title: Change Y axis tick formatters in Python Matplotlib
body: <p>I have a graph over </p>
  
  <pre><code>[1,2,3,4,5] 
  </code></pre>
  
  <p>with values that are quite small:</p>
  
  <pre><code>[0.000001,0.000002,...]
  </code></pre>
  
  <p>When I plot this, it shows the y axis ticks with the whole decimal. I would like something like </p>
  
  <pre><code>[1e-6,2e-6...]
  </code></pre>
  
  <p>to pop up instead. How can I do that?</p>