BUG: Groupby object does not implement len() method #442
Description
Describe the bug
Groupby object does not implement len() method.
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 [1]: import xorbits.pandas as pd
In [2]: df = pd.DataFrame({'a': ['a', 'b', 'a', 'c'], 'b': [0.1, 0.2, 0.3, 0.4], 'c': ['aa', 'bb', 'cc', 'aa']})
In [3]: grouped = df.groupby('b')
In [4]: len(grouped)
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
Cell In[4], line 1
----> 1 len(grouped)
File ~/Workspace/xorbits/python/xorbits/core/data.py:267, in DataRef.__len__(self)
263 raise TypeError(
264 f"object with shape {self.data._mars_entity.shape} has no len()"
265 )
266 else:
--> 267 raise TypeError(f"object of type '{self.data.data_type}' has no len()")
TypeError: object of type 'DataType.dataframe_groupby' has no len()
Expected behavior
__len__() implementd.