分层边缘捆绑 - 径向树状图和颜色中自动生成的弧

Question

早在2012年10月，就如何在径向树状图中生成弧来表示群体提出了这个问题（d3.js - how to automatically calculate arc lengths in radial dendrogram）。用户“wceo”发布了一个非常好用的优雅解决方案。

但是，是否可以单独更改每个弧的颜色，而不是将它们作为相同的颜色？甚至尝试......

var color = d3.scale.category20();

......和......

var groupData = svg.selectAll("g.group")
.data(nodes.filter(function(d) { return (d.key=='400' || d.key == '500' || d.key == '600' || d.key == 'Current_Missions' || d.key == 'Future_Missions') && d.children; }))
.enter().append("group")
.attr("class", "group")
.attr("fill", function(d) { return color(d.group); });

...只返回五个弧中的每一个作为相同的颜色。

（我为没有回复原来的主题而道歉。我显然没有这样做的50个声誉。）

（编辑包含整个示例代码）

var w = 1800,
    h = 1600,
    rx = w / 2,
    ry = h / 2,
    m0,
    rotate = 0
    pi = Math.PI;

var splines = [];

var cluster = d3.layout.cluster()
    .size([360, ry - 400])
    .sort(function(a, b) { return d3.ascending(a.key, b.key); });

var bundle = d3.layout.bundle();

var line = d3.svg.line.radial()
    .interpolate("bundle")
    .tension(.85)
    .radius(function(d) { return d.y; })
    .angle(function(d) { return d.x / 180 * Math.PI; });

// Chrome 15 bug: <http://code.google.com/p/chromium/issues/detail?id=98951>
var div = d3.select("#bundle")
    .style("top", "50px")
    .style("left", "50px")    
    .style("width", w + "px")
    .style("height", w + "px")
    .style("position", "absolute");

var svg = div.append("svg:svg")
    .attr("width", w)
    .attr("height", w)
  .append("svg:g")
    .attr("transform", "translate(" + rx + "," + ry + ")");

var color = d3.scale.ordinal();

svg.append("svg:path")
    .attr("class", "arc")
    .attr("d", d3.svg.arc().outerRadius(ry - 180).innerRadius(0).startAngle(0).endAngle(2 * Math.PI))
    .on("mousedown", mousedown);

d3.json("missions.json", function(classes) {
  var nodes = cluster.nodes(packages.root(classes)),
      links = packages.imports(nodes),
      splines = bundle(links);

  var path = svg.selectAll("path.link")
      .data(links)
    .enter().append("svg:path")
      .attr("class", function(d) { return "link source-" + d.source.key + " target-" + d.target.key; })
      .attr("d", function(d, i) { return line(splines[i]); });

  var groupData = svg.selectAll("g.group")
    .data(nodes.filter(function(d) { return (d.key == '400' || d.key == '500' || d.key == '600' || d.key == 'Current_Missions' || d.key == 'Future_Missions') && d.children; }))
  .enter().append("group")
    .attr("class", "group");

  var groupArc = d3.svg.arc()
  .innerRadius(ry - 430)
  .outerRadius(ry - 400)
  .startAngle(function(d) { return (findStartAngle(d.__data__.children)-2) * pi / 180;})
  .endAngle(function(d) { return (findEndAngle(d.__data__.children)+2) * pi / 180});

  svg.selectAll("g.arc")
  .data(groupData[0])
.enter().append("svg:path")
  .attr("d", groupArc)
  .attr("class", "groupArc")
  .style("fill-opacity", 0.25);

  svg.selectAll("g.node")
      .data(nodes.filter(function(n) { return !n.children; }))
    .enter().append("svg:g")
      .attr("class", "node")
      .attr("id", function(d) { return "node-" + d.key; })
      .attr("transform", function(d) { return "rotate(" + (d.x - 90) + ")translate(" + d.y + ")"; })
    .append("svg:text")
      .attr("dx", function(d) { return d.x < 180 ? 2 : -2; })
      .attr("dy", ".31em")
      .attr("text-anchor", function(d) { return d.x < 180 ? "start" : "end"; })
      .attr("transform", function(d) { return d.x < 180 ? null : "rotate(180)"; })
      .attr("color", function (d) { return (d.color) })
      .text(function(d) { return d.key.replace(/_/g, ' '); })
      .on("mouseover", mouseover)
      .on("mouseout", mouseout);

