title: python using random.shuffle() on only part of a list
body: <p>I am trying to implement a genetic algorithm in python. I have a list of 100 objects, sorted, and I need to access the top 30 plus 20 random others. My method is:</p>
  <pre><code>random.shuffle(list[30:])  #keep top 30, shuffle the rest
  for x in range (50):
      list[x].do_stuff
  </code></pre>
  <p>This doesn't work, the list is unchanged. Is my syntax wrong or is my entire method impossible?
  thanks</p>