title: matplotlib. How do I switch between subplots, rather than replotting them from scratch?
body: <p>I create a figure and fill it with a couple of subplots.</p>
  
  <p>As new data arrives, I'd like to draw it on a given subplot.</p>
  
  <p>How do I switch between subplots so that I don't have to create new subplot objects each time?</p>
  
  <p>Example:</p>
  
  <pre><code>from matplotlib.pyplot import figure,
  
  figure()
  subplot(2,1,1)
  subplot(2,1,2)
  
  # now go back and plot something on subplot 1 ...?
  </code></pre>