机器学习-one-hot 编码

https://blog.csdn.net/tengyuan93/article/details/78930285
https://www.cnblogs.com/xyou/p/9197523.html
https://blog.csdn.net/wxyangid/article/details/80209156
https://blog.csdn.net/mvpboss1004/article/details/79188190