title: HeatMap or ColumnChart ideas for multi-category datetime data
body: <p>I want to create a chart like the pic below
  <a href="https://i.stack.imgur.com/VPB46.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VPB46.jpg" alt="enter image description here"></a>
  Each point has x, value, cat1, cat2</p>
  
  <p>x-Axis to have DateTime data
  y-Axis can be Category cat1. I want cat2 as a sub category/ as an analogy it could be a highchart series </p>
  
  <p><strong>Please do not suggest to take cartesian product of cat1 cat2 and plot a single category because that crowds the chart and looses the functionality to select via cat2</strong></p>
  
  <p>Cat1 and cat2 are not related to each other. Just think of it as 2 enum tags to each data point. </p>
  
  <p>Ex for a daily cars sold data, Cat1 = [Hatchback, Sedan...], Cat2 = [Yellow, Red, Green] etc.. </p>
  
  <p>This is a very trivial usecase and I find it hard to believe that highchart cannot let me do it. i am sure I am missing something. Any examples or help would be highly appreciated since i have tried several approaches already now and spent considerable amount of time</p>
  
  <p><em>The idea is not to have a mixture of column series or heatmap series. i am ok with same type for all series, I personally would prefer a heatmap solution</em></p>