[
https://issues.apache.org/jira/browse/ARROW-7071?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16968354#comment-16968354
]
Joris Van den Bossche commented on ARROW-7071:
----------------------------------------------
Now, I think the main question is: what API could we offer for this?
* A method on Array? Something like {{array.set_validity_bitmap(..)}} or
{{array.set_null_bitmap(..)}} (but not sure if it needs to be that clearly
exposed)
* A settable attribute like {{array.null_bitmap}}
* A function to create a new array from a given array + bitmap? This could be
similar to {{Array.from_buffers}}, but then a bit more convenient to use (as
currently you can already use that to achieve this purpose)
* Alternative could be to expand {{pa.array(values, mask=[..])}} to accept a
pyarrow array as values, and then use the {{mask}} keyword to specify the nulls
as a boolean mask (although the current behaviour here is to have the final
bitmap be a combination of nulls in the values and the mask, so this is not a
way to override the bitmap, but maybe that's actually good)
A way to avoid the issue of "previously-null values" could also be to only
allow setting the bitmap if there was not yet one before.
That would be enough for my original use case for this, where I want to create
a StructArray from two pyarrow arrays, but also give it a null bitmap:
{code}
pa.StructArray.from_arrays([pa.array([1, 2, 3]), pa.array([2, 3, 4])],
names=['a', 'b'])
{code}
For this very specific case, an option could also be to be able to pass a
bitmap or mask keyword to {{pa.StructArray.from_arrays}}, but that's of course
not a general solution for other types.
> [Python] Add Array convenience method to create "masked" view with different
> validity bitmap
> --------------------------------------------------------------------------------------------
>
> Key: ARROW-7071
> URL: https://issues.apache.org/jira/browse/ARROW-7071
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Python
> Reporter: Wes McKinney
> Priority: Major
> Fix For: 1.0.0
>
>
> NB: I'm not sure what kind of pitfalls there might be if replacing an
> existing validity bitmap and exposing some previously-null values
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
