Clean arc diagram template for d3.js





This example describes the relationships between all the co-authors of a researcher. Basically, 2 researchers are linked if they've published a paper together.


Arc diagram section

Steps:

  • Data input format is Json. This document explains how to get this format from a classic table.

  • Before building this complicated chart, understand how to draw a basic arc diagram, and how to highlight links on hover.

  • All other customization are basic d3.js concept, like using linear scale for node size or color scale for nodes.
<!DOCTYPE html>
<meta charset="utf-8">

<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>

<!-- Load color palette -->
<script src="https://d3js.org/d3-scale-chromatic.v1.min.js"></script>

<!-- Create a div where the graph will take place -->
<div id="my_dataviz"></div>

<script>
// set the dimensions and margins of the graph
var margin = {top: 0, right: 30, bottom: 50, left: 60},
  width = 650 - margin.left - margin.right,
  height = 400 - margin.top - margin.bottom;

// append the svg object to the body of the page
var svg = d3.select("#my_dataviz")
  .append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform",
          "translate(" + margin.left + "," + margin.top + ")");

// Read dummy data
d3.json("https://raw.githubusercontent.com/holtzy/D3-graph-gallery/master/DATA/data_researcherNetwork.json", function( data) {

  // List of node names
  var allNodes = data.nodes.map(function(d){return d.name})

  // List of groups
  var allGroups = data.nodes.map(function(d){return d.grp})
  allGroups = [...new Set(allGroups)]

  // A color scale for groups:
  var color = d3.scaleOrdinal()
    .domain(allGroups)
    .range(d3.schemeSet3);

  // A linear scale for node size
  var size = d3.scaleLinear()
    .domain([1,10])
    .range([2,10]);

  // A linear scale to position the nodes on the X axis
  var x = d3.scalePoint()
    .range([0, width])
    .domain(allNodes)

  // In my input data, links are provided between nodes -id-, NOT between node names.
  // So I have to do a link between this id and the name
  var idToNode = {};
  data.nodes.forEach(function (n) {
    idToNode[n.id] = n;
  });

  // Add the links
  var links = svg
    .selectAll('mylinks')
    .data(data.links)
    .enter()
    .append('path')
    .attr('d', function (d) {
      start = x(idToNode[d.source].name)    // X position of start node on the X axis
      end = x(idToNode[d.target].name)      // X position of end node
      return ['M', start, height-30,    // the arc starts at the coordinate x=start, y=height-30 (where the starting node is)
        'A',                            // This means we're gonna build an elliptical arc
        (start - end)/2, ',',    // Next 2 lines are the coordinates of the inflexion point. Height of this point is proportional with start - end distance
        (start - end)/2, 0, 0, ',',
        start < end ? 1 : 0, end, ',', height-30] // We always want the arc on top. So if end is before start, putting 0 here turn the arc upside down.
        .join(' ');
    })
    .style("fill", "none")
    .attr("stroke", "grey")
    .style("stroke-width", 1)

  // Add the circle for the nodes
  var nodes = svg
    .selectAll("mynodes")
    .data(data.nodes.sort(function(a,b) { return +b.n - +a.n }))
    .enter()
    .append("circle")
      .attr("cx", function(d){ return(x(d.name))})
      .attr("cy", height-30)
      .attr("r", function(d){ return(size(d.n))})
      .style("fill", function(d){ return color(d.grp)})
      .attr("stroke", "white")

  // And give them a label
  var labels = svg
    .selectAll("mylabels")
    .data(data.nodes)
    .enter()
    .append("text")
      .attr("x", 0)
      .attr("y", 0)
      .text(function(d){ return(d.name)} )
      .style("text-anchor", "end")
      .attr("transform", function(d){ return( "translate(" + (x(d.name)) + "," + (height-15) + ")rotate(-45)")})
      .style("font-size", 6)

  // Add the highlighting functionnality
  nodes
    .on('mouseover', function (d) {
      // Highlight the nodes: every node is green except of him
      nodes
        .style('opacity', .2)
      d3.select(this)
        .style('opacity', 1)
      // Highlight the connections
      links
        .style('stroke', function (link_d) { return link_d.source === d.id || link_d.target === d.id ? color(d.grp) : '#b8b8b8';})
        .style('stroke-opacity', function (link_d) { return link_d.source === d.id || link_d.target === d.id ? 1 : .2;})
        .style('stroke-width', function (link_d) { return link_d.source === d.id || link_d.target === d.id ? 4 : 1;})
      labels
        .style("font-size", function(label_d){ return label_d.name === d.name ? 16 : 2 } )
        .attr("y", function(label_d){ return label_d.name === d.name ? 10 : 0 } )

    })
    .on('mouseout', function (d) {
      nodes.style('opacity', 1)
      links
        .style('stroke', 'grey')
        .style('stroke-opacity', .8)
        .style('stroke-width', '1')
      labels
        .style("font-size", 6 )

    })
})

</script>

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