TF is straight forward, you can simply count the no of occurrences in the doc by simple string matching. For IDF you need to know total no of docs in the collection and the no. of docs having the bigram. reader.maxDoc() will give you the total no of docs in the collection. To calculate the number of docs containing the bigram use a phrase query with slop factor set to 0. The number of docs returned by the indexsearcher with the phrase query will be the number of docs having the bigram. I hope this is fine.
Alternatively, use NGramTokenizer where ( n=2 in your case) while indexing. In such a case, each bigram can interpreted as a normal lucene term. Thanks, Parnab On Wed, Jul 2, 2014 at 8:45 AM, Manjula Wijewickrema <manjul...@gmail.com> wrote: > Hi, > > Could please explain me how to determine the tf-idf score for bigrams. My > program is able to index and search bigrams correctly, but it does not > calculate the tf-idf for bigrams. If someone can, please help me to resolve > this. > > Regards, > Manjula. >
