title: Plotting shaded uncertainty region in line plot in matplotlib when data has NaNs
body: <p>I would like a plot which looks like this:
  <a href="https://i.stack.imgur.com/pDYIh.png" rel="noreferrer"><img src="https://i.stack.imgur.com/pDYIh.png" alt="plot with uncertainty"></a></p>
  
  <p>I am trying to do this with matplotlib:</p>
  
  <pre><code>fig, ax = plt.subplots()
  
  with sns.axes_style("darkgrid"):
      for i in range(5):
          ax.plot(means.ix[i][list(range(3,104))], label=means.ix[i]["label"])
          ax.fill_between(means.ix[i][list(range(3,104))]-stds.ix[i][list(range(3,104))], means.ix[i][list(range(3,104))]+stds.ix[i][list(range(3,104))])
      ax.legend()
  </code></pre>
  
  <p>I want the shaded region to be the same colour as the line in the centre. But right now, my problem is that <code>means</code> has some <code>NaN</code>s and <code>fill_between</code> does not accept that. I get the error</p>
  
  <blockquote>
    <p>TypeError: ufunc 'isfinite' not supported for the input types, and the
    inputs could not be safely coerced to any supported types according to
    the casting rule ''safe''</p>
  </blockquote>
  
  <p>Any ideas on how I could achieve what I want? The solution doesn't need to use matplotlib as long as it can plot my series of points with their uncertainties for multiple series. </p>