title: finding number of documents per topic for LDA with scikit-learn
body: <p>I'm following along with the scikit-learn LDA example <a href="http://scikit-learn.org/stable/auto_examples/applications/topics_extraction_with_nmf_lda.html" rel="noreferrer">here</a> and am trying to understand how I can (if possible) surface how many documents have been labeled as having each one of these topics. I've been poring through the docs for the LDA model <a href="http://scikit-learn.org/stable/modules/generated/sklearn.decomposition.LatentDirichletAllocation.html" rel="noreferrer">here</a> but don't see where I could get this number. Has anyone been able to do this before with scikit-learn?</p>