D3 Examples - Choropleth with svg filter

Choropleth with svg filter
Merges features based on quantized employment level. Adds an svg filter to each merged features level. It also builds the features layer by layer to ensure that shadows seem consistent.
Looks nice, but quite slow to load due to the filters.
xxxxxxxxxx
 
<!DOCTYPE html>
<meta charset="utf-8">
<style>
​
.counties {
  fill: none;
  stroke: none;
}
​
.states {
  fill: none;
  stroke-width: 0.2;
  stroke: rgb(8,48,107);
  stroke-linejoin: round;
}
​
.q0-9 { fill:rgb(247,251,255); 
  stroke-width: 0.2;
  stroke: rgb(222,235,247);
  stroke-linejoin: round;}
  
.q1-9 { fill:rgb(222,235,247); 
  stroke-width: 0.2;
  stroke: rgb(198,219,239);
  stroke-linejoin: round;}
  
.q2-9 { fill:rgb(198,219,239); 
  stroke-width: 0.2;
  stroke: rgb(158,202,225);
  stroke-linejoin: round;}
  
.q3-9 { fill:rgb(158,202,225); 
  stroke-width: 0.2;
  stroke: rgb(107,174,214);
  stroke-linejoin: round;}
  
.q4-9 { fill:rgb(107,174,214); 
  stroke-width: 0.2;
  stroke: rgb(66,146,198);
  stroke-linejoin: round;}
  
.q5-9 { fill:rgb(66,146,198); 
  stroke-width: 0.2;
  stroke: rgb(33,113,181);
  stroke-linejoin: round;}
  
.q6-9 { fill:rgb(33,113,181); 
  stroke-width: 0.2;
  stroke: rgb(8,81,156);
  stroke-linejoin: round;}
  
.q7-9 { fill:rgb(8,81,156); 
  stroke-width: 0.2;
  stroke: rgb(8,48,107);
  stroke-linejoin: round;}
  
.q8-9 { fill:rgb(8,48,107); 
  stroke-width: 0.2;
  stroke: rgb(8,48,107);
  stroke-linejoin: round;
}
​
​
</style>
<body>
<script src="https://d3js.org/d3.v3.min.js"></script>
<script src="https://d3js.org/queue.v1.min.js"></script>
<script src="https://d3js.org/topojson.v1.min.js"></script>
​
<svg class="svg1" width="960px" height="600px" version="1.1"
     xmlns="https://www.w3.org/2000/svg" xmlns:xlink="https://www.w3.org/1999/xlink">
  <defs>
    <filter id="f3" x="-0.1" y="-0.1" width="400%" height="400%">
      <feOffset result="offOut" in="SourceAlpha" dx="1" dy="1"></feOffset>
      <feGaussianBlur result="blurOut" in="offOut" stdDeviation="1"></feGaussianBlur>
      <feBlend in="SourceGraphic" in2="blurOut" mode="normal"></feBlend>
    </filter>
  </defs>
</svg>
<script>
​
var width = 960,
    height = 600;
​
var rateById = d3.map();
​
var quantize = d3.scale.quantize()
    .domain([0, .15])
    .range(d3.range(9).map(function(i) { return "q" + i + "-9"; }));
​
var projection = d3.geo.albersUsa()
    .scale(1280)
    .translate([width / 2, height / 2]);
​
var path = d3.geo.path()
    .projection(projection);
​
var svg = d3.select(".svg1");
​
queue()
    .defer(d3.json, "/../../data/us.json")
    .defer(d3.tsv, "/mbostock/raw/4060606/unemployment.tsv", function(d) { rateById.set(d.id, +d.rate); })
    .await(ready);
​
function ready(error, us) {
​
var counties = topojson.feature(us, us.objects.counties),
    selection0 = {type: "FeatureCollection", features: counties.features.filter(function(d) { return quantize(rateById.get(d.id)) == "q0-9"; })},
    selection1 = {type: "FeatureCollection", features: counties.features.filter(function(d) { return quantize(rateById.get(d.id)) == "q1-9"; })},
    selection2 = {type: "FeatureCollection", features: counties.features.filter(function(d) { return quantize(rateById.get(d.id)) == "q2-9"; })},
    selection3 = {type: "FeatureCollection", features: counties.features.filter(function(d) { return quantize(rateById.get(d.id)) == "q3-9"; })},
    selection4 = {type: "FeatureCollection", features: counties.features.filter(function(d) { return quantize(rateById.get(d.id)) == "q4-9"; })},
    selection5 = {type: "FeatureCollection", features: counties.features.filter(function(d) { return quantize(rateById.get(d.id)) == "q5-9"; })},
    selection6 = {type: "FeatureCollection", features: counties.features.filter(function(d) { return quantize(rateById.get(d.id)) == "q6-9"; })},
    selection7 = {type: "FeatureCollection", features: counties.features.filter(function(d) { return quantize(rateById.get(d.id)) == "q7-9"; })},
    selection8 = {type: "FeatureCollection", features: counties.features.filter(function(d) { return quantize(rateById.get(d.id)) == "q8-9"; })};
​
  svg.append("path")
      .datum(selection0)
      .attr("class", "q0-9")
      .attr("d", path)
      .attr("filter","url(#f3)");
    
  svg.append("path")
      .datum(selection1)
      .attr("class", "q1-9")
      .attr("d", path)
      .attr("filter","url(#f3)");
​
  svg.append("path")
      .datum(selection2)
      .attr("class", "q2-9")
      .attr("d", path)
      .attr("filter","url(#f3)");
​
  svg.append("path")
      .datum(selection3)
      .attr("class", "q3-9")
      .attr("d", path)
      .attr("filter","url(#f3)");
​
  svg.append("path")
      .datum(selection4)
      .attr("class", "q4-9")
      .attr("d", path)
      .attr("filter","url(#f3)");
​
  svg.append("path")
      .datum(selection5)
      .attr("class", "q5-9")
      .attr("d", path)
      .attr("filter","url(#f3)");
​
  svg.append("path")
      .datum(selection6)
      .attr("class", "q6-9")
      .attr("d", path)
      .attr("filter","url(#f3)");
​
  svg.append("path")
      .datum(selection7)
      .attr("class", "q7-9")
      .attr("d", path)
      .attr("filter","url(#f3)");
​
  svg.append("path")
      .datum(selection8)
      .attr("class", "q8-9")
      .attr("d", path)
      .attr("filter","url(#f3)");     
​
  svg.append("path")
      .datum(topojson.mesh(us, us.objects.states, function(a, b) { return a !== b; }))
      .attr("class", "states")
      .attr("d", path); 
      
}
​
d3.select(self.frameElement).style("height", height + "px");
​
</script>
​
​
</body>
    