digraph

代码说明：

  用于统计任一英文文档中26个字母的统计频率，得到频率矩阵(Second, it fuses the features of the first singular value component and the second one, and then gets the complex feature vectors which reflect not only the statistic frequency but also the sequential structure of letters. In the end, the cosine similarity of texts is used to measure the similarity between the query and documents.)