文件为tf-idf的代码实现，常用来计算特征项在文本中的权重值-File for TF-IDF' s code, used to calculate the weight value of the feature item in the text

这里会用到TF/IDF权重，用余弦夹角计算文本相似度，用方差计算两个数据间欧式距离，用k-means进行数据聚类等数学和统计知识。-Here will use the TF/IDF weight, with cosine angle calculation of text similarity, with the variance of the two data between the data of the European distance, with K-means data cluste

用于计算TF-IDF权重值，便于后续进行特征提取等工作(for calculating the weighted value of TF-IDF)