Modifying a Force Layout

This example demonstrates how to add and remove nodes and links from a force layout. The graph initially appears with three nodes A, B and C connected in a loop. Three seconds later, node B is removed, along with the links B-A and B-C. At six seconds, node B is reintroduced, restoring the original links B-A and B-C. This example uses the general update pattern for data joins.

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

.link {
  stroke: #000;
  stroke-width: 1.5px;
}

.node {
  fill: #000;
  stroke: #fff;
  stroke-width: 1.5px;
}

.node.a { fill: #1f77b4; }
.node.b { fill: #ff7f0e; }
.node.c { fill: #2ca02c; }

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>

var width = 960,
    height = 500;

var color = d3.scale.category10();

var nodes = [],
    links = [];

var force = d3.layout.force()
    .nodes(nodes)
    .links(links)
    .charge(-400)
    .linkDistance(120)
    .size([width, height])
    .on("tick", tick);

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

var node = svg.selectAll(".node"),
    link = svg.selectAll(".link");

// 1. Add three nodes and three links.
setTimeout(function() {
  var a = {id: "a"}, b = {id: "b"}, c = {id: "c"};
  nodes.push(a, b, c);
  links.push({source: a, target: b}, {source: a, target: c}, {source: b, target: c});
  start();
}, 0);

// 2. Remove node B and associated links.
setTimeout(function() {
  nodes.splice(1, 1); // remove b
  links.shift(); // remove a-b
  links.pop(); // remove b-c
  start();
}, 3000);

// Add node B back.
setTimeout(function() {
  var a = nodes[0], b = {id: "b"}, c = nodes[1];
  nodes.push(b);
  links.push({source: a, target: b}, {source: b, target: c});
  start();
}, 6000);

function start() {
  link = link.data(force.links(), function(d) { return d.source.id + "-" + d.target.id; });
  link.enter().insert("line", ".node").attr("class", "link");
  link.exit().remove();

node = node.data(force.nodes(), function(d) { return d.id;});
  node.enter().append("circle").attr("class", function(d) { return "node " + d.id; }).attr("r", 8);
  node.exit().remove();

force.start();
}

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

link.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; });
}

</script>

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