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Last active Apr 12, 2019
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Multi-Foci Force Layout
license: gpl-3.0

Click to perturb or drag the nodes!

This example demonstrates the flexibility of D3’s force layout. By using position Verlet integration, it is easy to add custom forces to a layout. In this example, the nodes are clustered around four foci using additional forces: the odd nodes are pushed down, the even nodes are pushed up, and a similar bisecting force is applied laterally. These custom forces are based purely on the index of the node, but they could just as easily be derived from properties of data!

<!DOCTYPE html>
<meta charset="utf-8">
<style>
.node {
stroke-width: 1.5px;
}
</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script>
var width = 960,
height = 500;
var fill = d3.scale.category10();
var nodes = d3.range(100).map(function(i) {
return {index: i};
});
var force = d3.layout.force()
.nodes(nodes)
.size([width, height])
.on("tick", tick)
.start();
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
var node = svg.selectAll(".node")
.data(nodes)
.enter().append("circle")
.attr("class", "node")
.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; })
.attr("r", 8)
.style("fill", function(d, i) { return fill(i & 3); })
.style("stroke", function(d, i) { return d3.rgb(fill(i & 3)).darker(2); })
.call(force.drag)
.on("mousedown", function() { d3.event.stopPropagation(); });
svg.style("opacity", 1e-6)
.transition()
.duration(1000)
.style("opacity", 1);
d3.select("body")
.on("mousedown", mousedown);
function tick(e) {
// Push different nodes in different directions for clustering.
var k = 6 * e.alpha;
nodes.forEach(function(o, i) {
o.y += i & 1 ? k : -k;
o.x += i & 2 ? k : -k;
});
node.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; });
}
function mousedown() {
nodes.forEach(function(o, i) {
o.x += (Math.random() - .5) * 40;
o.y += (Math.random() - .5) * 40;
});
force.resume();
}
</script>
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