title: Make contour of scatter
body: <p>In python, If I have a set of data </p>
  
  <pre><code>x, y, z
  </code></pre>
  
  <p>I can make a scatter with</p>
  
  <pre><code>import matplotlib.pyplot as plt
  plt.scatter(x,y,c=z)
  </code></pre>
  
  <p>How I can get a <code>plt.contourf(x,y,z)</code> of the scatter ? </p>