County Bubbles by mbostock

index.html

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

.land {
  fill: #ddd;
}

.border {
  fill: none;
  stroke: #fff;
  stroke-linejoin: round;
  stroke-linecap: round;
}

.bubble {
  fill: brown;
  fill-opacity: .5;
  stroke: #fff;
  stroke-width: .5px;
}

.bubble :hover {
  stroke: #000;
}

.legend circle {
  fill: none;
  stroke: #ccc;
}

.legend text {
  fill: #777;
  font: 10px sans-serif;
  text-anchor: middle;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>

var width = 960,
    height = 600;

var formatNumber = d3.format(",.0f");

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

var radius = d3.scale.sqrt()
    .domain([0, 1e6])
    .range([0, 15]);

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

var legend = svg.append("g")
    .attr("class", "legend")
    .attr("transform", "translate(" + (width - 50) + "," + (height - 20) + ")")
  .selectAll("g")
    .data([1e6, 5e6, 1e7])
  .enter().append("g");

legend.append("circle")
    .attr("cy", function(d) { return -radius(d); })
    .attr("r", radius);

legend.append("text")
    .attr("y", function(d) { return -2 * radius(d); })
    .attr("dy", "1.3em")
    .text(d3.format(".1s"));

d3.json("us.json", function(error, us) {
  if (error) throw error;

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

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

  svg.append("g")
      .attr("class", "bubble")
    .selectAll("circle")
      .data(topojson.feature(us, us.objects.counties).features
        .sort(function(a, b) { return b.properties.population - a.properties.population; }))
    .enter().append("circle")
      .attr("transform", function(d) { return "translate(" + path.centroid(d) + ")"; })
      .attr("r", function(d) { return radius(d.properties.population); })
    .append("title")
      .text(function(d) {
        return d.properties.name
            + "\nPopulation " + formatNumber(d.properties.population);
      });
});

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

</script>

Makefile

all: us.json

clean:
	rm -rf -- us.json build

.PHONY: all clean

build/gz_2010_us_050_00_20m.shp: build/gz_2010_us_050_00_20m.zip
	unzip -od $(dir $@) $<
	touch $@

build/gz_2010_us_050_00_20m.zip:
	mkdir -p $(dir $@)
	curl -o $@ http://www2.census.gov/geo/tiger/GENZ2010/gz_2010_us_050_00_20m.zip

build/counties.json: build/gz_2010_us_050_00_20m.shp ACS_12_5YR_B01003_with_ann.csv
	node_modules/.bin/topojson \
		-o $@ \
		--id-property='STATE+COUNTY,Id2' \
		--external-properties=ACS_12_5YR_B01003_with_ann.csv \
		--properties='name=Geography,population=+d.properties["Estimate; Total"]' \
		--projection='width = 960, height = 600, d3.geo.albersUsa() \
			.scale(1280) \
			.translate([width / 2, height / 2])' \
		--simplify=.5 \
		-- counties=$<

build/states.json: build/counties.json
	node_modules/.bin/topojson-merge \
		-o $@ \
		--in-object=counties \
		--out-object=states \
		--key='d.id.substring(0, 2)' \
		-- $<

us.json: build/states.json
	node_modules/.bin/topojson-merge \
		-o $@ \
		--in-object=states \
		--out-object=nation \
		-- $<

package.json

{
  "name": "anonymous",
  "private": true,
  "version": "0.0.1",
  "dependencies": {
    "topojson": "1"
  }
}