Armin Berres created ARROW-3654:
-----------------------------------
Summary: [Python] Column with CategoricalIndex fails to be read
back
Key: ARROW-3654
URL: https://issues.apache.org/jira/browse/ARROW-3654
Project: Apache Arrow
Issue Type: Bug
Components: Python
Affects Versions: 0.11.1
Reporter: Armin Berres
When a column with a \{Categoricalndex} is written the data can never be read
back.
{code:python}
df = pd.DataFrame([['a', 'b'], ['c', 'd']], columns=['c1', 'c2'])
df['c1'] = df['c1'].astype('category')
df = df.set_index(['c1'])
table = pa.Table.from_pandas(df)
pq.write_table(table, 'test.parquet')
pq.read_pandas('test.parquet').to_pandas()
{code}
Results in
{code}
KeyError Traceback (most recent call last)
~/venv/mpptool/lib/python3.7/site-packages/pyarrow/pandas_compat.py in
_pandas_type_to_numpy_type(pandas_type)
676 try:
--> 677 return _pandas_logical_type_map[pandas_type]
678 except KeyError:
KeyError: 'categorical'
{code}
The schema looks good:
{code}
column_indexes": [{"name": "c1", "field_name": "c1", "pandas_type":
"categorical", "numpy_type": "int8", "metadata": {"num_categories": 2,
"ordered": false}}]
{code}
--
This message was sent by Atlassian JIRA
(v7.6.3#76005)
