title: How to set size for scatter plot
body: <p>I have three lines setting a plot. I expect the size of the pic.png to be 640x640 pixels. But I got 800x800 picture. </p>
  
  <pre><code>plt.figure(figsize=(8, 8), dpi=80)
  plt.scatter(X[:],Y[:])
  plt.savefig('pic.png')
  </code></pre>
  
  <p>BTW I have no problem setting size with object-oriented interface but I need to use pyplot style.</p>