title: How to remove quiver arrows at all when values are zeros
body: <p>I have a large image and do sth like this:</p>
  
  <pre><code>test = np.zeros((800,800))
  quiver_v = np.zeros((2,800,800))
  quiver_v[0, 300,300] = 10
  
  plt.imshow(test)
  plt.quiver(quiver_v[0],quiver_v[1], scale_units='xy', angles='xy', scale=0.1, width=0.001, color='red') 
  
  plt.show()
  </code></pre>
  
  <p>I get the following <a href="https://i.stack.imgur.com/Buodx.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Buodx.png" alt="image"></a>.</p>
  
  <p>How can I set the background to "white" or rather how to avoid drawing anything for the quiver when values are zero?</p>