chart = {
const height = width;
const color = d3.scaleOrdinal(d3.schemeTableau10);
const context = DOM.context2d(width, height);
const nodes = data.map(Object.create);
const simulation = d3.forceSimulation(nodes)
.alphaTarget(0.3) // stay hot
.velocityDecay(0.1) // low friction
.force("x", d3.forceX().strength(0.01))
.force("y", d3.forceY().strength(0.01))
.force("collide", d3.forceCollide().radius(d => d.r + 1).iterations(3))
.force("charge", d3.forceManyBody().strength((d, i) => i ? 0 : -width * 2 / 3))
.on("tick", ticked);
d3.select(context.canvas)
.on("touchmove", event => event.preventDefault())
.on("pointermove", pointermoved);
invalidation.then(() => simulation.stop());
function pointermoved(event) {
const [x, y] = d3.pointer(event);
nodes[0].fx = x - width / 2;
nodes[0].fy = y - height / 2;
}
function ticked() {
context.clearRect(0, 0, width, height);
context.save();
context.translate(width / 2, height / 2);
for (let i = 1; i < nodes.length; ++i) {
const d = nodes[i];
context.beginPath();
context.moveTo(d.x + d.r, d.y);
context.arc(d.x, d.y, d.r, 0, 2 * Math.PI);
context.fillStyle = color(d.group);
context.fill();
}
context.restore();
}
return context.canvas;
}
data = {
const k = width / 200;
const r = d3.randomUniform(k, k * 4);
const n = 4;
return Array.from({length: 200}, (_, i) => ({r: r(), group: i && (i % n + 1)}));
}
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
