TargetEncoder#fit() could not accept Pandas DataFrame

[momijiame]

Abstract

I have confirmed that TargetEncoder#fit() method could not accept Pandas DataFrame.

How to reproduce

The following is reproducible snipet.

>>> import pandas as pd
>>> data = {
...     "group": ["A", "A", "A"],
...     "target": [1, 2, 3],
... }
>>> df = pd.DataFrame(data)
>>> 
>>> import xfeat
>>> encoder = xfeat.TargetEncoder(input_cols=["group"], target_col="target")
>>> 
>>> encoder.fit(df)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/amedama/.virtualenvs/py39/lib/python3.9/site-packages/xfeat/cat_encoder/_target_encoder.py", line 136, in fit
    target_encoder.fit(input_df[col], input_df[self._target_col])
  File "/Users/amedama/.virtualenvs/py39/lib/python3.9/site-packages/xfeat/cat_encoder/_target_encoder.py", line 220, in fit
    raise RuntimeError
RuntimeError

Probably this behavior is not expected.
Because TargetEncoder#fit_transform() method accepts Pandas DataFrame.

>>> encoder.fit_transform(df)
  group  target  group_te
0     A       1       2.5
1     A       2       2.0
2     A       3       1.5

What is happen

There is Incomplete conditional branch in TargetEncoder#fit() method.

https://github.com/pfnet-research/xfeat/blob/v0.1.1/xfeat/cat_encoder/_target_encoder.py#L214,L220

The above only includes considerations for CuDF and NumPy.
Therefore, RuntimeError will be raised by Pandas Series.

Workaround

I could not find it.

Environment

$ python -V
Python 3.9.13
$ pip list | grep xfeat                   
xfeat                         0.1.1