title: numpy: reorder array by specified values
body: <p>I have a matrix:</p>
  
  <pre><code>A = [ [1,2],
        [3,4],
        [5,6] ]
  </code></pre>
  
  <p>and a vector of values:</p>
  
  <pre><code>V = [4,6,2]
  </code></pre>
  
  <p>I would like to reorder A by 2nd column, using values from V. The result should
  be:</p>
  
  <pre><code>A = [ [3,4],
        [5,6], 
        [1,2] ] # 2nd columns' values have the same order as V
  </code></pre>
  
  <p>How to do it?</p>