title: Scikit-learn : roc_auc_score
body: <p>I am using the roc_auc_score function from scikit-learn to evaluate my model performances.
  Howver, I get differents values whether I use predict() or predict_proba()</p>
  
  <pre><code>p_pred = forest.predict_proba(x_test)
  y_test_predicted= forest.predict(x_test)
  fpr, tpr, _ = roc_curve(y_test, p_pred[:, 1])
  roc_auc = auc(fpr, tpr)
  
  roc_auc_score(y_test,y_test_predicted) # = 0.68
  roc_auc_score(y_test, p_pred[:, 1])    # = 0.93
  </code></pre>
  
  <p>Could advise on that please ?</p>
  
  <p>Thanks in advance</p>