title: Permutation without duplicates in Python
body: <p>I have N positions, and each position can be either 0 or 1. I have fixed number of 1s, and I want to permutate these fixed number of 1s in these N positions.</p>
  
  <pre><code>from itertools import permutations
  p = [0 for k in xrange(6)]
  for k in xrange(0,3):
          p[k] = 1
  print(list(permutations(p)))
  </code></pre>
  
  <p>But above result contains four [0,0,0,1,1,1] in the list. I only want one of them. How can I get rid of these duplicates?  </p>