D3 Concentric/Nested Donut Chart

Question

I have created a donut chart with D3 that uses two data sets and displays slightly different size rings for each. I would like to add labels to the data set(for a legend), but the selectAll("path") expects each data set to be a simple array of values, so I have been unable to add the labels.

Below is the code I have so far and a fiddle:

Fiddle

    var dataset = {
      apples: [13245, 28479, 11111, 11000, 3876],
      oranges: [53245, 28479, 19697, 24037, 19654],
    };

    var width  = d3.select('#duration').node().offsetWidth,
        height = 300,
        cwidth = 33;

    var colorO = ['#1352A4', '#2478E5', '#5D9CEC', '#A4C7F4', '#DBE8FB'];
    var colorA = ['#58A53B', '#83C969', '#A8D996', '#CDE9C3', '#E6F4E1'];

    var pie = d3.layout.pie()
        .sort(null);

    var arc = d3.svg.arc();

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

    var gs = svg.selectAll("g").data(d3.values(dataset)).enter().append("g");
    var path = gs.selectAll("path")
        .data(function(d, i) { return pie(d); })
        .enter().append("path")
        .attr("fill", function(d, i, j) {
            if (j == 0) {

                return colorO[i];

            } else {

                return colorA[i];

            }

        })
        .attr("d", function(d, i, j) {
            if (j == 0) {

                return arc.innerRadius(75 + cwidth * j - 17).outerRadius(cwidth * (j + 2.9))(d);

            } else {

                return arc.innerRadius(75 + cwidth * j - 5).outerRadius(cwidth * (j + 2.5))(d);

            }


        });

Answer 1

expects each data set to be a simple array of values

This is not true. You can and should use an array of objects. Then use the value accessor to target a property of your object for the pie function. Here's how I'd re-factor your code:

        var dataset = {
          apples: [{
            value: 13245,
            color: '#1352A4',
            label: 'one'
          }, {
            value: 28479,
            color: '#5D9CEC',
            label: 'two'
          }, {
            value: 11111,
            color: '#1352A4',
            label: 'three'
          }, {
            value: 11000,
            color: '#A4C7F4',
            label: 'four'
          }, {
            value: 3876,
            color: '#DBE8FB',
            label: 'five'
          }],
          oranges: [{
            value: 53245,
            color: '#58A53B',
            label: 'one'
          }, {
            value: 28479,
            color: '#83C969',
            label: 'two'
          }, {
            value: 19697,
            color: '#A8D996',
            label: 'three'
          }, {
            value: 24037,
            color: '#CDE9C3',
            label: 'four'
          }, {
            value: 19654,
            color: '#E6F4E1',
            label: 'five'
          }]
        };

        var width = d3.select('#duration').node().offsetWidth,
          height = 300,
          cwidth = 33;

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

        var innerArc = d3.svg.arc()
          .innerRadius(58)
          .outerRadius(cwidth * 2.9);

        var outerArc = d3.svg.arc()
          .innerRadius(70 + cwidth)
          .outerRadius(cwidth * 3.5);

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

        var gs = svg.selectAll("g").data(d3.values(dataset)).enter().append("g");
        var en = gs.selectAll("path")
          .data(function(d, i) {
            return pie(d);
          })
          .enter();

        en.append("path")
          .attr("fill", function(d) {
            return d.data.color;
          })
          .attr("d", function(d, i, j) {
            return j === 0 ? innerArc(d) : outerArc(d);
          });

        en.append("text")
          .text(function(d) {
            return d.data.label;
          })
          .attr("transform", function(d, i, j) {
            return j === 0 ? "translate(" + innerArc.centroid(d) + ")" : "translate(" + outerArc.centroid(d) + ")";
          });

<script src="https://d3js.org/d3.v3.min.js"></script> 
<div id="duration">
    <svg style="height:300px;width:100%"></svg>
</div>