[jira] [Created] (ARROW-1992) to_pandas crashes when using strings_to_categoricals on empty string cols on 0.8.0

["Victor Uriarte (JIRA)" <ji...@apache.org>]

Victor Uriarte created ARROW-1992:
-------------------------------------

             Summary: to_pandas crashes when using strings_to_categoricals on empty string cols on 0.8.0
                 Key: ARROW-1992
                 URL: https://issues.apache.org/jira/browse/ARROW-1992
             Project: Apache Arrow
          Issue Type: Bug
    Affects Versions: 0.8.0
         Environment: OS: Windows
Python: PY36 x64
Pandas: 0.22.0
pyarrow: 0.8.0
            Reporter: Victor Uriarte
             Fix For: 0.7.1


When trying to read back a table, Python crashes when pyarrow is used to read/convert a table that has a column of 0 length `strings and strings_to_categorical=True`. Example code below.
This same test ran ok with pyarrow 0.7.1

```python
import pathlib

import pandas as pd

import pyarrow as pa
import pyarrow.parquet as pq

df = pd.DataFrame({
    'Foo': ['A', 'A', 'B', 'B', 'C'],
    'Bar': ['A1', 'A2', 'B2', 'D3', ''],
    'Baz': ['', '', '', '', ''],
})

test_dir = pathlib.Path(__file__).parent / 'test_bug'
test_dir.mkdir(parents=True, exist_ok=True)

table = pa.Table.from_pandas(df)

path = test_dir / 'file1.parquet'
path = str(path)  # write_table doesn't support `pathlib.Path` objects
pq.write_table(table, path)

path = test_dir / 'file2.parquet'
path = str(path)  # write_table doesn't support `pathlib.Path` objects
pq.write_table(table, path)

path = str(test_dir)  # write_table doesn't support `pathlib.Path` objects
data_set = pq.ParquetDataset(path)
table = data_set.read()

df2 = table.to_pandas(strings_to_categorical=True)
print(len(df2))
```



--
This message was sent by Atlassian JIRA
(v6.4.14#64029)