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https://issues.apache.org/jira/browse/ARROW-5139?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16931417#comment-16931417
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Joris Van den Bossche commented on ARROW-5139:
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Now we add the {{preserve_index=None / True}} distinction, the original example
with {{preserve_index=True}} is working again as expected.
When doing the same example with the default of None
({{pa.Table.from_pandas(df, columns=[], preserve_index=None).to_pandas()}}),
that still gives the same problem as reported.
For that one, I am not sure what is the best solution (do we want to go down
the route of a Table having 0 columns but a non-zero {{num_rows}} ?)
> [Python/C++] Empty column selection no longer restores index
> ------------------------------------------------------------
>
> Key: ARROW-5139
> URL: https://issues.apache.org/jira/browse/ARROW-5139
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++, Python
> Affects Versions: 0.12.1
> Reporter: Florian Jetter
> Priority: Minor
> Labels: parquet
> Fix For: 0.15.0
>
>
> The index of a dataframe is no longer reconstructed when using empty column
> selection. This is a regression to 0.12.1 and probably only happens for
> pd.RangeIndex
> {code:python}
> import pandas as pd
> import pyarrow as pa
> import pyarrow.parquet as pq
> from kartothek.serialization import ParquetSerializer
> from storefact import get_store_from_url
> print(pa.__version__)
> df = pd.DataFrame(
> {"a": [1, 2]}
> )
> print(df.index)
> table = pa.Table.from_pandas(df)
> buf = pa.BufferOutputStream()
> pq.write_table(table, buf)
> reader = pa.BufferReader(buf.getvalue().to_pybytes())
> table_restored = pq.read_pandas(reader, columns=[])
> df_restored = table_restored.to_pandas()
> print(len(df_restored))
> {code}
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