title: Filter array by unique item in list?
body: <p>I want filter list by unique item in sublist </p>
  
  <p>example:</p>
  
  <pre class="lang-py prettyprint-override"><code>#       ---------
  #       v       v
  lst = [[1, 0], [1, 1], [2, 2]]
  
  # result
  [[1, 0], [2, 2]]
  </code></pre>
  
  <p>I am using, want:</p>
  
  <pre class="lang-py prettyprint-override"><code>def setx0(arr):
     r = []
     filter(lambda x : r.append(x) if x[0] not in set(map(lambda x: x[0], r)) else False, arr)
     return r
  </code></pre>
  
  <p>a better way?</p>