Sparse Matrix Force Graph by trinary

This is a fork!

This is a small modification to this gist by syntagmatic. I changed how the path colors are calculated in order to batch similar distances together. I also messed with the color scale and interpolation, and changed the distance calculation from the original. Original Readme follows:

The lock1074 graph from the The University of Florida Sparse Matrix Collection.

1,040 nodes with 25,276 edges. Self-edges were removed from the links array. Links are colored by the distance between nodes.

index.html

<!DOCTYPE html>
<meta charset="utf-8">
<style>
</style>
<canvas></canvas>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>
var width = 960,
    height = 600;

var linkColor = d3.scaleThreshold()
  .domain(d3.range(0,200, 20))
  .range(d3.range(0.5,1.0,0.05));

var canvas = d3.select("canvas")
    .attr("width", width)
    .attr("height", height);

var context = canvas.node().getContext("2d");

var simulation = d3.forceSimulation()
    .force("link", d3.forceLink().id(function(d) { return d.id; }).distance(22).strength(0.2))
    .force("charge", d3.forceManyBody().strength(-6).distanceMax(380))
    .force("center", d3.forceCenter(width / 2, height / 2));

var graph = {};

d3.text("lock1074.mtx", function(error, raw) {
  if (error) throw error;

  var node_set = d3.set();

  var pairs = raw.split("\n")
    .slice(14)
    .map(function(d) { return d.split(" "); });

  pairs.forEach(function(d) {
    node_set.add(d[0]);
    node_set.add(d[1]);
  });

  graph.nodes = node_set.values().map(function(d) {
      return {
        id: d
      };
    });

  graph.links = pairs.map(function(d) {
      return {
        source: d[0],
        target: d[1]
      }
    })
    .filter(function(d) {
      return d.source !== d.target;
    });

  simulation
      .nodes(graph.nodes)

  simulation.force("link")
      .links(graph.links);

  d3.range(10).forEach(simulation.tick);

  simulation
      .on("tick", ticked);

  canvas.call(d3.drag()
          .container(canvas.node())
          .subject(dragsubject)
          .on("start", dragstarted)
          .on("drag", dragged)
          .on("end", dragended));

  function ticked() {
    context.clearRect(0, 0, width, height);

    context.globalAlpha = 0.2;
    drawLinks(graph.links);

    context.globalAlpha = 1;
    context.fillStyle = d3.interpolateViridis(0.15);
    graph.nodes.forEach(drawNode);
  }

  function dragsubject() {
    return simulation.find(d3.event.x, d3.event.y);
  }
});

function dragstarted() {
  if (!d3.event.active) simulation.alphaTarget(0.3).restart();
  d3.event.subject.fx = d3.event.subject.x;
  d3.event.subject.fy = d3.event.subject.y;
}

function dragged() {
  d3.event.subject.fx = d3.event.x;
  d3.event.subject.fy = d3.event.y;
}

function dragended() {
  if (!d3.event.active) simulation.alphaTarget(0);
  d3.event.subject.fx = null;
  d3.event.subject.fy = null;
}

function drawLinks(links) {
  var linkBatches = d3.map();
  linkColor.range().map(function(d, i) { linkBatches.set(d, []);});
  links.forEach(function(d) {
    var distance = Math.sqrt( Math.pow(d.source.x - d.target.x, 2) + Math.pow(d.source.y - d.target.y, 2));
    var batch = linkColor(distance);
    var currentList = linkBatches.get(batch);
    currentList.push([[d.source.x, d.source.y],[d.target.x, d.target.y]]);
    linkBatches.set(batch, currentList);
  });

  linkBatches.each(function(v, k) {
    context.beginPath();
    v.forEach(function(points) {
      context.moveTo(points[0][0], points[0][1]);
      context.lineTo(points[1][0], points[1][1]);
    });
    context.strokeStyle = d3.interpolatePlasma(parseFloat(k));
    context.stroke();
  });
}

function drawNode(d) {
//  context.fillStyle = d3.interpolateMagma(Math.sqrt(d.vx*d.vx + d.vy*d.vy));
  context.fillRect(d.x-0.75, d.y-0.75, 1.5, 1.5);
}

</script>