title: Slicing arrays with lists
body: <p>So, I create a numpy array:</p>
  
  <p><code>a = np.arange(25).reshape(5,5)</code></p>
  
  <blockquote>
    <p>array([[ 0,  1,  2,  3,  4],
          [ 5,  6,  7,  8,  9],
          [10, 11, 12, 13, 14],
          [15, 16, 17, 18, 19],
          [20, 21, 22, 23, 24]])</p>
  </blockquote>
  
  <p>A conventional slice <code>a[1:3,1:3]</code> returns</p>
  
  <blockquote>
    <p>array([[ 6,  7],
          [11, 12]])</p>
  </blockquote>
  
  <p>as does using a list in the second <code>a[1:3,[1,2]]</code></p>
  
  <blockquote>
    <p>array([[ 6,  7],
          [11, 12]])</p>
  </blockquote>
  
  <p>However, <code>a[[1,2],[1,2]]</code> returns</p>
  
  <blockquote>
    <p>array([ 6, 12])</p>
  </blockquote>
  
  <p>Obviously I am not understanding something here.  That said, slicing with a list might on occasion be very useful.</p>
  
  <p>Cheers,</p>
  
  <p>keng</p>