title: How to make matplotlib clipping to work on plot generated by rbf
body: <p>I would like to use a patch on my plot to show only the points in a circle, the problem is that i am using an image generated with <code>Rbf</code> and it does not work.</p>
  
  <p>Here is the last code i tried :</p>
  
  <pre><code>from scipy import  interpolate
  import numpy as np
  import matplotlib.pyplot as plt
  import matplotlib.patches as patches
  
  
  x, y, z = 10 * np.random.random((3,10))
  xi, yi = np.linspace(x.min(), x.max(), 100), np.linspace(y.min(), y.max(), 100)
  xi, yi = np.meshgrid(xi, yi)
  
  rbf = interpolate.Rbf(x, y, z, function='linear')
  zi = rbf(xi, yi)
  
  fig1 = plt.figure(figsize=(4, 4), facecolor='white')
  ax = fig1.add_subplot(111)
  
  ax.imshow(zi, vmin=z.min(), vmax=z.max(), origin='lower',
             extent=[x.min(), x.max(), y.min(), y.max()])
  
  something = ax.scatter(x,y)
  
  patch = patches.Circle((1,1),radius=1,fc='none')
  ax.add_patch(patch)
  something.set_clip_path(patch)
  fig1.show()
  </code></pre>
  
  <p>I am getting the following result, as you can see the values are showed in the whole rectangle, not only in a circle:</p>
  
  <p><a href="https://i.stack.imgur.com/dIX5t.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dIX5t.png" alt="result"></a></p>