title: Color each errorbar with different color
body: <p>I'm trying to plot an <code>errorbar</code> graph where each error bar may be either, say, red or green depending on whether the statistics used to compute the bar are significant.<br>
  I tried using an array of colors as an input to the <code>c</code> parameter, but that didn't work.</p>
  
  <p>Does anyone know how to do that?</p>
  
  <p>Here is the code that I have so far:</p>
  
  <pre><code>yerrs = np.array([quantiles[:,2],quantiles[:,3]])
  print yerrs.shape
  colors = ['r', 'b'] * (yerrs.shape[1]/2)
  fig, axes = plt.subplots(nrows=2, sharex=True, sharey=True)
  axes[0].errorbar(quantiles[:,0],quantiles[:,1], yerr=yerrs, c=colors)
  axes[0].axhline(0, color='black')
  axes[0].axvline(0, color='black')
  axes[0].set_title('Fitted dist')
  </code></pre>
  
  <p>I then get the error:</p>
  
  <pre><code>ValueError: to_rgba: Invalid rgba arg "['r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b', 'r', 'b']"
  could not convert string to float: r
  </code></pre>