BUG: df.map_chunk with empty DataFrame cannot work #723
Description
Describe the bug
df.map_chunk with empty DataFrame cannot work.
To Reproduce
To help us to reproduce this bug, please provide information below:
- Your Python version
- The version of Xorbits you use
- Versions of crucial packages, such as numpy, scipy and pandas
- Full stack of the error.
- Minimized code to reproduce the error.
In [2]: import xorbits
In [3]: xorbits.init()
2023-09-26 15:55:08,918 xorbits._mars.deploy.oscar.local 86719 WARNING Web service started at http://0.0.0.0:36934
In [4]: df = pd.DataFrame(columns=['a', 'b', 'c'])
In [5]: def p(d):
...: if not len(d):
...: return pd.DataFrame([[None] * d.shape[1]], columns=d.columns)
...: else:
...: return d
...:
In [6]: df.map_chunk(p) # should not be empty
100%|████████████████████████████████████| 100.00/100 [00:00<00:00, 2450.02it/s]
Empty DataFrame
Columns: [a, b, c]
Index: []