[ARROW-18257] [Python] array of time64 type changes from Time64Type to DataType

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 10.0.0
• Fix Version/s: 11.0.0
• Component/s: Python
• Labels: pull-request-available
• Environment: python 3.9 ; pyarrow 10.0.0 ; No pandas installed
• External issue URL: https://github.com/apache/arrow/issues/33438
• Assignee: &res
• Reporter: &res
• Created: 06/Nov/22 12:04
• Updated: 11/Jan/23 11:59
• Resolved: 15/Nov/22 07:51

Description

When creating an array of time64 elements, the array type information is changed from Time64Type to DataType. 

While it's not an issue as such, given it still looks like an array of time64, I can't access special attributes of the Time64Type (for example unit)

 

dtype = pa.time64("ns")
time_array = pa.array(
    [
        1,
        2,
        3
    ],
    dtype
)
assert pa.types.is_time64(time_array.type) is True
assert isinstance(dtype, pa.Time64Type) is True
assert isinstance(time_array.type, pa.Time64Type) is False # Wrong
assert isinstance(time_array.type, pa.DataType) is True # Wrong
assert dtype == time_array.type
assert dtype.unit == "ns"
with pytest.raises(AttributeError, match=r"'pyarrow.lib.DataType' object has no attribute 'unit'"):
    # Should be able to access unit:
    time_array.type.unit

Issue Links

• links to: GitHub Pull Request #14633