[jira] [Created] (ARROW-11568) [C++][Compute] Mode kernel performance is bad in some conditions

["Yibo Cai (Jira)" <ji...@apache.org>]

Yibo Cai created ARROW-11568:
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             Summary: [C++][Compute] Mode kernel performance is bad in some conditions
                 Key: ARROW-11568
                 URL: https://issues.apache.org/jira/browse/ARROW-11568
             Project: Apache Arrow
          Issue Type: Improvement
          Components: C++
            Reporter: Yibo Cai
            Assignee: Yibo Cai


Comparing with scipy.stats.mode, arrow mode kernel is much slower in some conditions. See below example.

{noformat}
In [1]: import numpy as np

In [2]: import scipy.stats

In [3]: import pyarrow.compute as pc

In [4]: f = np.random.rand(12345678)

In [5]: time scipy.stats.mode(f)
CPU times: user 1.14 s, sys: 111 ms, total: 1.25 s
Wall time: 1.25 s
Out[5]: ModeResult(mode=array([2.25710692e-08]), count=array([1]))

In [6]: time pc.mode(f)[0]
CPU times: user 8.44 s, sys: 338 ms, total: 8.77 s
Wall time: 8.77 s
Out[6]: <pyarrow.StructScalar: {'mode': 2.2571069235866048e-08, 'count': 1}>

In [7]: i = np.random.randint(0, 1234567, 12345678)

In [8]: time scipy.stats.mode(i)
CPU times: user 1.03 s, sys: 3.11 ms, total: 1.03 s
Wall time: 1.03 s
Out[8]: ModeResult(mode=array([607002]), count=array([28]))

In [9]: time pc.mode(i)[0]
CPU times: user 1.57 s, sys: 0 ns, total: 1.57 s
Wall time: 1.57 s
Out[9]: <pyarrow.StructScalar: {'mode': 607002, 'count': 28}>
{noformat}



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