title: Finding a numpy mode vector
body: <p>I have a numpy array of one-hot vectors.  I want to find the mode of these one-hot vectors.  Note that this is not equivalent to finding the mode over the values.</p>
  
  <p>e.g. for </p>
  
  <pre><code>x = [[0,0,0,1],
       [0,0,0,1],
       [0,0,1,0],
       [0,1,0,0],
       [1,0,0,0]]
  
  assert vector_mode(x) == [0,0,0,1]
  assert scipy.stats.mode(x) == [0,0,0,0]
  </code></pre>
  
  <p>What is the most efficient way to do this with numpy/scipy?</p>