D3 Examples - Sankey diagram of greenhouse gas production in 2005 v5

Sankey diagram of greenhouse gas production in 2005 v5

This is an example of a Sankey diagram made using d3.js and the sankey plugin.

A description of how it was put together and techniques for implimenting Sankey diagrams in general with d3.js can be found with the full text in the book D3 Tips and Tricks (for free) from Leanpub.

The data is sourced from the World Resources Institute (http://www.wri.org/chart/world-greenhouse-gas-emissions-2005).

Open in full window for full effect.

This is one of the code samples for the update to the book D3 Tips and Tricks to version 5 of d3.js.

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<!DOCTYPE html>
<meta charset="utf-8">
<title>SANKEY Experiment</title>
<style>
​
.node rect {
  cursor: move;
  fill-opacity: .9;
  shape-rendering: crispEdges;
}
​
.node text {
  pointer-events: none;
  text-shadow: 0 1px 0 #fff;
}
​
.link {
  fill: none;
  stroke: #000;
  stroke-opacity: .2;
}
​
.link:hover {
  stroke-opacity: .5;
}
​
</style>
<body>
​
<p id="chart">
​
<script src="https://d3js.org/d3.v5.min.js"></script>
<script src="sankey.js"></script>
<script>
  
var units = "Widgets";
​
var margin = {top: 10, right: 10, bottom: 10, left: 10},
    width = 1200 - margin.left - margin.right,
    height = 740 - margin.top - margin.bottom;
​
// format variables
var formatNumber = d3.format(",.0f"),    // zero decimal places
    format = function(d) { return formatNumber(d) + " " + units; },
    color = d3.scaleOrdinal(d3.schemeCategory10);
  
// append the svg canvas to the page
var svg = d3.select("#chart").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 + ")");
  
// Set the sankey diagram properties
var sankey = d3.sankey()
    .nodeWidth(36)
    .nodePadding(10)
    .size([width, height]);
  
var path = sankey.link();
​
// load the data
d3.json("sankeygreenhouse.json").then(function(graph) {
​
    var nodeMap = {};
    graph.nodes.forEach(function(x) { nodeMap[x.name] = x; });
    graph.links = graph.links.map(function(x) {
      return {
        source: nodeMap[x.source],
        target: nodeMap[x.target],
        value: x.value
      };
    });
​
  sankey
      .nodes(graph.nodes)
      .links(graph.links)
      .layout(32);
​
// add in the links
  var link = svg.append("g").selectAll(".link")
      .data(graph.links)
    .enter().append("path")
      .attr("class", "link")
      .attr("d", path)
      .style("stroke-width", function(d) { return Math.max(1, d.dy); })
      .sort(function(a, b) { return b.dy - a.dy; });
​
// add the link titles
  link.append("title")
        .text(function(d) {
            return d.source.name + " → " + 
                d.target.name + "\n" + format(d.value); });
​
// add in the nodes
  var node = svg.append("g").selectAll(".node")
      .data(graph.nodes)
    .enter().append("g")
      .attr("class", "node")
      .attr("transform", function(d) { 
          return "translate(" + d.x + "," + d.y + ")"; })
    .call(d3.drag()
        .subject(function(d) {
          return d;
        })
        .on("start", function() {
          this.parentNode.appendChild(this);
        })
        .on("drag", dragmove));
​
// add the rectangles for the nodes
  node.append("rect")
      .attr("height", function(d) { return d.dy; })
      .attr("width", sankey.nodeWidth())
      .style("fill", function(d) { 
          return d.color = color(d.name.replace(/ .*/, "")); })
      .style("stroke", function(d) { 
          return d3.rgb(d.color).darker(2); })
    .append("title")
      .text(function(d) { 
          return d.name + "\n" + format(d.value); });
​
// add in the title for the nodes
  node.append("text")
      .attr("x", -6)
      .attr("y", function(d) { return d.dy / 2; })
      .attr("dy", ".35em")
      .attr("text-anchor", "end")
      .attr("transform", null)
      .text(function(d) { return d.name; })
    .filter(function(d) { return d.x < width / 2; })
      .attr("x", 6 + sankey.nodeWidth())
      .attr("text-anchor", "start");
​
// the function for moving the nodes
  function dragmove(d) {
    d3.select(this).attr("transform", 
        "translate(" + d.x + "," + (
                d.y = Math.max(0, Math.min(height - d.dy, d3.event.y))
            ) + ")");
    sankey.relayout();
    link.attr("d", path);
  }
});
​
</script>
​
</body>
</html>
​
    