[ARROW-1999] [Python] from_numpy_dtype returns wrong types

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.8.0
• Fix Version/s: 0.9.0
• Component/s: Python
• Labels: pull-request-available
• Environment: Windows 10 Build 15063.850 ; Python: 3.6.3 ; Numpy: 1.14.0
• External issue URL: https://github.com/apache/arrow/issues/15646
• Assignee: Jim Crist
• Reporter: Victor Jimenez
• Created: 15/Jan/18 22:58
• Updated: 11/Jan/23 07:18
• Resolved: 28/Jan/18 15:47

Description

The following code shows multiple issues when using from_numpy_dtype:

import numpy as np
import pyarrow as pa

pa.from_numpy_dtype(np.unicode) # returns DataType(bool)
pa.from_numpy_dtype(np.int)     # returns DataType(bool)

pa.from_numpy_dtype(np.int64) # Fails with the following message:
#
# ArrowNotImplementedError Traceback (most recent call last)
# <ipython-input-14-ca0855a7dda8> in <module>()
# ----> 1 pa.from_numpy_dtype(np.int64)
# 2
#
# types.pxi in pyarrow.lib.from_numpy_dtype()
#
# error.pxi in pyarrow.lib.check_status()
#
# ArrowNotImplementedError: Unsupported numpy type 32760

Additionally, a potentially related issue is also seen when using to_pandas_dtype:

pa.DataType.to_pandas_dtype(pa.string()) # Returns numpy.object_ 
                                         # (shouldn't it be numpy.unicode?)

Issue Links

• links to: GitHub Pull Request #1523