中文说明：knn-K近邻法实现两分类的函数代码，输入为两类的样本特征，和待测试的样本向量，输出为分类结果。
English Description：
Knn-k nearest neighbor method realizes the function code of two categories, the input is the sample features of two categories, and the sample vector to be tested, and the output is the classification result.