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Posted to issues@arrow.apache.org by "Wes McKinney (Jira)" <ji...@apache.org> on 2020/05/07 16:25:00 UTC
[jira] [Resolved] (ARROW-8641) [Python] Regression in feather: no
longer supports permutation in column selection
[ https://issues.apache.org/jira/browse/ARROW-8641?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Wes McKinney resolved ARROW-8641.
---------------------------------
Resolution: Fixed
Issue resolved by pull request 7122
[https://github.com/apache/arrow/pull/7122]
> [Python] Regression in feather: no longer supports permutation in column selection
> ----------------------------------------------------------------------------------
>
> Key: ARROW-8641
> URL: https://issues.apache.org/jira/browse/ARROW-8641
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++, Python
> Reporter: Joris Van den Bossche
> Priority: Major
> Labels: pull-request-available
> Fix For: 0.17.1, 1.0.0
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> A quite annoying regression (original report from https://github.com/pandas-dev/pandas/issues/33878), is that when specifying {{columns}} to read, this now fails if the order of the columns is not exactly the same as in the file:
> {code:python}
> In [27]: table = pa.table([[1, 2, 3], [4, 5, 6], [7, 8, 9]], names=['a', 'b', 'c'])
> In [29]: from pyarrow import feather
> In [30]: feather.write_feather(table, "test.feather")
> # this works fine
> In [32]: feather.read_table("test.feather", columns=['a', 'b'])
> Out[32]:
> pyarrow.Table
> a: int64
> b: int64
> In [33]: feather.read_table("test.feather", columns=['b', 'a'])
> ---------------------------------------------------------------------------
> ArrowInvalid Traceback (most recent call last)
> <ipython-input-33-e01caeabb389> in <module>
> ----> 1 feather.read_table("test.feather", columns=['b', 'a'])
> ~/scipy/repos/arrow/python/pyarrow/feather.py in read_table(source, columns, memory_map)
> 237 return reader.read_indices(columns)
> 238 elif all(map(lambda t: t == str, column_types)):
> --> 239 return reader.read_names(columns)
> 240
> 241 column_type_names = [t.__name__ for t in column_types]
> ~/scipy/repos/arrow/python/pyarrow/feather.pxi in pyarrow.lib.FeatherReader.read_names()
> ~/scipy/repos/arrow/python/pyarrow/error.pxi in pyarrow.lib.check_status()
> ArrowInvalid: Schema at index 0 was different:
> b: int64
> a: int64
> vs
> a: int64
> b: int64
> {code}
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