title: Document Similarity in ElasticSearch
body: <p>I want to calculate similarity between two documents indexed in elasticsearch. I know it can be done in lucene using term vectors. What is the direct way to do it?</p>
  
  <p>I found that there is a similarity module doing exactly this:
  <a href="http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/index-modules-similarity.html">http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/index-modules-similarity.html</a> </p>
  
  <p>How do I integrate this in my system? I am using pyelasticsearch for calling elasticsearch commands, but I am open to use the REST api for similarity if needed.</p>