[ARROW-2443] [Python] Conversion from pandas of empty categorical fails with ArrowInvalid

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 0.9.0
• Fix Version/s: 0.10.0
• Component/s: Python
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/18577
• Assignee: Uwe Korn
• Reporter: Florian Jetter
• Created: 10/Apr/18 14:37
• Updated: 11/Jan/23 07:21
• Resolved: 19/Apr/18 14:43

Description

The conversion of an empty pandas categorical raises an exception. Before version `0.9.0` this was possible

import pandas as pd
import pyarrow as pa
pa.Table.from_pandas(pd.DataFrame({'cat': pd.Categorical([])}))

raises:

ArrowInvalid: Dictionary indices must have non-zero length

Issue Links

• links to: GitHub Pull Request #1906