title: Is there a way to set min_df and max_df in gensim's tfidf model?
body: <p>I am using gensim's tdidf model like so:</p>
  
  <pre><code>from gensim import corpora, models
  
  dictionary = corpora.Dictionary(some_corpus)
  mapped_corpus = [dictionary.doc2bow(text)
                   for text in some_corpus]
  
  tfidf = models.TfidfModel(mapped_corpus)
  </code></pre>
  
  <p>Now I'd like to apply thresholds to remove terms that appear too frequently (max_df) and too infrequently (min_df).  I know that scikit's CountVectorizer allows you to do this, but I can't seem to find how to set these thresholds in gensim's tfidf.  Could someone please help? </p>