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Posted to issues@arrow.apache.org by "Krisztian Szucs (JIRA)" <ji...@apache.org> on 2018/09/10 12:21:01 UTC
[jira] [Updated] (ARROW-2646) [C++/Python] Pandas roundtrip for
date objects
[ https://issues.apache.org/jira/browse/ARROW-2646?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Krisztian Szucs updated ARROW-2646:
-----------------------------------
Component/s: C++
> [C++/Python] Pandas roundtrip for date objects
> ----------------------------------------------
>
> Key: ARROW-2646
> URL: https://issues.apache.org/jira/browse/ARROW-2646
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++, Python
> Affects Versions: 0.9.0
> Reporter: Florian Jetter
> Assignee: Krisztian Szucs
> Priority: Minor
> Labels: pull-request-available
> Fix For: 0.11.0
>
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> Arrow currently casts date objects to nanosecond precision datetime objects. I'd like to have a way to preserve the type during a roundtrip
> {code}
> >>> import pandas as pd
> >>> import pyarrow as pa
> >>> import datetime
> >>> pa.date32().to_pandas_dtype()
> dtype('<M8[ns]')
> >>> df = pd.DataFrame({'date': [datetime.date(2018, 1, 1)]})
> >>> df.dtypes
> date object
> dtype: object
> >>> df_rountrip = pa.Table.from_pandas(df).to_pandas()
> >>> df_rountrip.dtypes
> date datetime64[ns]
> dtype: object
> {code}
> I'd expect something like this to work:
> {code}
> >>> import pandas.testing as pdt
> >>> df_rountrip = pa.Table.from_pandas(df).to_pandas(date_as_object=True)
> >>> pdt.assert_frame_equal(df_rountrip, df)
> {code}
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