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"};
force.stop();
nodes.push(a, b, c);
links.push({source: 0, target: 1}, {source: 0, target: 2}, {source: 1, target: 2});
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() {
force.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();
}
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>