title: How to compare elements and remove those not complying with condition
body: <p>I'd like to compare elements of one row with the elements of the next row of a numpy array. More precisely </p>
  
  <pre><code>a=np.array([[1,2,3],[10,12,13],[20,23,24],[45,46,49],[51,52,53]])
  </code></pre>
  
  <p>I know I can have the differences using </p>
  
  <pre><code>np.diff(a,axis=0)
  </code></pre>
  
  <p>which returns:</p>
  
  <pre><code>array([[ 9, 10, 10],
     [10, 11, 11],
     [25, 23, 25],
     [ 6,  6,  4]])
  </code></pre>
  
  <p>But how can I get the initial 'a' array without elements that have a difference &lt;=10 with the next row. Particularly, the difference in the third column.
  The array I'd like to get is;</p>
  
  <pre><code>array([[1,2,3],[20,23,24],[45,46,49]])
  </code></pre>
  
  <p>I'm pretty sure there is an (easy) way to do it with numpy. Maybe with <code>np.where</code>?</p>