这个包里包含了两个函数，是NMI指标的两种实现方式，nmi_saveTime函数运用了矩阵运算，有效节省了计算时间，可用于数据量大的时候对聚类或者分类算法结果进行评价(This package contains two functions that both achieve the calculation of the NMI index, one of which has applied matrix operation to improve the efficiency so that can be used in the evaluation of clutering algorithm when data is enormous.)