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Posted to jira@arrow.apache.org by "Jacob Wujciak-Jens (Jira)" <ji...@apache.org> on 2022/04/08 12:29:00 UTC

[jira] [Updated] (ARROW-15474) [Python] Possibility of a table.drop_duplicates() function?

     [ https://issues.apache.org/jira/browse/ARROW-15474?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jacob Wujciak-Jens updated ARROW-15474:
---------------------------------------
    Component/s: Python

> [Python] Possibility of a table.drop_duplicates() function?
> -----------------------------------------------------------
>
>                 Key: ARROW-15474
>                 URL: https://issues.apache.org/jira/browse/ARROW-15474
>             Project: Apache Arrow
>          Issue Type: Wish
>          Components: Python
>    Affects Versions: 6.0.1
>            Reporter: Lance Dacey
>            Priority: Major
>             Fix For: 8.0.0
>
>
> I noticed that there is a group_by() and sort_by() function in the 7.0.0 branch. Is it possible to include a drop_duplicates() function as well? 
> ||id||updated_at||
> |1|2022-01-01 04:23:57|
> |2|2022-01-01 07:19:21|
> |2|2022-01-10 22:14:01|
> Something like this which would return a table without the second row in the example above would be great. 
> I usually am reading an append-only dataset and then I need to report on latest version of each row. To drop duplicates, I am temporarily converting the append-only table to a pandas DataFrame, and then I convert it back to a table and save a separate "latest-version" dataset.
> {code:python}
> table.sort_by(sorting=[("id", "ascending"), ("updated_at", "ascending")]).drop_duplicates(subset=["id"] keep="last")
> {code}



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