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https://issues.apache.org/jira/browse/ARROW-12911?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Nic Crane updated ARROW-12911:
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Summary: [Python] sum of zero rows gives null; should give 0 (was: sum of
zero rows gives null; should give 0)
> [Python] sum of zero rows gives null; should give 0
> ---------------------------------------------------
>
> Key: ARROW-12911
> URL: https://issues.apache.org/jira/browse/ARROW-12911
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++, Python
> Affects Versions: 4.0.1
> Reporter: Adam Hooper
> Assignee: Yibo Cai
> Priority: Minor
>
> {code}
> >>> pa.compute.sum(pa.array([], pa.int64()))
> <pyarrow.Int64Scalar: None>
> {code}
> I'd expect 0.
> I can't think of any reason for NULL, except that SQL returns NULL. But I
> can't figure out why SQL returns NULL. Does anybody know? Any textbook -- and
> https://en.wikipedia.org/wiki/Summation -- specifies 0.
> Pandas and Numpy return 0. Also, Apache Arrow c_glib implementation returns 0
> -- and even tests for it:
> https://github.com/apache/arrow/blob/master/c_glib/test/test-int8-array.rb#L60
> Workaround is to replace all NULLs with 0 after running the computation.
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