title: Scikit-learn confusion matrix
body: <p>I can't figure out if I've setup my binary classification problem correctly. I labeled the positive class 1 and the negative 0. However It is my understanding that by default scikit-learn uses class 0 as the positive class in its confusion matrix (so the inverse of how I set it up). This is confusing to me. Is the top row, in scikit-learn's default setting, the positive or negative class?
  Lets assume the confusion matrix output:</p>
  
  <pre><code>confusion_matrix(y_test, preds)
   [ [30  5]
      [2 42] ]
  </code></pre>
  
  <p>How would it look like in a confusion matrix? Are the actual instances the rows or the columns in scikit-learn? </p>
  
  <pre><code>          prediction                        prediction
             0       1                          1       0
           -----   -----                      -----   -----
        0 | TN   |  FP        (OR)         1 |  TP  |  FP
  actual   -----   -----             actual   -----   -----
        1 | FN   |  TP                     0 |  FN  |  TN
  </code></pre>