[jira] [Assigned] (ARROW-13926) [R] Support mutate/summarize with implicit join

["Neal Richardson (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/ARROW-13926?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Neal Richardson reassigned ARROW-13926:
---------------------------------------

    Assignee: Neal Richardson

> [R] Support mutate/summarize with implicit join
> -----------------------------------------------
>
>                 Key: ARROW-13926
>                 URL: https://issues.apache.org/jira/browse/ARROW-13926
>             Project: Apache Arrow
>          Issue Type: New Feature
>          Components: R
>            Reporter: Neal Richardson
>            Assignee: Neal Richardson
>            Priority: Major
>             Fix For: 6.0.0
>
>
> {code}
> mtcars %>%
>   group_by(cyl) %>%
>   mutate(x = hp - mean(hp)
> {code}
> essentially means something like
> {code}
> mtcars %>%
>   left_join(mtcars %>%
>     group_by(cyl) %>%
>     summarize(tmp = mean(hp))
>   ) %>%
>   mutate(x = hp - tmp) %>%
>   select(-tmp)
> {code}
> Apparently you can do the same inside summarize() too (though IDK if that's behavior we want to encourage). Once we can do joins, we can support these queries.



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