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Posted to issues@arrow.apache.org by "Antoine Pitrou (Jira)" <ji...@apache.org> on 2019/11/14 17:20:00 UTC
[jira] [Resolved] (ARROW-6749) [Python] Conversion of non-ns
timestamp array to numpy gives wrong values
[ https://issues.apache.org/jira/browse/ARROW-6749?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Antoine Pitrou resolved ARROW-6749.
-----------------------------------
Fix Version/s: 1.0.0
Resolution: Fixed
Issue resolved by pull request 5718
[https://github.com/apache/arrow/pull/5718]
> [Python] Conversion of non-ns timestamp array to numpy gives wrong values
> -------------------------------------------------------------------------
>
> Key: ARROW-6749
> URL: https://issues.apache.org/jira/browse/ARROW-6749
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Reporter: Joris Van den Bossche
> Assignee: Joris Van den Bossche
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.0.0
>
> Time Spent: 3h
> Remaining Estimate: 0h
>
> {code}
> In [25]: np_arr = np.arange("2012-01-01", "2012-01-06", int(1e6)*60*60*24, dtype="datetime64[us]")
> In [26]: np_arr
> Out[26]:
> array(['2012-01-01T00:00:00.000000', '2012-01-02T00:00:00.000000',
> '2012-01-03T00:00:00.000000', '2012-01-04T00:00:00.000000',
> '2012-01-05T00:00:00.000000'], dtype='datetime64[us]')
> In [27]: arr = pa.array(np_arr)
> In [28]: arr
> Out[28]:
> <pyarrow.lib.TimestampArray object at 0x7f0b2ef07ee8>
> [
> 2012-01-01 00:00:00.000000,
> 2012-01-02 00:00:00.000000,
> 2012-01-03 00:00:00.000000,
> 2012-01-04 00:00:00.000000,
> 2012-01-05 00:00:00.000000
> ]
> In [29]: arr.type
> Out[29]: TimestampType(timestamp[us])
> In [30]: arr.to_numpy()
> Out[30]:
> array(['1970-01-16T08:09:36.000000000', '1970-01-16T08:11:02.400000000',
> '1970-01-16T08:12:28.800000000', '1970-01-16T08:13:55.200000000',
> '1970-01-16T08:15:21.600000000'], dtype='datetime64[ns]')
> {code}
> So it seems to simply interpret the integer microsecond values as nanoseconds when converting to numpy.
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