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https://issues.apache.org/jira/browse/ARROW-15565?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Joris Van den Bossche updated ARROW-15565:
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Summary: [Python] Extension dtype in the index is not preserved on a
roundtrip from Pandas (was: [Python] Interval dtype is not preserved on a
roundtrip from Pandas and IntervalIndex)
> [Python] Extension dtype in the index is not preserved on a roundtrip from
> Pandas
> ---------------------------------------------------------------------------------
>
> Key: ARROW-15565
> URL: https://issues.apache.org/jira/browse/ARROW-15565
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Python
> Reporter: Alenka Frim
> Priority: Major
>
> Doing a roundtrip from Pandas with IntervalIndex results in an object-dtype
> index, and not a proper Intervalndex - that means the interval dtype is not
> preserved on a roundtrip, while this would be the case if it was a normal
> column instead of the index.
> Example:
> {code}
> >>> import pandas as pd
> >>> import pyarrow as pa
> >>> df = pd.DataFrame(index=pd.interval_range(start=0, end=3))
> >>> table = pa.table(df)
> >>> table.to_pandas().index
> Index([{'left': 0, 'right': 1}, {'left': 1, 'right': 2},
> {'left': 2, 'right': 3}],
> dtype='object')
> >>> df.index
> IntervalIndex([(0, 1], (1, 2], (2, 3]], dtype='interval[int64, right]')
> >>>
> {code}
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