title: Using pandas to plot barplots with error bars
body: <p>I'm trying to generate bar plots from a DataFrame like this:</p>
  
  <pre><code>            Pre    Post
   Measure1   0.4    1.9
  </code></pre>
  
  <p>These values are median values I calculated from elsewhere, and I have also their variance and standard deviation (and standard error, too). I would like to plot the results as a bar plot with the proper error bars, but specifying more than one error value to <code>yerr</code> yields an exception:</p>
  
  <pre><code># Data is a DataFrame instance
  fig = data.plot(kind="bar", yerr=[0.1, 0.3])
  
  [...]
  ValueError: In safezip, len(args[0])=1 but len(args[1])=2
  </code></pre>
  
  <p>If I specify a single value (incorrect) all is fine. How can I actually give each column its correct error bar?</p>