return False

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looks like this isn't allowed

Error compiling Cython file:
------------------------------------------------------------
...
                else:
                    result = False
                    break
            if not result:
                free(vecs)
                return False
               ^
------------------------------------------------------------
pandas/_libs/algos.pyx:184:16: Returning Python object not allowed without gil

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Good to know, I was wondering if there was a Cython limitation. Thanks for trying it.

free(vecs)
return result

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