Neighboring Congressional Districts by mbostock

index.html

<!DOCTYPE html>
<meta charset="utf-8">
<style>

path {
  stroke-linejoin: round;
  stroke-linecap: round;
}

.land {
  fill: #bbb;
}

.land :hover {
  fill: red;
}

.land .neighbor {
  fill: orange;
}

.border {
  pointer-events: none;
  fill: none;
  stroke: #fff;
}

.border--district {
  stroke-width: .5px;
}

.border--state {
  stroke-width: 1.5px;
}

</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 = 600;

var projection = d3.geo.albersUsa()
    .scale(1280)
    .translate([width / 2, height / 2]);

var path = d3.geo.path()
    .projection(projection);

var svg = d3.select("body").append("svg")
    .attr("width", width)
    .attr("height", height);

queue()
    .defer(d3.json, "/mbostock/raw/4090846/us.json")
    .defer(d3.json, "/mbostock/raw/4090846/us-congress-113.json")
    .await(ready);

function ready(error, us, congress) {
  if (error) throw error;

  var districts = congress.objects.districts,
      neighbors = topojson.neighbors(districts.geometries);

  svg.append("defs").append("path")
      .attr("id", "land")
      .datum(topojson.feature(us, us.objects.land))
      .attr("d", path);

  svg.append("clipPath")
      .attr("id", "clip-land")
    .append("use")
      .attr("xlink:href", "#land");

  var district = svg.append("g")
      .attr("class", "land")
      .attr("clip-path", "url(#clip-land)")
    .selectAll("path")
      .data(topojson.feature(congress, districts).features)
    .enter().append("path")
      .attr("d", path);

  district.append("title")
      .text(function(d) { return d.id; });

  district
      .each(function(d, i) { d.neighbors = d3.selectAll(neighbors[i].map(function(j) { return district[0][j]; })); })
      .on("mouseover", function(d) { d.neighbors.classed("neighbor", true); })
      .on("mouseout", function(d) { d.neighbors.classed("neighbor", false); });

  svg.append("path")
      .attr("class", "border border--district")
      .datum(topojson.mesh(congress, congress.objects.districts, function(a, b) { return a !== b && (a.id / 1000 | 0) === (b.id / 1000 | 0); }))
      .attr("d", path);

  svg.append("path")
      .attr("class", "border border--state")
      .datum(topojson.mesh(us, us.objects.states, function(a, b) { return a !== b; }))
      .attr("d", path);
}

d3.select(self.frameElement).style("height", height + "px");

</script>