D3.js Chord Diagram - Make chords touch the pulled apart arc

Question

D3.js Chord Diagram - Make chords touch the pulled apart arc

648 Views Asked by Popo.J At 10 April 2025 at 20:24

D3 and Javascript newbie here. I am making a chord diagram with one arc that is pulled apart from the center. I have managed to move the arc into my desire position but I wonder how do I make the group of chord touching the arc again and not messing up the position of other groups of chords?

Here is an image to explain my desired result.

I am currently using an if statement to select the angle where arc C is staying and translate its position.

.attr("transform", function(d) {
            if (d.startAngle > Math.PI*1/2 && d.startAngle < Math.PI*5/6) {
                            return "transform", "translate(" + pullOutSize + "," + pullOutSize + ")"}
        ;})

I am able to translate the position of the chords by using the translate as well.

.attr("transform", "translate(" + 50 + "," + 50 + ")")
.attr("d", path);

However, when I applied the same if statement to it the translate stop working. It seems like the if statement does not met the condition. I wonder what will be the right statement to put into the if statement to help me select the section of chords that I am trying to move.

.attr("transform", function(d) {
            if (d.startAngle > Math.PI*1/2 && d.startAngle < Math.PI*5/6) {
                            return "transform", "translate(" + pullOutSize + "," + pullOutSize + ")"}
        ;})

Thanks!

Original Q&A

There are 1 best solutions below

**Umesh Maharshi** · Answer 1

According to the documentation, you can pass the radius as a parameter when creating the chord/ribbon.

Documentation for ribbon

// from documentation
   var ribbon = d3.ribbon();
     ribbon({
            source: {startAngle: 0.7524114, endAngle: 1.1212972, radius: 240},
            target: {startAngle: 1.8617078, endAngle: 1.9842927, radius: 240}
     });

<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  font: 20px sans-serif;
}

.group-tick line {
  stroke: #000;
}

.ribbons {
  fill-opacity: 0.67;
}

</style>
<svg width="800" height="800">
<defs>
      <linearGradient id="Gradient1">
        <stop class="stop1" offset="0%"/>
        <stop class="stop2" offset="50%"/>
        <stop class="stop3" offset="100%"/>
      </linearGradient>
      <linearGradient id="Gradient2" x1="0" x2="0" y1="0" y2="1">
        <stop offset="0%" stop-color="red"/>
        <stop offset="50%" stop-color="black" stop-opacity="0"/>
        <stop offset="100%" stop-color="blue"/>
      </linearGradient>
  </defs>
</svg>
<script src="https://d3js.org/d3.v5.min.js"></script>
<script>

var matrixData={
  "Occupants":
  [0, 10,10,10,10,0,0,0,10,10,10,10,10],
  "Flooring":
  [70,0,0,0,0,0,30,0,0,0,0,0,0],
  "Millwork":
  [40, 0,0,0,0,0,60,0,0,0,0,0],
  "Ceilings": 
  [60, 0,0,0,0,0,40,0,0,0,0,0,0],
  "Wet Applied Products":
  [60, 0,0,0,0,0,40,0,0,0,0,0,0],
  "Curtain Wall":
  [0, 0,0,0,0,0,100,0,0,0,0,0,0],
  "Environment":
  [0, 10,10,10,10,0,10,0,10,10,10,0,10],
  "Roofing":
  [0, 0,0,0,0,0,80,0,0,0,0,0],
  "Insulation":
  [50, 0,0,0,0,0,50,0,0,0,0,0,0],
  "MEPFP":
  [40, 0,0,0,0,0,60,0,0,0,0,0,0],
  "Structure": 
  [50, 0,0,0,0,0,50,0,0,0,0,0,0],
  "Furniture":
  [90, 0,0,0,0,0,10,0,0,0,0,0,0]
}


matrix= Object.values(matrixData);
matrixKeys = Object.keys(matrixData);
  
var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height"),
    outerRadius = Math.min(width, height) * 0.5 - 150,
    innerRadius = outerRadius - 30;

