title: numpy divide row by row sum
body: <p>How can I divide a numpy array row by the sum of all values in this row?</p>
  
  <p>This is one example. But I'm pretty sure there is a fancy and much more efficient way of doing this:</p>
  
  <pre><code>import numpy as np
  e = np.array([[0., 1.],[2., 4.],[1., 5.]])
  for row in xrange(e.shape[0]):
      e[row] /= np.sum(e[row])
  </code></pre>
  
  <p>Result:</p>
  
  <pre><code>array([[ 0.        ,  1.        ],
         [ 0.33333333,  0.66666667],
         [ 0.16666667,  0.83333333]])
  </code></pre>