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https://issues.apache.org/jira/browse/ARROW-7855?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17036862#comment-17036862
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Joris Van den Bossche commented on ARROW-7855:
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What would you exactly expect in this case? Such a dict will be interpreted as
a StructType, and the values of a struct can be lists (as you have here), but
Arrow only supports homogeneously typed lists (unless you use a UnionType, but
that is not something that can be inferred I think)
> TypeError on mixed array values
> -------------------------------
>
> Key: ARROW-7855
> URL: https://issues.apache.org/jira/browse/ARROW-7855
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Affects Versions: 0.16.0, 0.15.1
> Reporter: Rob DiCiuccio
> Priority: Major
>
> The following data structure passed to `pa.array` raises a generic
> `TypeError`:
> {code:java}
> import pyarrow as pa
> pa.array([{'TestKey': [123456, 'foo']}])
> {code}
> {code:java}
> Traceback (most recent call last):
> File "pyarrow_list_test.py", line 30, in <module>
> pa_array = pa.array([\{'TestKey': [123456, 'foo']}])
> File "pyarrow/array.pxi", line 269, in pyarrow.lib.array
> File "pyarrow/array.pxi", line 38, in pyarrow.lib._sequence_to_array
> TypeError: an integer is required (got type str)
> {code}
> I understand there may be a way to overcome this by setting the `type` value
> as an argument to `pa.array`, but the use case here is storing results of a
> SQL query where the structure/type of the column is unknown.
> If Arrow is ultimately unable to handle this data structure without a
> predefined `type` passed to `pa.array`, can the exception at least us the
> PyArrow namespace (e.g. `pa.lib.ArrowTypeError` or
> `pa.lib.ArrowNotImplementedError).
> Any other workaround suggestions welcome.
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