title: Find indexes of matching rows in two 2-D arrays
body: <p>Suppose that I have two 2-D arrays as follows:</p>
  
  <pre><code>array([[3, 3, 1, 0],
         [2, 3, 1, 3],
         [0, 2, 3, 1],
         [1, 0, 2, 3],
         [3, 1, 0, 2]], dtype=int8)
  
  array([[0, 3, 3, 1],
         [0, 2, 3, 1],
         [1, 0, 2, 3],
         [3, 1, 0, 2],
         [3, 3, 1, 0]], dtype=int8)
  </code></pre>
  
  <p>Some rows in each array have a corresponding row that matches by value (but not necessarily by index) in the other array, and some don't.</p>
  
  <p>I would like to find an efficient way to return pairs of indexes in the two arrays that correspond to matching rows. If they were to be tuples I would expect to return</p>
  
  <pre><code>(0,4)
  (2,1)
  (3,2)
  (4,3)
  </code></pre>