text: Exploring a corpus
  ==================
  
  A corpus is a set of documents.
  
  Below is a way of exploring unique tokens of a corpus,
  namely the `Heap's Law <http://en.wikipedia.org/wiki/Heaps%27_law>`_.
  
  .. literalinclude:: corpus.py
      :language: python
  
  - heap.png:
      .. image:: heap.png
          :width: 100%
  
  But why is our image not log-function shaped, as generally known?
  That is because the corpus we used is very small, and contains only 10 documents.
  To observe the Heap's law's log-function formatted curve,
  try experimenting with a larger corpus.
  Below is an image drawn from 1,000 Korean news articles.
  Of course, the curve will become smoother with a much larger corpus.
  
  - heap-1000.png:
      .. image:: heap-1000.png
          :width: 100%
  