title: Multi-series bar chart in DC-js
body: <p>I'm using <a href="https://github.com/dc-js/dc.js" rel="noreferrer">DC.js</a> ( lib on top of D3 ) and have a great example of a single series bar chart:</p>
  
  <p><img src="https://i.stack.imgur.com/ssFr3.png" alt="enter image description here"></p>
  
  <pre><code> var xf = crossfilter(data);
   var dim = xf.dimension(function (d) { return d["EmployeeName"]; });
   var group = dim.group().reduceSum(function (d) { return d["AverageSale"]; });
  
   var chart = dc.barChart(elm);
   chart.barPadding(0.1)
   chart.outerPadding(0.05)
   chart.brushOn(false)
   chart.x(d3.scale.ordinal());
   chart.xUnits(dc.units.ordinal);
   chart.elasticY(true);
  
   chart.dimension(dim).group(group);
   chart.render();
  </code></pre>
  
  <p>but I was wondering if it was possible to create a multi dimensional bar chart using this library.  For example: Group by Store Name then Group By Employee then y-axis display average sale value ( already calculated by my backend ).</p>
  
  <p>The data looks like:</p>
  
  <pre><code> [{
      "EmployeeName": "Heather",
      "StoreName" : "Plaza",
      "AverageSaleValue": 200
   }{
      "EmployeeName": "Mellisa",
      "StoreName" : "Plaza",
      "AverageSaleValue": 240
   }, {
      "EmployeeName": "Sarah",
      "StoreName" : "Oak Park",
      "AverageSaleValue": 300
   } ... ]
  </code></pre>