title: Is there a SUMIF function to sum across identifiers in a dictionary in Python?
body: <p>Sorry if this is too simple a question, but is there a <code>sumif</code> function in python that will <code>sum</code> by identifier and category?  So in this case, I would like to have a function <code>sumif</code> which takes as arguments the identifier and the year and sums the amount.  For example <code>sumif('105','2006')</code> should return <code>1200</code>.</p>
  
  <pre><code>data = {'105':[{'2005': 500}, {'2005', 13000}, {'2006', 100}, {'2006', 200}, {'2006', 900}], '256': [{'2005', 5000}, {'2005', 800}]}
  </code></pre>