title: FutureWarning: in the future, boolean array-likes will be handled as a boolean array index
body: <p>I am trying to evaluate the following expression</p>
  
  <pre><code>X_r[y_all == "yes", 0]
  </code></pre>
  
  <p>and get the following error:</p>
  
  <blockquote>
    <p>/usr/local/lib/python2.7/dist-packages/ipykernel/<strong>main</strong>.py:1:
    FutureWarning: in the future, boolean array-likes will be handled as a
    boolean array index</p>
  </blockquote>
  
  <p>What does it mean? I do WISH to use <code>y_all=="yes"</code> as boolean array index. Since it is warning me, it does something else.</p>
  
  <p>What does it do?</p>
  
  <p><strong>P.S.</strong></p>
  
  <pre><code>&gt; np.shape(X_r)
  (395, 2)
  
  &gt; type(X_r)
  numpy.ndarray
  </code></pre>