title: Decrease array size by averaging adjacent values with numpy
body: <p>I have a large array of thousands of vals in numpy. I want to decrease its size by averaging adjacent values.
  For example:</p>
  
  <pre><code>a = [2,3,4,8,9,10]
  #average down to 2 values here
  a = [3,9]
  #it averaged 2,3,4 and 8,9,10 together
  </code></pre>
  
  <p>So, basically, I have n number of elements in array, and I want to tell it to average down to X number of values, and it averages like above.</p>
  
  <p>Is there some way to do that with numpy (already using it for other things, so I'd like to stick with it).</p>