pandas中one-hot编码的神坑

import pandas as pd
import numpy as np
a = [1, 2, 3, 1]
one_hot = pd.get_dummies(a)
print(one_hot.dtypes)
print(one_hot)
print(-one_hot)

1    uint8
2    uint8
3    uint8
dtype: object
1  2  3
0  1  0  0
1  0  1  0
2  0  0  1
3  1  0  0
1    2    3
0  255    0    0
1    0  255    0
2    0    0  255
3  255    0    0

正确的做法是，将其转换成浮点：

one_hot = one_hot.astype('float')
print(-one_hot)

1    2    3
0 -1.0 -0.0 -0.0
1 -0.0 -1.0 -0.0
2 -0.0 -0.0 -1.0
3 -1.0 -0.0 -0.0