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REF: deduplicate group min/max #40584

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Merged
merged 2 commits into from
Mar 23, 2021
Merged

REF: deduplicate group min/max #40584

merged 2 commits into from
Mar 23, 2021

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mzeitlin11
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ASVs look unaffected:

before           after         ratio
     [05a0e98a]       [16d06e22]
     <master>         <ref/deduplicate_grp_min_max>
         33.0±3ms         33.3±1ms     1.01  gil.ParallelGroupbyMethods.time_loop(2, 'max')
       32.2±0.4ms         34.5±3ms     1.07  gil.ParallelGroupbyMethods.time_loop(2, 'min')
         64.1±1ms       65.6±0.5ms     1.02  gil.ParallelGroupbyMethods.time_loop(4, 'max')
         65.3±3ms         65.5±1ms     1.00  gil.ParallelGroupbyMethods.time_loop(4, 'min')
         20.2±2ms       20.2±0.8ms     1.00  gil.ParallelGroupbyMethods.time_parallel(2, 'max')
         21.3±1ms       20.1±0.8ms     0.95  gil.ParallelGroupbyMethods.time_parallel(2, 'min')
       25.1±0.7ms       25.3±0.5ms     1.01  gil.ParallelGroupbyMethods.time_parallel(4, 'max')
       25.0±0.4ms         26.5±2ms     1.06  gil.ParallelGroupbyMethods.time_parallel(4, 'min')
         125±50ms          104±1ms    ~0.83  groupby.GroupByCythonAgg.time_frame_agg('float64', 'max')
          105±2ms          107±2ms     1.02  groupby.GroupByCythonAgg.time_frame_agg('float64', 'min')

mzeitlin11
mzeitlin11 commented Mar 23, 2021
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pandas/_libs/groupby.pyx
group_min_or_max[lab, j] = val
else:
if val < group_min_or_max[lab, j]:
group_min_or_max[lab, j] = val
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Wanted to be able to do something like if PyObject_RichCompareBool(val, ..., cmp_method): ... to simplify the conditional logic, but couldn't find a way to do something like this in Cython without the GIL.

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is there a perf impact here? its checking compute_max at each step in a nested loop

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@mzeitlin11 mzeitlin11 Mar 23, 2021 •
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I didn't see any perf impact based on ASVs above. For a loop invariant like compute_max, I'd guess this check is optimized away by the compiler. (It could also just be negligible compared to the cost of the indexing operations)

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makes sense. worth it to de-duplicate a bunch of code.

@mzeitlin11 mzeitlin11 added Algos Non-arithmetic algos: value_counts, factorize, sorting, isin, clip, shift, diff Groupby Refactor Internal refactoring of code labels Mar 23, 2021
@jreback jreback added this to the 1.3 milestone Mar 23, 2021
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jreback approved these changes Mar 23, 2021
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lgtm. @jbrockmendel if any comments

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LGTM

@jreback jreback merged commit 6ed2fe8 into pandas-dev:master Mar 23, 2021
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jreback commented Mar 23, 2021

thanks @mzeitlin11

@mzeitlin11 mzeitlin11 deleted the ref/deduplicate_grp_min_max branch March 23, 2021 20:31
@mzeitlin11 mzeitlin11 mentioned this pull request Mar 23, 2021
Merged
vladu pushed a commit to vladu/pandas that referenced this pull request Apr 5, 2021
@mzeitlin11 @vladu
REF: deduplicate group min/max (pandas-dev#40584)
5dc783d
JulianWgs pushed a commit to JulianWgs/pandas that referenced this pull request Jul 3, 2021
@mzeitlin11 @JulianWgs
REF: deduplicate group min/max (pandas-dev#40584)
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Algos Non-arithmetic algos: value_counts, factorize, sorting, isin, clip, shift, diff Groupby Refactor Internal refactoring of code
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