title: Numpy Indexing: Return the rest
body: <p>A simply example of numpy indexing:</p>
  
  <pre><code>In: a = numpy.arange(10)
  In: sel_id = numpy.arange(5)
  In: a[sel_id]
  Out: array([0,1,2,3,4])
  </code></pre>
  
  <p>How do I return the rest of the array that are not indexed by sel_id?  What I can think of is:</p>
  
  <pre><code>In: numpy.array([x for x in a if x not in a[id]])
  out: array([5,6,7,8,9])
  </code></pre>
  
  <p>Is there any easier way?    </p>