1 // Ratio of Obese (BMI >= 30) in U.S. Adults, CDC 2008

     2 var data = [

     3   , .187, .198, , .133, .175, .151, , .1, .125, .171, , .172, .133, , .108,

     4   .142, .167, .201, .175, .159, .169, .177, .141, .163, .117, .182, .153, .195,

     5   .189, .134, .163, .133, .151, .145, .13, .139, .169, .164, .175, .135, .152,

     6   .169, , .132, .167, .139, .184, .159, .14, .146, .157, , .139, .183, .16, .143

     7 ];

     8 

     9 var color = d3.scale.linear()

    10     .domain([d3.min(data), d3.max(data)])

    11     .range(["#aad", "#556"]); 

    12 

    13 var force = d3.layout.force()

    14     .charge(0)

    15     .gravity(0)

    16     .size([960, 500]);

    17 

    18 var svg = d3.select("#chart").append("svg:svg");

    19 

    20 d3.json("../data/us-state-centroids.json", function(states) {

    21   var project = d3.geo.albersUsa(),

    22       idToNode = {},

    23       links = [],

    24       nodes = states.features.map(function(d) {

    25     var xy = project(d.geometry.coordinates);

    26     return idToNode[d.id] = {

    27       x: xy[0],

    28       y: xy[1],

    29       gravity: {x: xy[0], y: xy[1]},

    30       r: Math.sqrt(data[+d.id] * 2500),

    31       value: data[+d.id]

    32     };

    33   });

    34 

    35   force

    36       .nodes(nodes)

    37       .links(links)

    38       .start()

    39       .on("tick", function(e) {

    40     var k = e.alpha * .5,

    41         kg = k * .1;

    42     nodes.forEach(function(a, i) {

    43       // Apply gravity forces.

    44       a.x += (a.gravity.x - a.x) * kg;

    45       a.y += (a.gravity.y - a.y) * kg;

    46       nodes.slice(i + 1).forEach(function(b) {

    47         // Check for collision

    48         var dx = a.x - b.x,

    49             dy = a.y - b.y,

    50             d = a.r + b.r,

    51             lx = Math.abs(dx),

    52             ly = Math.abs(dy);

    53         if (lx < d && ly < d) {

    54           lx = (lx - d) / lx * k;

    55           ly = (ly - d) / ly * k;

    56           dx *= lx;

    57           dy *= ly;

    58           a.x -= dx;

    59           a.y -= dy;

    60           b.x += dx;

    61           b.y += dy;

    62         }

    63       });

    64     });

    65 

    66     svg.selectAll("rect")

    67         .attr("x", function(d) { return d.x - d.r; })

    68         .attr("y", function(d) { return d.y - d.r; });

    69   });

    70 

    71   svg.selectAll("rect")

    72       .data(nodes)

    73     .enter().append("svg:rect")

    74       .style("fill", function(d) { return color(d.value); })

    75       .attr("x", function(d) { return d.x - d.r; })

    76       .attr("y", function(d) { return d.y - d.r; })

    77       .attr("width", function(d) { return d.r * 2; })

    78       .attr("height", function(d) { return d.r * 2; });

    79 });