title: Counting phrase frequency in Python 3.3.2
body: <p>I have been examining different sources on the web and have tried various methods but could only find how to count the frequency of unique words but not unique phrases. The code I have so far is as follows:</p>
  
  <pre><code>import collections
  import re
  wanted = set(['inflation', 'gold', 'bank'])
  cnt = collections.Counter()
  words = re.findall('\w+', open('02.2003.BenBernanke.txt').read().lower())
  for word in words:
      if word in wanted:
          cnt [word] += 1
  print (cnt)
  </code></pre>
  
  <p>If possible, I would also like to count the number of times the phrases 'central bank' and 'high inflation' is used in this text. I appreciate any suggestion or guidance you can give.</p>