title: Remove sequential NumPy array index in a loop over it's content
body: <p>I'm iterating over a NumPy (nd) array of OpenCV lines. I want to remove all lines which are outwith 8 degrees of vertical. I realise the numpy array is immutable and what I'm doing in the code is not right but it demonstrates the idea of what I'm trying to do;</p>
  
  <pre><code>index = 0
  for line in self.lines[0]:
      if (line[1]*180)/np.pi &gt; 8:                                      
          self.lines[0] = np.delete(self.lines[0], index, axis=0)
      index+=1
  </code></pre>
  
  <p>How can I go about removing these NumPy array indexes?</p>
  
  <p>Thanks!</p>