title: Hierarchical Dirichlet Process Gensim topic number independent of corpus size
body: <p>I am using the Gensim HDP module on a set of documents. </p>
  
  <pre><code>&gt;&gt;&gt; hdp = models.HdpModel(corpusB, id2word=dictionaryB)
  &gt;&gt;&gt; topics = hdp.print_topics(topics=-1, topn=20)
  &gt;&gt;&gt; len(topics)
  150
  &gt;&gt;&gt; hdp = models.HdpModel(corpusA, id2word=dictionaryA)
  &gt;&gt;&gt; topics = hdp.print_topics(topics=-1, topn=20)
  &gt;&gt;&gt; len(topics)
  150
  &gt;&gt;&gt; len(corpusA)
  1113
  &gt;&gt;&gt; len(corpusB)
  17
  </code></pre>
  
  <p>Why is the number of topics independent of corpus length?</p>