title: How to normalize in numpy?
body: <p>I have the following question: A numpy array Y of shape (N, M) where Y[i] contains the same data as X[i], but normalized to have mean 0 and standard deviation 1.
  I have mapped the array like this:</p>
  <pre><code>(X - np.mean(X)) / np.std(X) 
  </code></pre>
  <p>but it doesn't give me the correct answer.</p>