title: pandas - stacked bar chart with timeseries data
body: <p>I'm trying to create a stacked bar chart in pandas using time series data:</p>
  
  <pre><code>        DATE        TYPE    VOL
      0   2010-01-01  Heavy   932.612903
      1   2010-01-01  Light   370.612903
      2   2010-01-01  Medium  569.451613
      3   2010-02-01  Heavy   1068.250000
      4   2010-02-01  Light   341.535714
      5   2010-02-01  Medium  484.250000
      6   2010-03-01  Heavy   1090.903226
      7   2010-03-01  Light   314.419355
  </code></pre>
  
  <p>X = date, Y = vol, stacks = type</p>
  
  <p>any help greatly appreciated, thankyou.</p>