d3/examples/cartogram/dorling.js

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JavaScript

// Ratio of Obese (BMI >= 30) in U.S. Adults, CDC 2008
var data = [
, .187, .198, , .133, .175, .151, , .1, .125, .171, , .172, .133, , .108,
.142, .167, .201, .175, .159, .169, .177, .141, .163, .117, .182, .153, .195,
.189, .134, .163, .133, .151, .145, .13, .139, .169, .164, .175, .135, .152,
.169, , .132, .167, .139, .184, .159, .14, .146, .157, , .139, .183, .16, .143
];
var color = d3.scale.linear()
.domain([d3.min(data), d3.max(data)])
.range(["#aad", "#556"]);
var force = d3.layout.force()
.charge(0)
.gravity(0)
.size([960, 500]);
var svg = d3.select("#chart").append("svg")
.attr("width", 960 + 100)
.attr("height", 500 + 100)
.append("g")
.attr("transform", "translate(50,50)");
d3.json("../data/us-state-centroids.json", function(states) {
var project = d3.geo.albersUsa(),
idToNode = {},
links = [],
nodes = states.features.map(function(d) {
var xy = project(d.geometry.coordinates);
return idToNode[d.id] = {
x: xy[0],
y: xy[1],
gravity: {x: xy[0], y: xy[1]},
r: Math.sqrt(data[+d.id] * 5000),
value: data[+d.id]
};
});
force
.nodes(nodes)
.links(links)
.start()
.on("tick", function(e) {
var k = e.alpha,
kg = k * .02;
nodes.forEach(function(a, i) {
// Apply gravity forces.
a.x += (a.gravity.x - a.x) * kg;
a.y += (a.gravity.y - a.y) * kg;
nodes.slice(i + 1).forEach(function(b) {
// Check for collisions.
var dx = a.x - b.x,
dy = a.y - b.y,
l = Math.sqrt(dx * dx + dy * dy),
d = a.r + b.r;
if (l < d) {
l = (l - d) / l * k;
dx *= l;
dy *= l;
a.x -= dx;
a.y -= dy;
b.x += dx;
b.y += dy;
}
});
});
svg.selectAll("circle")
.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; });
});
svg.selectAll("circle")
.data(nodes)
.enter().append("circle")
.style("fill", function(d) { return color(d.value); })
.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; })
.attr("r", function(d, i) { return d.r; });
});