title: numpy, Select elements in rows by 1d indexes array
body: <p>Let we have square array, n*n. For example, n=3 and array is this:</p>
  
  <pre><code>arr = array([[0, 1, 2],
     [3, 4, 5],
     [6, 7, 8]])
  </code></pre>
  
  <p>And let we have array of indices in the each ROW. For example:</p>
  
  <pre><code>myidx=array([1, 2, 1], dtype=int64)
  </code></pre>
  
  <p>I want to get:</p>
  
  <blockquote>
    <p>[1, 5, 7]</p>
  </blockquote>
  
  <p>Because in line [0,1,2] take element with index 1, in line [3,4,5] get element with index 2, in line [6,7,8] get element with index 1. </p>
  
  <p>I'm confused, and can't take elements this way using standard numpy indexing.
  Thank you for answer.</p>