title: Removing punctuation/numbers from text problem
body: <p>I had some code that worked fine removing punctuation/numbers using regular expressions in python, I had to change the code a bit so that a stop list worked, not particularly important. Anyway, now the punctuation isn't being removed and quite frankly i'm stumped as to why.</p>
  
  <pre><code>import re
  import nltk
  
  # Quran subset
  filename = raw_input('Enter name of file to convert to ARFF with extension, eg. name.txt: ')
  
  # create list of lower case words
  word_list = re.split('\s+', file(filename).read().lower())
  print 'Words in text:', len(word_list)
  # punctuation and numbers to be removed
  punctuation = re.compile(r'[-.?!,":;()|0-9]')
  for word in word_list:
      word = punctuation.sub("", word)
  print word_list
  </code></pre>
  
  <p>Any pointers on why it's not working would be great, I'm no expert in python so it's probably something ridiculously stupid. Thanks.</p>