Donut Chart Small Multiples by curran

A small multiples visualization of donut charts showing the breakdown of religions for the largest 5 countries. This is example 31 from the screencast Splitting Charts.

Note that area is not proportional to population, because the donuts are all the same size, regardless of population. This visualization shows the proportions of different religions within each country only. This property makes this visualization misleading in a way. For example, Brazil gets just as many pixels as China while being only a fraction of the population. To remedy this, it would be better to size each donut chart based on the population of each country.

Data from Pew Research Center Global Religious Landscape data set
Uses d3-legend
Uses nested selections.

forked from curran‘s block: Polar Area Small Multiples

index.html

<!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: 21pt;
      }

      .axis path, .axis line {
        fill: none;
        stroke: #000;
        shape-rendering: crispEdges;
      }

      .color-legend text {
        font-family: 'Open Sans', sans-serif;
        font-size: 17pt;
      }

    </style>
  </head>
  <body>
    <script>

      var outerWidth = 960;
      var outerHeight = 500;
      var margin = { left: 95, top: 0, right: 108, bottom: 297 };

      var xColumn = "country";
      var colorColumn = "religion";
      var sliceSizeColumn = "population";
      var outerRadius = 86;
      var innerRadius = outerRadius / 2;

      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 xAxisG = g.append("g")
        .attr("class", "x axis")
        .attr("transform", "translate(0," + innerHeight + ")");

      var colorLegendG = svg.append("g")
        .attr("class", "color-legend")
        .attr("transform", "translate(415, 255)");

      var xScale = d3.scale.ordinal().rangePoints([0, innerWidth]);
      var colorScale = d3.scale.category10();

      var xAxis = d3.svg.axis().scale(xScale).orient("bottom")
        .outerTickSize(0);

      var pie = d3.layout.pie();
      var arc = d3.svg.arc();
      arc.outerRadius(outerRadius);
      arc.innerRadius(innerRadius);

      var colorLegend = d3.legend.color()
        .scale(colorScale)
        .shapePadding(3)
        .shapeWidth(25)
        .shapeHeight(25)
        .labelOffset(4);

      function render(data){

        var nested = d3.nest()
          .key(function (d){ return d[xColumn]; })
          .entries(data);

        xScale.domain(nested.map( function (d){ return d.key; }));
        colorScale.domain(nested[0].values.map(function (d){ return d[colorColumn]; }));
        pie.value(function(d) { return d[sliceSizeColumn]; });

        var pies = g.selectAll(".pie").data(nested);
        pies.enter().append("g").attr("class", "pie");
        pies.attr("transform", function (d){
          var x = xScale(d.key);
          return "translate(" + x + "," + innerHeight / 2 + ")";
        });
        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();

        xAxisG.call(xAxis);
        colorLegendG.call(colorLegend);
      }

      function type(d){
        d.name = "World";
        d.population = +d.population;
        return d;
      }

      d3.csv("religionByCountryTop5.csv", type, render);

    </script>
  </body>
</html>

religionByCountryTop5.csv

country,religion,population
China,Christian,68410000
China,Muslim,24690000
China,Unaffiliated,700680000
China,Hindu,20000
China,Buddhist,244130000
China,Folk Religions,294320000
China,Other Religions,9080000
China,Jewish,0
India,Christian,31130000
India,Muslim,176190000
India,Unaffiliated,870000
India,Hindu,973750000
India,Buddhist,9250000
India,Folk Religions,5840000
India,Other Religions,27560000
India,Jewish,10000
USA,Christian,243060000
USA,Muslim,2770000
USA,Unaffiliated,50980000
USA,Hindu,1790000
USA,Buddhist,3570000
USA,Folk Religions,630000
USA,Other Religions,1900000
USA,Jewish,5690000
Indonesia,Christian,23660000
Indonesia,Muslim,209120000
Indonesia,Unaffiliated,240000
Indonesia,Hindu,4050000
Indonesia,Buddhist,1720000
Indonesia,Folk Religions,750000
Indonesia,Other Religions,340000
Indonesia,Jewish,0
Brazil,Christian,173300000
Brazil,Muslim,40000
Brazil,Unaffiliated,15410000
Brazil,Hindu,0
Brazil,Buddhist,250000
Brazil,Folk Religions,5540000
Brazil,Other Religions,300000
Brazil,Jewish,110000