>>> from sklearn.preprocessing import OneHotEncoder
>>> enc = OneHotEncoder()

>>> enc.fit([[0, 0, 3], [1, 1, 0], [0, 2, 1], [1, 0, 2]])  

>>> enc.n_values_
array([2, 3, 4])

>>> enc.feature_indices_
array([0, 2, 5, 9])

>>> enc.transform([[0, 1, 1]]).toarray()
array([[ 1.,  0.,  0.,  1.,  0.,  0.,  1.,  0.,  0.]])
 

註意：僅僅是數值型字段才可以，如果是字符類型字段則不能直接搞定

需要使用pandas get_dummies搞定

例如：

Using the get_dummies will create a new column for every unique string in a certain column:使用get_dummies進行one-hot編碼

1. pd.get_dummies(df)

還可以：

import pandas as pd
import numpy as np
from sklearn_pandas import DataFrameMapper
from sklearn.preprocessing import
 
 OneHotEncoder

data = pd.DataFrame({‘text‘:[‘aaa‘, ‘bbb‘], ‘number_1‘:[1, 1], ‘number_2‘:[2, 2]})

#    number_1  number_2 text
# 0         1         2  aaa
# 1         1         2  bbb

# SomeEncoder here must be any encoder which will help you to get
# numerical representation from text column
mapper = DataFrameMapper([
    (
 
‘text‘, SomeEncoder),
    ([‘number_1‘, ‘number_2‘], OneHotEncoder())
])
mapper.fit_transform(data)

sklearn.preprocessing OneHotEncoder——僅僅是數值型字段才可以，如果是字符類型字段則不能直接搞定