[PARQUET-1015] Object categoricals are not serialized when only None is present

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: cpp-1.1.0
• Fix Version/s: cpp-1.3.0
• Component/s: parquet-cpp
• Assignee: Uwe Korn
• Reporter: Marco Neumann
• Created: 02/Jun/17 08:16
• Updated: 02/Jan/18 15:16
• Resolved: 02/Jan/18 15:16

Description

The following code sample fails with pyarrow.lib.ArrowNotImplementedError: NotImplemented: unhandled type but should not:

import pandas as pd
import pyarrow as pa
import pyarrow.parquet as pq

df = pd.DataFrame({'x': [None]})
df['x'] = df['x'].astype('category')

table = pa.Table.from_pandas(df)
buf = pa.InMemoryOutputStream()

pq.write_table(table, buf)

Issue Links

• is blocked by: ARROW-1286 PYTHON: support Categorical serialization to/from parquet