Maps — and other representations of the world.
cities = FileAttachment("cities.csv").csv({ typed: true })
cityRadius = (population) => 0.035 * Math.pow(population, 0.44)
pop = cities.find((d) => d.city === highlightedCity).population
albers = d3.geoAlbersUsa().scale(1300).translate([487.5, 305])
scale = {
const ny = cities.find((d) => d.city === "New York");
const sf = cities.find((d) => d.city === "San Francisco");
const nyp = albers([ny.lon, ny.lat]);
const sfp = albers([sf.lon, sf.lat]);
return Math.hypot(nyp[0] - sfp[0], nyp[1] - sfp[1]) / 4100;
}
projection = d3.geoIdentity().fitExtent(
[
[0, 0],
[width, height]
],
counties
)
nation = topojson.feature(us, us.objects.nation)
states = topojson.mesh(us, us.objects.states)
counties = topojson.feature(us, us.objects.counties)
import { us } from "@d3/choropleth"
function map() {
const context = DOM.context2d(width, height);
context.fillStyle = fillBackground;
context.fillRect(0, 0, width, height);
const projection = d3.geoIdentity().fitExtent(
[
[0, 0],
[width, height]
],
nation
);
const path = d3.geoPath(projection, context);
context.beginPath();
path(nation);
context.fillStyle = fillNation;
context.fill();
context.stroke();
context.clip();
context.beginPath();
path(states);
context.lineWidth = 0.75;
context.stroke();
context.lineWidth = 0.25;
for (const { fill, mult, layer } of [
{ fill: fillRegion, mult: 8 },
{ fill: fillZone, mult: 2.5, layer: true },
{ fill: fillCity, mult: 1 }
]) {
context.beginPath();
for (const { lon, lat, population } of cities) {
const r = mult * cityRadius(population) * scale;
const a = albers([lon, lat]);
if (!a) continue;
const p = projection(a);
context.moveTo(p[0] + r, p[1]);
context.arc(...p, r, 0, 2 * Math.PI);
}
context.fillStyle = fill;
context.fill();
context.strokeStyle = fill;
context.stroke();
if (layer) {
context.beginPath();
path(counties);
context.lineWidth = 0.25;
context.strokeStyle = "black";
context.stroke();
}
}
return context.canvas;
}
height = 600
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