title: numpy array to permutation matrix
body: <pre><code>np.array([1,2,3])
  </code></pre>
  
  <p>I've got numpy array. I would like to turn it into a numpy array with tuples of each 1:1 permutation. Like this:</p>
  
  <pre><code>np.array([
      [(1,1),(1,2),(1,3)],
      [(2,1),(2,2),(2,3)],
      [(3,1),(3,2),(3,3)],
  ])
  </code></pre>
  
  <p>Any thoughts on how to do this efficiently? I need to do this operation a few million times.</p>