title: Inserting rows of zeros at specific places along the rows of a NumPy array
body: <p>I have a two column numpy array. I want to go through each row of the 2nd column, and take the difference between each set of 2 numbers (9.6-0, 19.13-9.6, etc). If the difference is > 15, I want to insert a row of 0s for both columns. I really only need to end up with values in the first column (I only need the second to determine where to put 0s), so if it's easier to split them up that would be fine.</p>
  
  <p>This is my input array:</p>
  
  <pre><code> [[0.00 0.00]
   [1.85 9.60]
   [2.73 19.13]
   [0.30 28.70]
   [2.64 38.25]
   [2.29 47.77]
   [2.01 57.28]
   [2.61 66.82]
   [2.20 76.33]
   [2.49 85.85]
   [2.55 104.90]
   [2.65 114.47]
   [1.79 123.98]
   [2.86 133.55]]
  </code></pre>
  
  <p>and it should turn into:</p>
  
  <pre><code> [[0.00 0.00]
   [1.85 9.60]
   [2.73 19.13]
   [0.30 28.70]
   [2.64 38.25]
   [2.29 47.77]
   [2.01 57.28]
   [2.61 66.82]
   [2.20 76.33]
   [2.49 85.85]
   [0.00 0.00]
   [2.55 104.90]
   [2.65 114.47]
   [1.79 123.98]
   [2.86 133.55]]
  </code></pre>