title: Numpy standard deviation not working for me
body: <p>Where I am going wrong with this <code>for</code> loop which is meant to take as input a specific corpus, sample size and number of samples and then give the average and standard deviation of expected no. of sentiment tokens?</p>
  
  <pre><code>def test_iterate(corpus_reader, sample_size, number_of_samples):
  for i in xrange(number_of_samples):
      tokens = corpus_reader.sample_words_by_sents(sample_size)
      sents = corpus_reader.sample_sents(sample_size)
      print expected_sentiment_tokens(tokens)
      s = []
      s.append(expected_sentiment_tokens(tokens))
      s = array(s)
  print "Average expected no of sentiment tokens: %s" % average(s)
  print "Standard deviation of sentiment tokens: %s" % std(s)
  
  test_iterate(rcr, 500, 3)
  </code></pre>
  
  <p>returns</p>
  
  <pre><code>181.166666667
  186.277777778
  185.5
  Average expected no of sentiment tokens: 185.5
  Standard deviation of sentiment tokens: 0.0
  </code></pre>
  
  <p>For some reason the average is being set to the last sample instead of averaging and standard deviating all of the samples together.</p>