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Posted to issues@spark.apache.org by "Maciej Szymkiewicz (JIRA)" <ji...@apache.org> on 2017/05/03 12:19:04 UTC

[jira] [Commented] (SPARK-12467) Get rid of sorting in Row's constructor in pyspark

    [ https://issues.apache.org/jira/browse/SPARK-12467?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15994748#comment-15994748 ] 

Maciej Szymkiewicz commented on SPARK-12467:
--------------------------------------------

Python before 3.6 does not preserve the order of the keyword arguments (PEP 468) so without sorting keyword becomes nondeterministic,

> Get rid of sorting in Row's constructor in pyspark
> --------------------------------------------------
>
>                 Key: SPARK-12467
>                 URL: https://issues.apache.org/jira/browse/SPARK-12467
>             Project: Spark
>          Issue Type: Bug
>          Components: PySpark, SQL
>    Affects Versions: 1.5.2
>            Reporter: Irakli Machabeli
>            Priority: Minor
>
> Current implementation of Row's __new__ sorts columns by name
> First of all there is no obvious reason to sort, second, if one converts dataframe to rdd and than back to dataframe, order of column changes. While this is not  a bug, nevetheless it makes looking at the data really inconvenient.
>     def __new__(self, *args, **kwargs):
>         if args and kwargs:
>             raise ValueError("Can not use both args "
>                              "and kwargs to create Row")
>         if args:
>             # create row class or objects
>             return tuple.__new__(self, args)
>         elif kwargs:
>             # create row objects
>             names = sorted(kwargs.keys()) # just get rid of sorting here!!!
>             row = tuple.__new__(self, [kwargs[n] for n in names])
>             row.__fields__ = names
>             return row
>         else:
>             raise ValueError("No args or kwargs")



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