D3 Examples - Voronoi Arc Map

Voronoi Arc Map
Mouseover to see flights originating at the specified airport. The cool thing about this technique is that the interaction requires zero JavaScript — it’s all done in CSS using the :hover state to toggle visibility of an airport’s associated outgoing flight routes.
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<!DOCTYPE html>
<meta charset="utf-8">
<style>
​
.states {
  fill: #ccc;
}
​
.state-borders {
  fill: none;
  stroke: #fff;
  stroke-width: 1.5px;
  stroke-linejoin: round;
  stroke-linecap: round;
}
​
.airport-arcs {
  display: none;
  fill: none;
  stroke: #000;
}
​
.airport-cell {
  fill: none;
  pointer-events: all;
}
​
.airports circle {
  fill: steelblue;
  stroke: #fff;
  pointer-events: none;
}
​
.airport:hover .airport-arcs {
  display: inline;
}
​
/* svg:not(:hover) .airport-cell {
  stroke: #000;
  stroke-opacity: .2;
} */
​
</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/queue.v1.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>
​
var width = 960,
    height = 500;
​
var projection = d3.geo.albers()
    .translate([width / 2, height / 2])
    .scale(1080);
​
var path = d3.geo.path()
    .projection(projection);
​
var voronoi = d3.geom.voronoi()
    .x(function(d) { return d.x; })
    .y(function(d) { return d.y; })
    .clipExtent([[0, 0], [width, height]]);
​
var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);
​
queue()
    .defer(d3.json, "https://gist.githubusercontent.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/us.json")
    .defer(d3.csv, "airports.csv")
    .defer(d3.csv, "flights.csv")
    .await(ready);
​
function ready(error, us, airports, flights) {
  if (error) throw error;
​
  var airportById = d3.map(),
      positions = [];
​
  airports.forEach(function(d) {
    airportById.set(d.iata, d);
    d.outgoing = [];
    d.incoming = [];
  });
​
  flights.forEach(function(flight) {
    var source = airportById.get(flight.origin),
        target = airportById.get(flight.destination),
        link = {source: source, target: target};
    source.outgoing.push(link);
    target.incoming.push(link);
  });
​
  airports = airports.filter(function(d) {
    if (d.count = Math.max(d.incoming.length, d.outgoing.length)) {
      d[0] = +d.longitude;
      d[1] = +d.latitude;
      var position = projection(d);
      d.x = position[0];
      d.y = position[1];
      return true;
    }
  });
​
  voronoi(airports)
      .forEach(function(d) { d.point.cell = d; });
​
  svg.append("path")
      .datum(topojson.feature(us, us.objects.land))
      .attr("class", "states")
      .attr("d", path);
​
  svg.append("path")
      .datum(topojson.mesh(us, us.objects.states, function(a, b) { return a !== b; }))
      .attr("class", "state-borders")
      .attr("d", path);
​
  var airport = svg.append("g")
      .attr("class", "airports")
    .selectAll("g")
      .data(airports.sort(function(a, b) { return b.count - a.count; }))
    .enter().append("g")
      .attr("class", "airport");
​
  airport.append("path")
      .attr("class", "airport-cell")
      .attr("d", function(d) { return d.cell.length ? "M" + d.cell.join("L") + "Z" : null; });
​
  airport.append("g")
      .attr("class", "airport-arcs")
    .selectAll("path")
      .data(function(d) { return d.outgoing; })
    .enter().append("path")
      .attr("d", function(d) { return path({type: "LineString", coordinates: [d.source, d.target]}); });
​
  airport.append("circle")
      .attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; })
      .attr("r", function(d, i) { return Math.sqrt(d.count); });
​
}
​
</script>
​
    