[jira] [Commented] (ARROW-13784) [Python] Table.from_arrays should raise an error when array is empty but names is not

["Abderrahmane Jaidi (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-13784?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17408853#comment-17408853 ] 

Abderrahmane Jaidi commented on ARROW-13784:
--------------------------------------------

Thanks [~jorisvandenbossche], wouldn't raising an error be a breaking change to users though? Code that was returning a table with an empty schema is now suddenly raising an error

> [Python] Table.from_arrays should raise an error when array is empty but names is not
> -------------------------------------------------------------------------------------
>
>                 Key: ARROW-13784
>                 URL: https://issues.apache.org/jira/browse/ARROW-13784
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: Python
>    Affects Versions: 4.0.1
>            Reporter: Abderrahmane Jaidi
>            Priority: Major
>              Labels: good-first-issue
>
> The `Table.from_arrays` method returns an empty schema when supplying an empty arrays list but providing column names. As a result, the subsequent `to_pandas` method returns an empty data frame with no column names.
> ```
> {{import pyarrow as pa}}
> {{arrays = []}}
> {{cols_names = ["col1", "col2"]}}
> {{table = pa.Table.from_arrays(arrays=arrays, names=cols_names)}}
> {{table.schema  # returns nothing}}
> {{df = table.to_pandas()}}
> {{df.head()}}
> {{Empty DataFrame
> Columns: []
> Index: [] # Expected column names to be visible here}}
> ```
> I assume that this is because a schema cannot be built without data types?



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