title: Creating multiple column dimension from csv
body: <p>I'm trying to make a pie chart using multiple columns from a csv file, I can produce a pie chart but it only use the last value d.gre. What am I doing wrong?</p>
  
  <p>Code is below</p>
  
  <pre><code>d3.csv("elecVotes.csv", function (data) {
  
  var ndx = crossfilter(data);
  var partysDim = ndx.dimension(function(d) { return +d.rep, +d.dem, +d.lib, +d.ind, +d.gre;})
  var partys = partysDim.group();
  
  var pie = dc.pieChart('#chart-pie');
  
  pie
      .width(180)
      .height(180)
      .radius(80)
      .dimension(partysDim)
      .group(partys)
      .renderLabel(true)
      .innerRadius(10)
      .transitionDuration(500)
      .colorAccessor(function (d, i) { return d.value; });
  
      dc.renderAll();
  });
  </code></pre>
  
  <p>electVotes.csv</p>
  
  <p><code>state, rep,dem,lib,ind,gre 
  Alabama,1314431,725704,44211,20276,9341
  New York,5655,54444,65666,2355,12225
  Texas,4355,543234,12321,12331,45644</code></p>