title: Extract a subset of data from numpy array
body: <p>I have a 2D numpy array that I need to extract a subset of data from where the value of the 2nd column is higher than a certain value.  What's the best way to do this?</p>
  <p>E.g. given the array:</p>
  <pre><code>array1 = [[1, 5], [2, 6], [3, 7], [4, 8]]
  </code></pre>
  <p>I would want to extract all rows where the 2nd column was higher than 6, so I'd get:</p>
  <pre><code>[3, 7], [4, 8]
  </code></pre>