title: matplotlib color gradient in patches?
body: <p>I'd like to create ellipses in matplotlib with a fill color that has an alpha (opacity) value that depends on the radius;</p>
  
  <p>e.g., a 2D Gaussian.  </p>
  
  <blockquote>
    <p>Is there any way to do this?</p>
  </blockquote>
  
  <p>It is possible to create rectangular plots with color gradients easily enough (like <a href="https://stackoverflow.com/questions/5296335/gradient-facecolor-matplotlib-bar-plot">Gradient facecolor matplotlib bar plot</a> and <a href="http://matplotlib.sourceforge.net/examples/pylab_examples/gradient_bar.html" rel="noreferrer">this</a>) but I can't figure out how to do the same for circles/ellipses.</p>