  d3.select("input[type=range]").on("change", function() {
    line.tension(this.value / 100);
    path.attr("d", function(d, i) { return line(splines[i]); });
  });
});

d3.select(window)
    .on("mousemove", mousemove)
    .on("mouseup", mouseup);

function mouse(e) {
  return [e.pageX - rx, e.pageY - ry];
}

function mousedown() {
  m0 = mouse(d3.event);
  d3.event.preventDefault();
}

function mousemove() {
  if (m0) {
    var m1 = mouse(d3.event),
        dm = Math.atan2(cross(m0, m1), dot(m0, m1)) * 180 / Math.PI;
    div.style("-webkit-transform", "translate3d(0," + (ry - rx) + "px,0)rotate3d(0,0,0," + dm + "deg)translate3d(0," + (rx - ry) + "px,0)");
  }
}

function mouseup() {
  if (m0) {
    var m1 = mouse(d3.event),
        dm = Math.atan2(cross(m0, m1), dot(m0, m1)) * 180 / Math.PI;

    rotate += dm;
    if (rotate > 360) rotate -= 360;
    else if (rotate < 0) rotate += 360;
    m0 = null;

    div.style("-webkit-transform", "rotate3d(0,0,0,0deg)");

    svg.attr("transform", "translate(" + rx + "," + ry + ")rotate(" + rotate + ")")
      .selectAll("g.node text")
        .attr("dx", function(d) { return (d.x + rotate) % 360 < 180 ? 2 : -2; })
        .attr("text-anchor", function(d) { return (d.x + rotate) % 360 < 180 ? "start" : "end"; })
        .attr("transform", function(d) { return (d.x + rotate) % 360 < 180 ? null : "rotate(180)"; });
  }
}

function mouseover(d) {
  svg.selectAll("path.link.target-" + d.key)
      .classed("target", true)
      .each(updateNodes("source", true));

  svg.selectAll("path.link.source-" + d.key)
      .classed("source", true)
      .each(updateNodes("target", true));
}

function mouseout(d) {
  svg.selectAll("path.link.source-" + d.key)
      .classed("source", false)
      .each(updateNodes("target", false));

  svg.selectAll("path.link.target-" + d.key)
      .classed("target", false)
      .each(updateNodes("source", false));
}

function updateNodes(name, value) {
  return function(d) {
    if (value) this.parentNode.appendChild(this);
    svg.select("#node-" + d[name].key).classed(name, value);
  };
}

function cross(a, b) {
  return a[0] * b[1] - a[1] * b[0];
}

function dot(a, b) {
  return a[0] * b[0] + a[1] * b[1];
}

function findStartAngle(children) {
    var min = children[0].x;
    children.forEach(function(d) {
       if (d.x < min)
           min = d.x;
    });
    return min;
}

function findEndAngle(children) {
    var max = children[0].x;
    children.forEach(function(d) {
       if (d.x > max)
           max = d.x;
    });
    return max;
}

(function() {
  packages = {

    // Lazily construct the package hierarchy from class names.
    root: function(classes) {
      var map = {};

      function find(name, data) {
        var node = map[name], i;
        if (!node) {
          node = map[name] = data || {name: name, children: []};
          if (name.length) {
            node.parent = find(name.substring(0, i = name.lastIndexOf(".")));
            node.parent.children.push(node);
            node.key = name.substring(i + 1);
          }
        }
        return node;
      }

      classes.forEach(function(d) {
        find(d.name, d);
      });

      return map[""];
    },

    // Return a list of imports for the given array of nodes.
    imports: function(nodes) {
      var map = {},
          imports = [];

      // Compute a map from name to node.
      nodes.forEach(function(d) {
        map[d.name] = d;
      });

      // For each import, construct a link from the source to target node.
      nodes.forEach(function(d) {
        if (d.imports) d.imports.forEach(function(i) {
          imports.push({source: map[d.name], target: map[i]});
        });
      });

      return imports;
    }

  };
})();