Random Graph Generator

Click anywhere to generate a new random graph.

The nodes are colored by the number of their neighbors.
Nodes with higher number of neighbours are bigger.

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

<body>

var width = 960, height = 500, colors = d3.scale.category10();

var n = 20, // number of nodes
    m = 22, // number of links
    charge = -1000;

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height)
    .on("mousedown", create);

create();

function create () {
  svg.selectAll(".link, .node").remove();
  randomGraph(n, m, charge);
}

function randomGraph (n, m, charge) { //creates a random graph on n nodes and m links
  var nodes = d3.range(n).map(Object),
      list  = randomChoose(unorderedPairs(d3.range(n)), m),
      links = list.map(function (a) { return {source: a[0], target: a[1]} });

var force = d3.layout.force()
      .size([width, height])
      .nodes(nodes)
      .links(links)
      .charge(charge)
      .on("tick", tick)
      .start();

var svgLinks = svg.selectAll(".link").data(links)
    .enter().append("line")
      .attr("class", "link");

var svgNodes = svg.selectAll(".node").data(nodes)
    .enter().append("circle")
      .attr("class", "node")
      .attr("r", 3)
      .style("fill", "white");

svgNodes.transition().duration(800)
      .attr("r", function (d) { return 3 + 3 * d.weight })
      .style("fill", function (d) { return colors(d.weight) });

svgLinks.transition().duration(800)
      .style("stroke-width", 3);

function tick () {
    svgNodes
        .attr("cx", function(d) { return d.x })
        .attr("cy", function(d) { return d.y });

svgLinks
        .attr("x1", function(d) { return d.source.x })
        .attr("y1", function(d) { return d.source.y })
        .attr("x2", function(d) { return d.target.x })
        .attr("y2", function(d) { return d.target.y });
  }
}

function randomChoose (s, k) { // returns a random k element subset of s
  var a = [], i = -1, j;
  while (++i < k) {
    j = Math.floor(Math.random() * s.length);
    a.push(s.splice(j, 1)[0]);
  };
  return a;
}

function unorderedPairs (s) { // returns the list of all unordered pairs from s
  var i = -1, a = [], j;
  while (++i < s.length) {
    j = i;
    while (++j < s.length) a.push([s[i],s[j]])
  };
  return a;
}

</script>

Modified http://d3js.org/d3.v3.min.js to a secure url

https://d3js.org/d3.v3.min.js