title: Using negative values in a matplotlib's bar plot
body: <p>Starting with this <a href="http://matplotlib.org/examples/pylab_examples/bar_stacked.html" rel="nofollow">example</a>, I would like to do something very similar but being able to use negative values for variables in the code, for example;</p>
  
  <pre><code>menMeans   = (-20, 35, -30, 35, -27)
  womenMeans = (25, -32, 34, -20, 25)
  </code></pre>
  
  <p>, although this has nothing to do with the men/women meaning. But when I do this, I can not see anything related with negative values in the plot. I also change Y scale;</p>
  
  <pre><code>plt.yticks(np.arange(-81,81,10))
  </code></pre>
  
  <p>but nothing. Any hints?</p>