[jira] [Commented] (ARROW-1560) [C++] Kernel implementations for "match" function

["Preeti Suman (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-1560?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16809983#comment-16809983 ] 

Preeti Suman commented on ARROW-1560:
-------------------------------------

For match (and isin) compute kernel , in left and right array, if there are nulls in the input,

a) Do we need to match null with null or ignore null completely?

    Example:

    match(['a', 'b', null], ['a', 'c', null])

    Expected output [0, null, 2]

b) If we need to compare, what will be the suggested way to traverse nulls if we use the VisitValue and VisitNull (using [ArrayDataVisitor|https://github.com/apache/arrow/blob/master/cpp/src/arrow/visitor_inline.h]{color:#000000}) for the array?{color}

> [C++] Kernel implementations for "match" function
> -------------------------------------------------
>
>                 Key: ARROW-1560
>                 URL: https://issues.apache.org/jira/browse/ARROW-1560
>             Project: Apache Arrow
>          Issue Type: New Feature
>          Components: C++
>            Reporter: Wes McKinney
>            Assignee: Preeti Suman
>            Priority: Major
>              Labels: Analytics
>             Fix For: 0.14.0
>
>
> Match computes a position index array from an array values into a set of categories
> {code}
> match(['a', 'b', 'a', null, 'b', 'a', 'b'], ['b', 'a'])
> return [1, 0, 1, null, 0, 1, 0]
> {code}



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