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https://issues.apache.org/jira/browse/ARROW-1732?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16219886#comment-16219886
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ASF GitHub Bot commented on ARROW-1732:
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wesm opened a new pull request #1252: ARROW-1732: [Python] Permit creating
record batches with no columns, test pandas roundtrips
URL: https://github.com/apache/arrow/pull/1252
I ran into this rough edge today, invariably serialization code paths will
need to send across a DataFrame with no columns, this will need to work even if
`preserve_index=False`
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> [Python] RecordBatch.from_pandas fails on DataFrame with no columns when
> preserve_index=False
> ---------------------------------------------------------------------------------------------
>
> Key: ARROW-1732
> URL: https://issues.apache.org/jira/browse/ARROW-1732
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Reporter: Wes McKinney
> Assignee: Wes McKinney
> Labels: pull-request-available
> Fix For: 0.8.0
>
>
> I believe this should have well-defined behavior and not raise an error:
> {code}
> In [5]: pa.RecordBatch.from_pandas(pd.DataFrame({}), preserve_index=False)
> ---------------------------------------------------------------------------
> ValueError Traceback (most recent call last)
> <ipython-input-5-4dda72b47dbd> in <module>()
> ----> 1 pa.RecordBatch.from_pandas(pd.DataFrame({}), preserve_index=False)
> ~/code/arrow/python/pyarrow/table.pxi in pyarrow.lib.RecordBatch.from_pandas
> (/home/wesm/code/arrow/python/build/temp.linux-x86_64-3.5/lib.cxx:39957)()
> 586 df, schema, preserve_index, nthreads=nthreads
> 587 )
> --> 588 return cls.from_arrays(arrays, names, metadata)
> 589
> 590 @staticmethod
> ~/code/arrow/python/pyarrow/table.pxi in pyarrow.lib.RecordBatch.from_arrays
> (/home/wesm/code/arrow/python/build/temp.linux-x86_64-3.5/lib.cxx:40130)()
> 615
> 616 if not number_of_arrays:
> --> 617 raise ValueError('Record batch cannot contain no arrays
> (for now)')
> 618
> 619 num_rows = len(arrays[0])
> ValueError: Record batch cannot contain no arrays (for now)
> {code}
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