title: Python list comprehension for Numpy
body: <p>I'm looking for list-comprehension method or similar in Numpy to eliminate use of a for-loop eg. index_values is a Python dictionary list of lists (each list containing a different number of index values) and s is a numpy vector:</p>
  
  <pre><code>for i in range(33):
      s[index_values[i]] += 4.1
  </code></pre>
  
  <p>Is there a method available that allows eliminating the for-loop?</p>