[BUG] LabelEncoder can't encode cupy array

[daxiongshu]

Describe the bug
cuml.preprocessing.LabelEncoder can't encode cupy.ndarray. it can only encode cudf.Series. In comparison, sklearn LabelEncoder can encode both pandas.Series and numpy.ndarray.

Steps/Code to reproduce bug

import cuml
import cupy
x = cupy.array([1,2,3])
lbl = cuml.preprocessing.LabelEncoder()
lbl.fit(x)

output:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-5-1ce7fdb217b0> in <module>
----> 1 lbl.fit(x)

/raid/data/ml/anaconda3/envs/cuml_dev/lib/python3.9/site-packages/cuml/internals/api_decorators.py in inner(*args, **kwargs)
    358         def inner(*args, **kwargs):
    359             with self._recreate_cm(func, args):
--> 360                 return func(*args, **kwargs)
    361 
    362         return inner

/raid/data/ml/anaconda3/envs/cuml_dev/lib/python3.9/site-packages/cuml/preprocessing/LabelEncoder.py in fit(self, y, _classes)
    179             self.classes_ = _classes
    180         else:
--> 181             self.classes_ = y.unique()  # dedupe and sort
    182 
    183         self._fitted = True

AttributeError: 'cupy._core.core.ndarray' object has no attribute 'unique'

Expected behavior
output:

array([0, 1, 2])

Environment details (please complete the following information):

• Environment location: Bare-metal
• Linux Distro/Architecture: Ubuntu 18.04 amd64
• GPU Model/Driver: V100 and driver 495.44
• CUDA: 11.5
• Method of cuDF & cuML install: from source

[github-actions]

This issue has been labeled inactive-30d due to no recent activity in the past 30 days. Please close this issue if no further response or action is needed. Otherwise, please respond with a comment indicating any updates or changes to the original issue and/or confirm this issue still needs to be addressed. This issue will be labeled inactive-90d if there is no activity in the next 60 days.

[daxiongshu]

issue closed with above PR