https://nbviewer.jupyter.org/github/donggu26/donggu/blob/master/KNN%E7%AE%97%E6%B3%95%E7%9A%84%E7%90%86%E8%A7%A3.ipynb
KNN算法、K近邻算法
原文：https://www.cnblogs.com/xiaodonggu/p/11593300.html
