title: Change the values of a NumPy array that are NOT in a list of indices
body: <p>I have a NumPy array like:</p>
  
  <pre><code>a = np.arange(30)
  </code></pre>
  
  <p>I know that I can replace the values located at positions <code>indices=[2,3,4]</code> using for instance fancy indexing:</p>
  
  <pre><code>a[indices] = 999
  </code></pre>
  
  <p>But how to replace the values at the positions that are not in <code>indices</code>? Would be something like below?</p>
  
  <pre><code>a[ not in indices ] = 888
  </code></pre>