donut.js

function draw(file) {
  var width = $('#chart').width();
  var height = $('#chart').height();
  var radius = Math.min(width, height) / 2;

  var color = d3.scale.ordinal()
      .range(colorbrewer.RdBu[9]);

  var arc = d3.svg.arc()
      .outerRadius(radius - 10)
      .innerRadius(radius - 70);

  var pie = d3.layout.pie()
      .sort(null)
      .value(function(d) { return d.population; });

  var svg = d3.select("#chart").append("svg")
      .attr("width", width)
      .attr("height", height)
    .append("g")
      .attr("transform", "translate(" + width / 2 + "," + height / 2 + ")");

  d3.csv(file, function(error, data) {
    data.forEach(function(d) {
      d.population = +d.population;
    });

    var g = svg.selectAll(".arc")
        .data(pie(data))
      .enter().append("g")
        .attr("class", "arc");

    g.append("path")
        .attr("d", arc)
        .style("fill", function(d) { return color(d.data.age); });

    g.append("text")
        .attr("transform", function(d) { return "translate(" + arc.centroid(d) + ")"; })
        .attr("dy", ".35em")
        .style("text-anchor", "middle")
        .text(function(d) { return d.data.age; });

  });
}