title: Use numpy setdiff1d keeping the order
body: <pre><code>a = np.array([1, 2, 3])
  b = np.array([4, 2, 3, 1, 0])
  c = np.setdiff1d(b, a)
  print("c", c)
  </code></pre>
  
  <p>The result is <code>c [0, 4]</code> but the answer I want is <code>c [4 0]</code>.</p>
  
  <p>How can I do that?</p>