title: confusion_matrix - too many values to unpack
body: <p>I'm trying to use the <a href="http://scikit-learn.org/stable/modules/generated/sklearn.metrics.confusion_matrix.html" rel="nofollow noreferrer">confusion_matrix</a> function, as follows:</p>
  
  <pre><code>tn, fp, fn, tp = confusion_matrix(y_true, y_predict).ravel()
  </code></pre>
  
  <p><code>y_true</code> and <code>y_predict</code> are both lists. When I return their shape, I get: <code>(71,)</code>.</p>
  
  <p>I'm however getting the following error for the above statement:</p>
  
  <pre><code>ValueError: too many values to unpack
  </code></pre>
  
  <p>I'm not sure if it is because of the second (empty) dimension in <code>(71,)</code>? I'm not sure how to remove it if it is the issue here.</p>
  
  <p>Any thoughts?</p>
  
  <p>Thanks.</p>