title: Remove values in 1d array contained in another array
body: <p>I have a project wherein I have to remove activities from a certain array and store it in another array.</p>
  
  <p>For example:</p>
  
  <pre><code>select_act = [2]
  q_active = [2, 3]
  </code></pre>
  
  <p>The code I have so far looks like this:</p>
  
  <pre><code>for ele in select_act:
      new_q_active = numpy.delete(q_active, numpy.where(ele))
  print(new_q_active)
  
  Output: new_q_active = [3]
  </code></pre>
  
  <p>The objective is to delete elements in <code>q_active</code> if they're already in <code>select_act</code>. The code I have above works for the given example. But for, let's say, all activities in <code>q_active</code> are already in <code>select_act</code>, </p>
  
  <pre><code>q_active = [2, 3]
  select_act = [2, 3]
  </code></pre>
  
  <p>The <code>output</code> I keep getting remains the same where it should be:</p>
  
  <pre><code>new_q_active = []
  </code></pre>
  
  <p>Any suggestion why I keep getting that? Any help would be appreciated! Thank you!</p>