title: Removing elements from an array that are in another array
body: <p>Say I have these 2D arrays <code>A</code> and <code>B</code>.</p>
  <p>How can I remove elements from <code>A</code> that are in <code>B</code>. (Complement in set theory: A-B)</p>
  <pre><code>A=np.asarray([[1,1,1], [1,1,2], [1,1,3], [1,1,4]])
  B=np.asarray([[0,0,0], [1,0,2], [1,0,3], [1,0,4], [1,1,0], [1,1,1], [1,1,4]])
  #output = [[1,1,2], [1,1,3]]
  </code></pre>
  <hr />
  <p>To be more precise, I would like to do something like this.</p>
  <pre><code>data = some numpy array
  label = some numpy array
  A = np.argwhere(label==0) #[[1 1 1], [1 1 2], [1 1 3], [1 1 4]]
  B = np.argwhere(data&gt;1.5) #[[0 0 0], [1 0 2], [1 0 3], [1 0 4], [1 1 0], [1 1 1], [1 1 4]]
  out = np.argwhere(label==0 and data&gt;1.5) #[[1 1 2], [1 1 3]]
  </code></pre>