title: Draw ellipse based on data with matplotlib
body: <p>I'm trying to draw an ellipse on my plot in such a way to represent a cluster. 
  The code below here plots the first picture. It is within a for loop, but it is not important</p>
  
  <pre><code>native_f1 = [some values here]
  native_f2 = [some values here]
  
  ax = plt.subplot(2, 2, index)
  ax.scatter(native_f1, native_f2, s=40)
  axes = plt.gca()
  axes.set_xlim([min(native_f1) - 800, max(native_f1) + 800])
  axes.set_ylim([min(native_f2) - 800, max(native_f2) + 800])
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/nlQ3q.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/nlQ3q.png" alt="no ellipses"></a></p>
  
  <p>Now I'd like to obtain something like that:</p>
  
  <p><a href="https://i.stack.imgur.com/x3DbH.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/x3DbH.png" alt="enter image description here"></a></p>
  
  <p>How do I draw an ellipse based on the values that I use to plot these graphs ?
  Thank you</p>