D3 Examples - Greenhouse Gases Sankey Particles

Greenhouse Gases Sankey Particles

a Sankey Particles visualization of the greenhouse gas production data from @d3noob

the #nodejs script createGraph.js modifies sankeygreenhouse.json from the Sankey diagram of greenhouse gas production in 2005 bl.ock to use the node indices as values for the link source and target properties (rather than using the node names). the result is graph.json, a graph object in the format expected by our Sankey Particles vis

to run createGraph.js yourself, cd into the directory that contains this bl.ock and run these commands from the terminal:

npm i node createGraph.js

this will install the dependencies from package.json and then run createGraph.js

further research

in this example some link paths occlude other link paths. Node labels that are drawn over links present further occlusion issues. I'd like to see a method to resolve this occlusion, or element-overlap. using a scale based on the number of nodes at each depth level of the graph to set the font size could help. for this example, we manually set the font-size to 12px.

using an interaction to only show certain links or certains sets of related links may also reduce path occlusion and improve legibility.

please do share ideas + iterations with me on twitter @micahstubbs

Original README.md:

Using particles to indicate flow between reservoirs in a sankey diagram. This time with particles moving at varying speeds and maintaining the color of the source node. You can drag the reservoirs (the rectangles) to adjust the path of the flows.

Other examples of sankeys with particles:

