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https://issues.apache.org/jira/browse/ARROW-15370?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated ARROW-15370:
-----------------------------------
Labels: pull-request-available (was: )
> [Python] Regression in empty table to_pandas conversion
> -------------------------------------------------------
>
> Key: ARROW-15370
> URL: https://issues.apache.org/jira/browse/ARROW-15370
> Project: Apache Arrow
> Issue Type: Bug
> Components: Python
> Reporter: Joris Van den Bossche
> Priority: Blocker
> Labels: pull-request-available
> Fix For: 7.0.0
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Nightly integration tests with kartothek are failing, see eg
> https://github.com/ursacomputing/crossbow/runs/4863725914?check_suite_focus=true
> This seems something on our side, and a recent failure (the builds only
> started failing today, and I don't see other differences with the last
> working build yesterday)
> Update, a reproducer:
> {code}
> In [4]: df = pd.DataFrame({'a': [1, 2], 'b': [0.1, 0.2]})
> In [5]: table = pa.table(df)
> In [6]: table.schema.empty_table().to_pandas()
> ---------------------------------------------------------------------------
> ValueError Traceback (most recent call last)
> <ipython-input-6-a03ecffc0af8> in <module>
> ----> 1 table.schema.empty_table().to_pandas()
> ~/scipy/repos/arrow/python/pyarrow/array.pxi in
> pyarrow.lib._PandasConvertible.to_pandas()
> ~/scipy/repos/arrow/python/pyarrow/table.pxi in pyarrow.lib.Table._to_pandas()
> ~/scipy/repos/arrow/python/pyarrow/pandas_compat.py in
> table_to_blockmanager(options, table, categories, ignore_metadata,
> types_mapper)
> 790
> 791 axes = [columns, index]
> --> 792 return BlockManager(blocks, axes)
> 793
> 794
> ~/miniconda3/envs/arrow-dev/lib/python3.8/site-packages/pandas/core/internals/managers.py
> in __init__(self, blocks, axes, verify_integrity)
> 912 pass
> 913
> --> 914 self._verify_integrity()
> 915
> 916 def _verify_integrity(self) -> None:
> ~/miniconda3/envs/arrow-dev/lib/python3.8/site-packages/pandas/core/internals/managers.py
> in _verify_integrity(self)
> 919 for block in self.blocks:
> 920 if block.shape[1:] != mgr_shape[1:]:
> --> 921 raise construction_error(tot_items, block.shape[1:],
> self.axes)
> 922 if len(self.items) != tot_items:
> 923 raise AssertionError(
> ValueError: Empty data passed with indices specified.
> {code}
> It happens specifically if the schema still has pandas metadata that indicate
> a range for the index (which we try to recreate, but that doesn't match the
> actual length of the table).
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