[
https://issues.apache.org/jira/browse/ARROW-3866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17660889#comment-17660889
]
Rok Mihevc commented on ARROW-3866:
-----------------------------------
This issue has been migrated to [issue
#20443|https://github.com/apache/arrow/issues/20443] on GitHub. Please see the
[migration documentation|https://github.com/apache/arrow/issues/14542] for
further details.
> [Python] Column metadata is not transferred to tables in pyarrow
> ----------------------------------------------------------------
>
> Key: ARROW-3866
> URL: https://issues.apache.org/jira/browse/ARROW-3866
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Reporter: Seb Fru
> Assignee: Tanya Schlusser
> Priority: Major
> Labels: features, newbie, pull-request-available
> Fix For: 0.12.0
>
> Time Spent: 1.5h
> Remaining Estimate: 0h
>
> Hello everyone,
> transferring this from Github for Pyarrow. While working with pyarrow I
> noticed that field metadata does not get carried foreward when creating a
> table out of several columns. Is this intended behaviour or is there a way to
> add column metadata later on? The last command in my example does not return
> anything.
> I also could not verify whether this data would be written to parquet later
> on, because I could not find a way to add field metadata directly to a table.
>
> {code:java}
> >>> import pyarrow as pa
> >>> import pyarrow.parquet as pq
> >>> arr1 = pa.array([1,2])
> >>> arr2 = pa.array([3,4])
> >>> field1 = pa.field('field1', pa.int64())
> >>> field2 = pa.field('field2', pa.int64())
> >>> field1 = field1.add_metadata({'foo1': 'bar1'})
> >>> field2 = field2.add_metadata({'foo2': 'bar2'})
> >>> field1.metadata
> {b'foo1': b'bar1'}
> >>> field2.metadata
> {b'foo2': b'bar2'}
> >>> col1 = pa.column(field1, arr1)
> >>> col2 = pa.column(field2, arr2)
> >>> col1.field.metadata
> {b'foo1': b'bar1'}
> >>> tab = pa.Table.from_arrays([col1, col2])
> >>> tab
> pyarrow.Table field1: int64 field2: int64
> >>> tab.column(0).field.metadata
> {code}
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
