title: transforming a numpy array
body: <p>I have a numpy array of this form</p>
  
  <pre><code>[[-0.77947021  0.83822138]
  [ 0.15563491  0.89537743]
  [-0.0599077  -0.71777995]
  [ 0.20759636  0.75893338]]
  </code></pre>
  
  <p>I want to create numpy array of this form <code>[x1, x2, x1*x2]</code> where <code>[x1, x2]</code> are from the original array list.</p>
  
  <p>At the moment I am creating a list of list using python code, then converting it to numpy array. But I think there might be a better way to do this.  </p>