D3 Examples - Polar Area

Polar Area
A small multiples visualization of polar area charts showing the breakdown of religions for the all countries. This is a variation derived from example 30 from the screencast Splitting Charts.
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<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>D3 Example</title>
    <script src="//cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
    <script src="//cdnjs.cloudflare.com/ajax/libs/d3-legend/1.1.0/d3-legend.js"></script>
    <link href='https://fonts.googleapis.com/css?family=Open+Sans' rel='stylesheet' type='text/css'>
    <style>
    
      .axis text {
        font-family: 'Open Sans', sans-serif;
        font-size: 20pt;
      }
​
      .axis path, .axis line {
        fill: none;
        stroke: #000;
        shape-rendering: crispEdges;
      }
​
      .color-legend text {
        font-family: 'Open Sans', sans-serif;
        font-size: 20pt;
      }
​
    </style>
  </head>
  <body>
    <script>
​
      var outerWidth = 960;
      var outerHeight = 500;
      var margin = { left: 87, top: 0, right: 297, bottom: 76 };
      var radiusMax = 143;
​
      var xColumn = "country";
      var colorColumn = "religion";
      var radiusColumn = "population";
      
      var clickedColorValue;
​
      var innerWidth  = outerWidth  - margin.left - margin.right;
      var innerHeight = outerHeight - margin.top  - margin.bottom;
​
      var svg = d3.select("body").append("svg")
        .attr("width",  outerWidth)
        .attr("height", outerHeight);
      var g = svg.append("g")
        .attr("transform", "translate(" + margin.left + "," + margin.top + ")");
​
      var colorLegendG = svg.append("g")
        .attr("class", "color-legend")
        .attr("transform", "translate(714, 40)");
​
      var xScale = d3.scale.ordinal().rangePoints([0, Math.PI * 2]);
      var radiusScale = d3.scale.sqrt().range([0, radiusMax]);
      var colorScale = d3.scale.category10();
​
      var pie = d3.layout.pie();
      var arc = d3.svg.arc();
​
      var colorLegend = d3.legend.color()
        .scale(colorScale)
        .shapePadding(3)
        .shapeWidth(40)
        .shapeHeight(40)
        .labelOffset(4);
​
      function render(data){
​
        var nested = d3.nest()
          .key(function (d){ return d[xColumn]; })
          .entries(data);
        
        nested.forEach(function (d){
          d.rank = d3.sum(d.values, function (d){
            if(d[colorColumn] === clickedColorValue){
              return d[radiusColumn];
            } else {
              return 0;
            }
          });
        })
        nested.sort(function (a, b){
          return b.rank - a.rank;
        });
​
        xScale.domain(nested.map( function (d){ return d.key; }));
        
        radiusScale.domain([
          0,
          d3.max(nested, function (xEntry){
            return d3.max(xEntry.values, function (d){
              return d[radiusColumn];
            });
          })
        ]);
        colorScale.domain(nested[0].values.map(function (d){
          return d[colorColumn];
        })); 
​
        pie.value(function (){ return 1; });
        arc.outerRadius(function(d) { 
          return radiusScale(d.data[radiusColumn]);
        });
​
        var pies = g.selectAll(".pie").data(nested, function (d){ return d.key; });
        pies.enter().append("g").attr("class", "pie");
        pies
          .transition()
          .duration(500)
          .delay(function(d, i) { return i * 3; })
          .attr("transform", function (d){
            var a = xScale(d.key);
            var x = innerHeight / 2 + Math.sin(a) * 150;
            var y = innerHeight / 2 + Math.cos(a) * 150;
           
          
            return "translate(" + x + "," + y + ")";
          });
        pies.exit().remove();
​
        var slices = pies.selectAll("path").data(function (d){
          return pie(d.values);
        });
​
        slices.enter().append("path");
        slices
          .attr("d", arc)
          .attr("fill", function (d){ return colorScale(d.data[colorColumn]); });
        slices.exit().remove(); 
​
        colorLegendG.call(colorLegend);
        listenForHover(colorLegendG.selectAll("rect"), data);
        listenForHover(colorLegendG.selectAll("text"), data);
      }
      
      function listenForHover(selection, data){
        selection
          .on("click", function (d){
            clickedColorValue = d;
            render(data);
          })
//           .on("mouseover", function (d){
//             hoveredColorValue = d;
//             render(data);
//           })
//           .on("mouseout", function (d){
//             hoveredColorValue = null;
//             render(data);
//           })
          .style("cursor", "pointer");
      }
​
      function type(d){
        d.name = "World";
        d.population = +d.population;
        return d;
      }
​
      d3.csv("religionByCountry.csv", type, render);
​
    </script>
  </body>
</html>
​
    