title: How to replace values in a numpy array based on another column?
body: <p>Let say i have the following:</p>
  
  <pre><code>import numpy as np
  
  data = np.array([
       [1,2,3],
       [1,2,3],
       [1,2,3],
       [4,5,6],         
       ])
  </code></pre>
  
  <p>How would I go about changing values in column 3 based on values in column 2?  For instance, If column 3 == 3, column 2 = 9.  </p>
  
  <pre><code>[[1,9,3],
   [1,9,3],
   [1,9,3],
   [4,5,6]]
  </code></pre>
  
  <p>I've looked at <code>np.any()</code>, but I can't figure out how to alter the array in place.</p>