| license: gpl-3.0 |
Note: the counties aren’t clipped to water boundaries, so they look a bit weird and the corresponding density calculation is inaccurate. So don’t copy this example without fixing those problems first, ok? See the us-atlas project for a more comprehensive Makefile of examples, and the projected choropleth example for a better style. Also, you’ll want to add a legend for the color scale.
To build this example, git clone this repo, npm install, and then make.
| <!DOCTYPE html> | |
| <meta charset="utf-8"> | |
| <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.log() | |
| .range(["hsl(62,100%,90%)", "hsl(228,30%,20%)"]) | |
| .interpolate(d3.interpolateHcl); | |
| var path = d3.geo.path() | |
| .projection(null); | |
| var svg = d3.select("body").append("svg") | |
| .attr("width", width) | |
| .attr("height", height); | |
| d3.json("us-albers.json", function(error, us) { | |
| if (error) throw error; | |
| var counties = topojson.feature(us, us.objects.counties).features; | |
| var densities = counties | |
| .map(function(d) { return d.properties.density = d.properties.pop / path.area(d); }) | |
| .sort(function(a, b) { return a - b; }); | |
| color.domain([d3.quantile(densities, .01), d3.quantile(densities, .99)]); | |
| svg.append("g") | |
| .attr("class", "counties") | |
| .selectAll("path") | |
| .data(counties) | |
| .enter().append("path") | |
| .style("fill", function(d) { return color(d.properties.density); }) | |
| .attr("d", path); | |
| }); | |
| </script> |
| all: \ | |
| us-albers.json | |
| clean: | |
| rm -rf -- County_2010Census_DP1.* | |
| County_2010Census_DP1.zip: | |
| curl -o $@ --raw 'http://www2.census.gov/geo/tiger/TIGER2010DP1/County_2010Census_DP1.zip' | |
| County_2010Census_DP1.shp: County_2010Census_DP1.zip | |
| rm -rf $(basename $@) | |
| mkdir -p $(basename $@) | |
| unzip -d $(basename $@) $< | |
| for file in $(basename $@)/*; do chmod 644 $$file; mv $$file $(basename $@).$${file##*.}; done | |
| rmdir $(basename $@) | |
| touch $@ | |
| # projected (giving node extra memory since input shapefile is big) | |
| us-albers.json: County_2010Census_DP1.shp | |
| node --max_old_space_size=8192 node_modules/.bin/topojson \ | |
| -q 1e5 \ | |
| -s 1 \ | |
| --projection 'd3.geo.albersUsa()' \ | |
| --id-property=GEOID10 \ | |
| -p name=NAMELSAD10,pop=+DP0010001 \ | |
| -o $@ \ | |
| -- counties=County_2010Census_DP1.shp | |
| # non-projected (not used by this example, but included for reference) | |
| us.json: County_2010Census_DP1.shp | |
| node_modules/.bin/topojson \ | |
| -q 1e5 \ | |
| -s 7e-7 \ | |
| --id-property=GEOID10 \ | |
| -p name=NAMELSAD10,pop=+DP0010001 \ | |
| -o $@ \ | |
| -- counties=County_2010Census_DP1.shp |
| { | |
| "name": "anonymous", | |
| "version": "0.0.1", | |
| "private": true, | |
| "devDependencies": { | |
| "topojson": "1" | |
| } | |
| } |
