| license: gpl-3.0 |
Created via the U.S. Atlas project as make topo/ky-counties.json, after modifying the Makefile to include population and area statistics. These per-county values are then used to compute the population density of each county.
topojson \
--id-property=FIPS,STATE_FIPS \
-p name=COUNTY,name=STATE,+population,area=+SQUARE_MIL \
-e KY-counties-pop.csv \
-- shp/ky/counties.shp shp/ky/states.shpColors by ColorBrewer.
| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <style> | |
| svg { | |
| font: 10px sans-serif; | |
| } | |
| .caption { | |
| font-weight: bold; | |
| } | |
| .key path { | |
| display: none; | |
| } | |
| .key line { | |
| stroke: #000; | |
| shape-rendering: crispEdges; | |
| } | |
| .county { | |
| fill: #eee; | |
| } | |
| .county-border { | |
| fill: none; | |
| stroke: #fff; | |
| } | |
| .state-border { | |
| fill: none; | |
| stroke: #333; | |
| } | |
| </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 = 500; | |
| var color = d3.scale.threshold() | |
| .domain([30, 60, 120, 360]) | |
| .range(["#ffffcc","#c2e699","#78c679","#31a354","#006837"]); | |
| // A position encoding for the key only. | |
| var x = d3.scale.linear() | |
| .domain([0, 390]) | |
| .range([0, 240]); | |
| var xAxis = d3.svg.axis() | |
| .scale(x) | |
| .orient("bottom") | |
| .tickSize(13) | |
| .tickValues(color.domain()); | |
| // Kentucky State Plane, Single Zone | |
| // ftp://kygeonet.ky.gov/kygeodata/standards/Ky_StatePlane.pdf | |
| var projection = d3.geo.conicConformal() | |
| .rotate([85 + 45 / 60, -36 - 20 / 60]) | |
| .parallels([37 + 05 / 60, 38 + 40 / 60]) | |
| .scale(7090) | |
| .center([-0.04940, 1.50406]) | |
| .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); | |
| var g = svg.append("g") | |
| .attr("class", "key") | |
| .attr("transform", "translate(40,40)"); | |
| g.selectAll("rect") | |
| .data(color.range().map(function(d, i) { | |
| return { | |
| x0: i ? x(color.domain()[i - 1]) : x.range()[0], | |
| x1: i < color.domain().length ? x(color.domain()[i]) : x.range()[1], | |
| z: d | |
| }; | |
| })) | |
| .enter().append("rect") | |
| .attr("height", 8) | |
| .attr("x", function(d) { return d.x0; }) | |
| .attr("width", function(d) { return d.x1 - d.x0; }) | |
| .style("fill", function(d) { return d.z; }); | |
| g.call(xAxis).append("text") | |
| .attr("class", "caption") | |
| .attr("y", -6) | |
| .text("Population per square mile"); | |
| d3.json("ky-counties.json", function(error, ky) { | |
| if (error) throw error; | |
| var counties = topojson.feature(ky, ky.objects.counties); | |
| svg.append("g") | |
| .attr("class", "county") | |
| .selectAll("path") | |
| .data(counties.features) | |
| .enter().append("path") | |
| .attr("d", path) | |
| .style("fill", function(d) { return color(d.density = d.properties.population / d.properties.area); }) | |
| .append("title") | |
| .text(function(d) { return d.properties.name + ": " + d.density.toFixed(0) + "/mi.²"; }); | |
| svg.append("path") | |
| .datum(topojson.mesh(ky, ky.objects.counties, function(a, b) { return a !== b; })) | |
| .attr("class", "county-border") | |
| .attr("d", path); | |
| svg.append("path") | |
| .datum(topojson.mesh(ky, ky.objects.counties, function(a, b) { return a === b; })) | |
| .attr("class", "state-border") | |
| .attr("d", path); | |
| }); | |
| </script> |
