title: draw a smooth polygon around data points in a scatter plot, in matplotlib
body: <p>I have a bunch of cross plots with two sets of data and have been looking for a matploltib way of highlighting their plotted regions with smoothed polygon outlines.</p>
  
  <p>At the moment i just use Adobe Illustrator and amend saved plot, but this is not ideal. Example:<img src="https://i.stack.imgur.com/dNHeg.png" alt="enter image description here"></p>
  
  <p>I'd be grateful for any pointers/links to examples. </p>
  
  <p>Cheers</p>