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Posted to issues@arrow.apache.org by "Joris Van den Bossche (JIRA)" <ji...@apache.org> on 2019/05/09 10:20:00 UTC
[jira] [Comment Edited] (ARROW-2667) [C++/Python] Add pandas-like take method to Array/Column/ChunkedArray
[ https://issues.apache.org/jira/browse/ARROW-2667?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16836268#comment-16836268 ]
Joris Van den Bossche edited comment on ARROW-2667 at 5/9/19 10:19 AM:
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{quote}Note that pandas' `take` is a bit complicated by trying to satisfy two APIs simultaneously.
[...]
And then there's the "pandas" style `take` where `-1` means "indicator for missing values, which should be filled with the `na_value` parameter." Other negative numbers are not allowed.{quote}
I think this distinction in Arrow is less relevant / easier to deal with. The indices can also have nulls, resulting of nulls in the returned array. This basically takes the role of the -1 in the "pandas style" take.
(working on the Array part in ARROW-5291 / https://github.com/apache/arrow/pull/4281)
was (Author: jorisvandenbossche):
{quote}Note that pandas' `take` is a bit complicated by trying to satisfy two APIs simultaneously.
[...]
And then there's the "pandas" style `take` where `-1` means "indicator for missing values, which should be filled with the `na_value` parameter." Other negative numbers are not allowed.{quote}
I think this distinction in Arrow is less relevant / easier to deal with. The indices can also have nulls, resulting of nulls in the returned array. This basically takes the role of the -1 in the "pandas style" take.
(working on the Array part in https://github.com/apache/arrow/pull/4281)
> [C++/Python] Add pandas-like take method to Array/Column/ChunkedArray
> ---------------------------------------------------------------------
>
> Key: ARROW-2667
> URL: https://issues.apache.org/jira/browse/ARROW-2667
> Project: Apache Arrow
> Issue Type: Improvement
> Components: C++, Python
> Reporter: Uwe L. Korn
> Priority: Major
> Fix For: 0.14.0
>
>
> We should add a {{take}} method to {{Array/ChunkedArray/Column}} that takes a list of indices and returns a reordered array.
> For reference, see Pandas' interface: https://github.com/pandas-dev/pandas/blob/2cbdd9a2cd19501c98582490e35c5402ae6de941/pandas/core/arrays/base.py#L466
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