// From http://mkweb.bcgsc.ca/circos/guide/tables/

var chord = d3.layout.chord()

  .padding(.05)

  .sortSubgroups(d3.descending)

  .matrix([

    [11975,  5871, 8916, 2868],

    [ 1951, 10048, 2060, 6171],

    [ 8010, 16145, 8090, 8045],

    [ 1013,   990,  940, 6907]

  ]);

var w = 600,

    h = 600,

    r0 = Math.min(w, h) * .41,

    r1 = r0 * 1.1;

var fill = d3.scale.ordinal()

    .domain(d3.range(4))

    .range(["#000000", "#FFDD89", "#957244", "#F26223"]);

var svg = d3.select("#chart")

  .append("svg:svg")

    .attr("width", w)

    .attr("height", h)

  .append("svg:g")

    .attr("transform", "translate(" + w / 2 + "," + h / 2 + ")");

svg.append("svg:g")

  .selectAll("path")

    .data(chord.groups)

  .enter().append("svg:path")

    .style("fill", function(d) { return fill(d.index); })

    .style("stroke", function(d) { return fill(d.index); })

    .attr("d", d3.svg.arc().innerRadius(r0).outerRadius(r1))

    .on("mouseover", fade(.1))

    .on("mouseout", fade(1));

var ticks = svg.append("svg:g")

  .selectAll("g")

    .data(chord.groups)

  .enter().append("svg:g")

  .selectAll("g")

    .data(groupTicks)

  .enter().append("svg:g")

    .attr("transform", function(d) {

      return "rotate(" + (d.angle * 180 / Math.PI - 90) + ")"

          + "translate(" + r1 + ",0)";

    });

ticks.append("svg:line")

    .attr("x1", 1)

    .attr("y1", 0)

    .attr("x2", 5)

    .attr("y2", 0)

    .style("stroke", "#000");

ticks.append("svg:text")

    .attr("x", 8)

    .attr("dy", ".35em")

    .attr("text-anchor", function(d) {

      return d.angle > Math.PI ? "end" : null;

    })

    .attr("transform", function(d) {

      return d.angle > Math.PI ? "rotate(180)translate(-16)" : null;

    })

    .text(function(d) { return d.label; });

svg.append("svg:g")

    .attr("class", "chord")

  .selectAll("path")

    .data(chord.chords)

  .enter().append("svg:path")

    .style("fill", function(d) { return fill(d.target.index); })

    .attr("d", d3.svg.chord().radius(r0))

    .style("opacity", 1);

/** Returns an array of tick angles and labels, given a group. */

function groupTicks(d) {

  var k = (d.endAngle - d.startAngle) / d.value;

  return d3.range(0, d.value, 1000).map(function(v, i) {

    return {

      angle: v * k + d.startAngle,

      label: i % 5 ? null : v / 1000 + "k"

    };

  });

}

/** Returns an event handler for fading a given chord group. */

function fade(opacity) {

  return function(g, i) {

    svg.selectAll("g.chord path")

        .filter(function(d) {

          return d.source.index != i && d.target.index != i;

        })

      .transition()

        .style("opacity", opacity);

  };

}