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https://issues.apache.org/jira/browse/ARROW-13151?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17425351#comment-17425351
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Micah Kornfield commented on ARROW-13151:
-----------------------------------------
With the PR that is up this now seems to work:
{code:java}
>>> data = {"root": [[\{"addr": {"this": 3, "that": 3}}]]}
>>> table = pa.Table.from_pydict(data)
>>> pq.write_table(table, "/tmp/table.parquet")
>>> file = pq.ParquetFile("/tmp/table.parquet")
>>> array = file.read(["root.list.item.addr.that"])
>>> array
pyarrow.Table
root: list<item: struct<addr: struct<that: int64>>>
child 0, item: struct<addr: struct<that: int64>>
child 0, addr: struct<that: int64>
child 0, that: int64
----
root: [[ – is_valid: all not null
– child 0 type: struct<that: int64>
– is_valid: all not null
– child 0 type: int64
[
3
]]]
{code}
> [Python] Unable to read single child field of struct column from Parquet
> ------------------------------------------------------------------------
>
> Key: ARROW-13151
> URL: https://issues.apache.org/jira/browse/ARROW-13151
> Project: Apache Arrow
> Issue Type: Bug
> Components: Parquet, Python
> Reporter: Angus Hollands
> Assignee: Micah Kornfield
> Priority: Major
> Labels: pull-request-available
> Fix For: 6.0.0
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Given the following table
> {code:java}
> data = {"root": [[{"addr": {"this": 3, "that": 3}}]]}
> table = pa.Table.from_pydict(data)
> {code}
> reading the nested column leads to an {{pyarrow.lib.ArrowInvalid}} error:
> {code:java}
> pq.write_table(table, "/tmp/table.parquet")
> file = pq.ParquetFile("/tmp/table.parquet")
> array = file.read(["root.list.item.addr.that"])
> {code}
> Traceback:
> {code:java}
> Traceback (most recent call last):
> File "....", line 21, in <module>
> array = file.read(["root.list.item.addr.that"])
> File
> "/home/angus/.mambaforge/envs/awkward/lib/python3.9/site-packages/pyarrow/parquet.py",
> line 383, in read
> return self.reader.read_all(column_indices=column_indices,
> File "pyarrow/_parquet.pyx", line 1097, in
> pyarrow._parquet.ParquetReader.read_all
> File "pyarrow/error.pxi", line 97, in pyarrow.lib.check_status
> pyarrow.lib.ArrowInvalid: List child array invalid: Invalid: Struct child
> array #0 does not match type field: struct<that: int64> vs struct<that:
> int64, this: int64>
> {code}
> It's possible that I don't quite understand this properly - am I doing
> something wrong?
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