Armin Berres created ARROW-3652: ----------------------------------- Summary: [Python] CategoricalIndex is lost after reading back Key: ARROW-3652 URL: https://issues.apache.org/jira/browse/ARROW-3652 Project: Apache Arrow Issue Type: Bug Components: Python Reporter: Armin Berres
When a {{CategoricalIndex}} is written and read back the resulting index is not more categorical. {code} 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') ref_df = pq.read_pandas('test.parquet').to_pandas() print(df.index) # CategoricalIndex(['a', 'c'], categories=['a', 'c'], ordered=False, name='c1', dtype='category') print(ref_df.index) # Index(['a', 'c'], dtype='object', name='c1') {code} In the metadata the information is correctly contained: {code:java} {"name": "c1", "field_name": "c1", "p' b'andas_type": "categorical", "numpy_type": "int8", "metadata": {"' b'num_categories": 2, "ordered": false} {code} -- This message was sent by Atlassian JIRA (v7.6.3#76005)