title: pythonic way for axis-wise winner-take-all in numpy
body: <p>I am wondering what the most concise and pythonic way to keep only the maximum element in each line of a 2D numpy array while setting all other elements to zeros. Example:</p>
  
  <p>given the following numpy array:</p>
  
  <pre><code>a = [ [1, 8, 3 ,6],
        [5, 5, 60, 1],
        [63,9, 9, 23] ]
  </code></pre>
  
  <p>I want the answer to be:</p>
  
  <pre><code>b = [ [0, 8, 0, 0],
        [0, 0, 60, 0],
        [63,0, 0, 0 ] ]
  </code></pre>
  
  <p>I can think of several ways to solve that, but what interests me is whether there are python functions to so this just quickly</p>
  
  <p>Thank you in advance</p>