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Posted to issues@arrow.apache.org by "Antoine Pitrou (JIRA)" <ji...@apache.org> on 2019/04/23 15:21:00 UTC
[jira] [Resolved] (ARROW-5195) [Python] read_csv ignores
null_values on string types
[ https://issues.apache.org/jira/browse/ARROW-5195?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Antoine Pitrou resolved ARROW-5195.
-----------------------------------
Resolution: Fixed
Issue resolved by pull request 4188
[https://github.com/apache/arrow/pull/4188]
> [Python] read_csv ignores null_values on string types
> -----------------------------------------------------
>
> Key: ARROW-5195
> URL: https://issues.apache.org/jira/browse/ARROW-5195
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++, Python
> Affects Versions: 0.13.0
> Environment: Python 3.6, PyArrow 0.13.0, AWS linux, debian-slim in docker
> Reporter: Scott Burns
> Assignee: Antoine Pitrou
> Priority: Minor
> Labels: pull-request-available
> Fix For: 0.14.0
>
> Time Spent: 40m
> Remaining Estimate: 0h
>
> Let's write a simple CSV with NULL values in a string column:
> {quote}with open('foo.csv', 'w') as fobj:
> fobj.write('col1,col2\n1,value\n2,NULL')
> table = csv.read_csv('foo.csv')
> table.column('col2').null_count # => 0
> {quote}
>
> table.column('col2').null_count will be 0, I think it should be 1. Passing in {{ConvertOptions(null_values=["NULL"])}} doesn't help.
>
> Note that {{pandas.read_csv}} parses these NULLs correctly so I have a workaround available.
> But I'd prefer to natively read CSV from pyarrow if possible :)
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