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)