Choropleth V5

5.x implementation of a choropleth map, using Promises.

Forked from mbostock's block: Choropleth

forked from adamjanes's block: Choropleth V5

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

.counties {
  fill: none;
}

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

</style>
<svg width="960" height="600"></svg>
<script src="https://d3js.org/d3.v5.min.js"></script>
<script src="https://d3js.org/d3-scale-chromatic.v1.min.js"></script>
<script src="https://d3js.org/topojson.v2.min.js"></script>
<script>

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

var unemployment = d3.map();

var path = d3.geoPath();

var x = d3.scaleLinear()
    .domain([1, 10])
    .rangeRound([600, 650]);

var color = d3.scaleLinear()
//     .domain(d3.range(-50, 0, 5))
    .domain([-50,
             -45,-40,-35,-30,-25,-20,-15,-10,-5, 
             0
            ])
    .range(["#890024",
            "#A94138",
            "#C86E4F",
            "#E19E6F",
            "#F2CD97",
            "#FFFFC2",
            "#CCDCB5",
            "#98BAA8",
            "#6A9799",
            "#447586",
            "#195473",
            "#195473"
        ])
.clamp(true);

var g = svg.append("g")
    .attr("class", "key")
    .attr("transform", "translate(0,40)");

// g.selectAll("rect")
//   .data(color.range().map(function(d) {
//       d = color.invertExtent(d);
//       if (d[0] == null) d[0] = x.domain()[0];
//       if (d[1] == null) d[1] = x.domain()[1];
//       return d;
//     }))
//   .enter().append("rect")
//     .attr("height", 8)
//     .attr("x", function(d) { return x(d[0]); })
//     .attr("width", function(d) { return x(d[1]) - x(d[0]); })
//     .attr("fill", function(d) { return color(d[0]); });

// g.append("text")
//     .attr("class", "caption")
//     .attr("x", x.range()[0])
//     .attr("y", -6)
//     .attr("fill", "#000")
//     .attr("text-anchor", "start")
//     .attr("font-weight", "bold")
//     .text("Unemployment rate");

// g.call(d3.axisBottom(x)
//     .tickSize(13)
//     .tickFormat(function(x, i) { return i ? x : x + "%"; })
//     .tickValues(color.domain()))
//   .select(".domain")
//     .remove();

var promises = [
  d3.json("https://d3js.org/us-10m.v1.json"),
  d3.tsv("unemployment.tsv", function(d) { unemployment.set(d.id, +d.rate); })
]

Promise.all(promises).then(ready)

function ready([us]) {
  svg.append("g")
      .attr("class", "counties")
    .selectAll("path")
    .data(topojson.feature(us, us.objects.counties).features)
    .enter().append("path")
      .attr("fill", function(d) { return color(d.rate = unemployment.get(d.id)); })
      .attr("d", path)
    .append("title")
      .text(function(d) { return d.rate + "%"; });

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

</script>

https://d3js.org/d3.v5.min.js

https://d3js.org/d3-scale-chromatic.v1.min.js

https://d3js.org/topojson.v2.min.js