title: kilo (K) and mega (M) suffixes on matplotlib's axes
body: <p>I would like to print values on axes not as 30000 or 7000000 but as 30K or 7M. It means to add K (kilo) suffix for x &lt; 10^6 and M (mega) suffix for x >= 10^6. How can I do that?</p>
  
  <p>Current code snippet:</p>
  
  <pre><code>ax = pylab.gca()
  formatter = matplotlib.ticker.FormatStrFormatter('%.f')
  ax.xaxis.set_major_formatter(formatter)
  </code></pre>