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​
<!DOCTYPE html>
​
<html lang="en">
<head>
<meta charset="utf-8" />
<title>Sankey Particles</title>
</head>
<body>
<canvas width="1000" height="1000" ></canvas>
<svg width="1000" height="1000" ></svg>
​
<script src="https://d3js.org/d3.v3.min.js" charset="utf-8" type="text/javascript"></script>
<script src="d3.sankey.js" charset="utf-8" type="text/javascript"></script>
<script src="https://npmcdn.com/babel-core@5.8.34/browser.min.js"></script>
<script lang='babel' type='text/babel'>
  /* const canvas = */ d3.select('canvas')
    .style('position', 'absolute');
​
  const margin = { top: 1, right: 1, bottom: 6, left: 1 };
  const width = 960 - margin.left - margin.right;
  const height = 500 - margin.top - margin.bottom;
​
  const formatNumber = d3.format(',.0f');
  const format = d => `${formatNumber(d)}`;
  const color = d3.scale.category20();
​
  const svg = d3.select('svg')
    .style('position', 'absolute')
    .attr('width', width + margin.left + margin.right)
    .attr('height', height + margin.top + margin.bottom)
    .append('g')
      .attr('transform', `translate(${margin.left}, ${margin.top})`);
​
  const sankey = d3.sankey()
    .nodeWidth(15)
    .nodePadding(10)
    .size([width, height]);
​
  const path = sankey.link();
​
  /* let freqCounter = 1; */
​
​
  d3.json('graph.json', graph => {
    sankey
      .nodes(graph.nodes)
      .links(graph.links)
      .layout(32);
​
    const link = svg.append('g').selectAll('.link')
      .data(graph.links)
      .enter().append('path')
        .attr('class', 'link')
        .attr('d', path)
        .style('stroke-width', d => Math.max(1, d.dy))
        .style({
          fill: 'none',
          stroke: '#000',
          'stroke-opacity': 0.15
        })
        .sort((a, b) => b.dy - a.dy)
​
    link
      .on('mouseover', function () {
        d3.select(this)
          .style('stroke-opacity', 0.25);
      })
      .on('mouseout', function () {
        d3.select(this)
          .style('stroke-opacity', 0.15);
      });
​
    link.append('title')
      .text(d => `${d.source.name} → ${d.target.name}\n${format(d.value)}`)
​
    const node = svg.append('g').selectAll('.node')
      .data(graph.nodes)
      .enter().append('g')
        .attr('class', 'node')
        .attr('transform', d => `translate(${d.x}, ${d.y})`)
        .call(d3.behavior.drag()
        .origin(d => d)
        .on('dragstart', function () { this.parentNode.appendChild(this); })
        .on('drag', dragmove));
​
    node.append('rect')
      .attr('height', d => d.dy)
      .attr('width', sankey.nodeWidth())
      .style('fill', d => {
        d.color = color(d.name.replace(/ .*/, ''));
        return d.color;
      })
      .style({
        stroke: 'none',
        cursor: 'move',
        'fill-opacity': 0.9,
        'shape-rendering': 'crispEdges'
      })
      .append('title')
        .text(d => `${d.name}\n${format(d.value)}`);
​
    node.append('text')
      .attr('x', -6)
      .attr('y', d => d.dy / 2)
      .attr('dy', '.35em')
      .attr('text-anchor', 'end')
      .attr('transform', null)
      .style({
        'pointer-events': 'none',
        'text-shadow': '0 1px 0 #fff',
        'font-size': '12px'
​
      })
      .text(d => d.name)
      .filter(d => d.x < width / 2)
        .attr('x', 6 + sankey.nodeWidth())
        .attr('text-anchor', 'start')
        .style('font-size', '12px');
​
    function dragmove(d) {
      d3.select(this)
        .attr('transform', `translate(${d.x}, ${(d.y = Math.max(0, Math.min(height - d.dy, d3.event.y)))})`);
      sankey.relayout();
      link.attr('d', path);
    }
​
    const linkExtent = d3.extent(graph.links, d => d.value);
​
    const frequencyScale = d3.scale.linear()
      .domain(linkExtent)
      .range([0.05, 1]);
​
    /* const particleSize = */ d3.scale.linear()
      .domain(linkExtent)
      .range([1, 5]);
​
    graph.links.forEach(currentLink => {
      currentLink.freq = frequencyScale(currentLink.value);
      currentLink.particleSize = 2;
      currentLink.particleColor = d3.scale.linear().domain([0, 1])
      .range([currentLink.source.color, currentLink.target.color]);
    });
​
    /* const t = */ d3.timer(tick, 1000);
    let particles = [];
​
    function tick(elapsed /* , time */) {
      particles = particles.filter(d => d.current < d.path.getTotalLength());
​
      d3.selectAll('path.link')
      .each(
        function (d) {
  //        if (d.freq < 1) {
          for (let x = 0; x < 2; x++) {
            const offset = (Math.random() - 0.5) * (d.dy - 4);
            if (Math.random() < d.freq) {
              const length = this.getTotalLength();
              particles.push({
                link: d,
                time: elapsed,
                offset,
                path: this,
                length,
                animateTime: length,
                speed: 0.5 + (Math.random())
              });
            }
          }
  //        }
  /*        else {
            for (let x = 0; x<d.freq; x++) {
              let offset = (Math.random() - .5) * d.dy;
              particles.push({link: d, time: elapsed, offset: offset, path: this})
            }
          } */
        });
​
      particleEdgeCanvasPath(elapsed);
    }
​
    function particleEdgeCanvasPath(elapsed) {
      const context = d3.select('canvas').node().getContext('2d');
​
      context.clearRect(0, 0, 1000, 1000);
​
      context.fillStyle = 'gray';
      context.lineWidth = '1px';
      for (const x in particles) {
        if ({}.hasOwnProperty.call(particles, x)) {
          const currentTime = elapsed - particles[x].time;
  //        let currentPercent = currentTime / 1000 * particles[x].path.getTotalLength();
          particles[x].current = currentTime * 0.15 * particles[x].speed;
          const currentPos = particles[x].path.getPointAtLength(particles[x].current);
          context.beginPath();
          context.fillStyle = particles[x].link.particleColor(0);
          context.arc(
            currentPos.x,
            currentPos.y + particles[x].offset,
            particles[x].link.particleSize,
            0,
            2 * Math.PI
          );
          context.fill();
        }
      }
    }
  });
</script>
</body>
</html>
    