title: Element-wise addition of two lists of different lengths?
body: <p>How to perform element-wise addition of different length lists?<br>
  Assuming "0" for missing elements.<br>
  Note: len(a) will always be less than or equal to len(b)</p>
  
  <p>example:</p>
  
  <pre><code>a=[1,2,3]
  b=[1,2,3,4,5]
  </code></pre>
  
  <p>Desired result:</p>
  
  <pre><code>result=[2,4,6,4,5]
  </code></pre>
  
  <p>I can almost, but not quite do this with:</p>
  
  <pre><code>result=[sum(n) for n in zip(a,b)]
  </code></pre>
  
  <p>Is it possible to automatically append '0' elements to (list a) so it is the same length as (list b), prior to doing the zip? If that is a good pythonic solution, how would one do that?</p>