 
 
var formatValue = d3.formatPrefix(",.0", 1e3);

var chord = d3.chord()
    .padAngle(0.024)
    .sortSubgroups(d3.descending);

var arc = d3.arc()
    .innerRadius(innerRadius)
    .outerRadius(outerRadius);

var ribbon = d3.ribbon();

var color = d3.scaleOrdinal()
    .domain(d3.range(4))
    .range(["#6FCDE3", 
            "#D7DAE5", 
            "#D7DAE5", 
            "#D7DAE5", 
            "#D7DAE5", 
            "#D7DAE5", 
            "#E5E52B",
            "#D7DAE5",
            "#D7DAE5", 
            "#D7DAE5", 
            "#D7DAE5", 
            "#D7DAE5"
           ]);

var g = svg.append("g")
    .attr("transform", "translate(" + width / 2 + "," + height / 2 + ") rotate(75)")
    .datum(chord(matrix));

var group = g.append("g")
    .attr("class", "groups")
  .selectAll("g")
  .data(function(chords) { return chords.groups; })
  .enter().append("g");

group.append("path")
    .style("fill", function(d) { return color(d.index); })
    .style("stroke", function(d) { return d3.rgb(color(d.index)).darker(); })
    .attr("d", function(d,i) { 
  var radius = 0;
  if(d.index%2 != 0) radius = 50;
  return arc.innerRadius(innerRadius + radius)
    .outerRadius(outerRadius + radius)(d);}).on("mouseover", function(d,i) {
  fade(.1,d);
 })
    .on("mouseout", function(d,i) {
  fade(1,d);
 });

var groupTick = group.selectAll(".group-tick")
  .data(function(d) { return groupTicks(d, 1e3); })
  .enter().append("g")
    .attr("class", "group-tick")
    .attr("transform", function(d) { 
   var radius = 0;
   if(d.index%2 != 0) radius = 50;
      return "rotate(" + (d.angle * 180 / Math.PI - 75) + 
        ") translate(" + (outerRadius + radius) + ",2)"; 
    });

groupTick.append("line")
    .attr("x2", 6);

groupTick
  .filter(function(d) { return d.value % 5e3 === 0; })
  .append("text")
    .attr("x", 8)
    .attr("dy", ".35em")
    .attr("transform", function(d) { return d.angle > Math.PI/2 && d.angle < Math.PI*3/2 ? "rotate(180) translate(-16)" : null; })
    .style("text-anchor", function(d) { return d.angle > Math.PI/2 && d.angle < Math.PI*3/2? "end" : null; })
    .text(function(d) { 
  return matrixKeys[d.index]; 
});

g.append("g")
    .attr("class", "ribbons")
  .selectAll("path")
  .data(function(chords) { 
 return chords; })
  .enter().append("path")
    .attr("d", function(d) {
  if(d.source.index%2 == 0) d.source.radius = innerRadius;
  else d.source.radius = innerRadius + 50;
  if(d.target.index%2 == 0) d.target.radius = innerRadius;
  else d.target.radius = innerRadius + 50;
  return ribbon(d);
 })
 .attr("class", function(d,i) { return matrixKeys[d.index]})
    .style("fill", function(d) { return color(d.target.index); })
    .style("stroke", function(d) { return d3.rgb(color(d.target.index)).darker(); });

  
 
// Returns an array of tick angles and values for a given group and step.
function groupTicks(d, step) {
  var k = (d.endAngle - d.startAngle) / d.value;
  return d3.range(0, d.value, step).map(function(value) {
    return {
      index:d.index,
      value: value, 
      angle: value * k + d.startAngle
    };
  });
}

function fade(opacity, d2) {
   var hightLight = g.selectAll(".ribbons path").filter(function(d) { 
    return d.source.index != d2.index && d.target.index != d2.index;
   });
   hightLight.transition()
                    .style("opacity", opacity);
        }

</script>

D3.js Chord Diagram - Make chords touch the pulled apart arc

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