[jira] [Commented] (ARROW-2128) [Python] Cannot serialize array of empty lists

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-2128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16360006#comment-16360006 ] 

ASF GitHub Bot commented on ARROW-2128:
---------------------------------------

xhochy opened a new pull request #1587: ARROW-2128: [Python] Support arrays of empty lists
URL: https://github.com/apache/arrow/pull/1587
 
 
   

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> [Python] Cannot serialize array of empty lists
> ----------------------------------------------
>
>                 Key: ARROW-2128
>                 URL: https://issues.apache.org/jira/browse/ARROW-2128
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: Python
>    Affects Versions: 0.8.0
>            Reporter: Uwe L. Korn
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 0.9.0
>
>
> This currently failing:
> {code:java}
> data = pd.Series([[], [], []])
> arr = pa.array(data)
> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
> array.pxi:181: in pyarrow.lib.array
> ???
> array.pxi:26: in pyarrow.lib._sequence_to_array
> ???
> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
> > ???
> E pyarrow.lib.ArrowTypeError: Unable to determine data type
> {code}
> The code in {{SeqVisitor::GetType}} suggests that we don't want to support thus but I would have expected that the above should result in {{List<Null>}}.



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