Use TF-IDF for document categorization

The principle of this method is relatively simple, you can refer to: 1, TF-IDF and cosine similarity Application (a): Automatic extraction of keywords 2, TF-IDF and cosine similarity application (ii): Find similar article 3, How to calculate the similarity of two documents (i) 4, Gensim do a theme model
5, of course, can also see Dr. Wu's "Mathematical Beauty" 11th chapter How to determine the relevance of Web pages and queries.
The 4th article ( Gensim ) uses the Python Gensim Toolkit for document similarity comparisons using TF-IDF, LDA, and LSI.