title: Plot Multicolored line based on conditional in python
body: <p>I have a pandas dataframe with three columns and a datetime index</p>
  
  <pre><code>date        px_last  200dma     50dma           
  2014-12-24  2081.88 1953.16760  2019.2726
  2014-12-26  2088.77 1954.37975  2023.7982
  2014-12-29  2090.57 1955.62695  2028.3544
  2014-12-30  2080.35 1956.73455  2032.2262
  2014-12-31  2058.90 1957.66780  2035.3240
  </code></pre>
  
  <p>I would like to make a time series plot of the 'px_last' column that is colored green if on the given day the 50dma is above the 200dma value and colored red if the 50dma value is below the 200dma value. I have seen this example, but can't seem to make it work for my case
  <a href="http://matplotlib.org/examples/pylab_examples/multicolored_line.html" rel="noreferrer">http://matplotlib.org/examples/pylab_examples/multicolored_line.html</a></p>