Topographic MappingBubble mapAccess to Family planningMD Counties Total Cases MapTendance de la production des déchets en Union EuropéenneAndy's Walgreens COVID-19 Tracker TrackerElection Maps for Incomplete ResultsA better U.S. house election results map?1983 Mayoral Election, Dot density mapsMastodon 🐘Cheat sheet bertinBertin.js: regular squaresWaterlinesNeumorphism Contour Density MapCartographic DoodlesStars and constellationsPlot: Grid choroplethHello Polygon MorphingMapping with pie chartsU.S. Geographic DataHow big are countries... like really!AttitudeB&W ChoroplethWeb Mercator Tile VisibilityMARTINI: Real-Time RTIN Terrain Mesh"Magnifying-Glass" projectionsTissot's indicatrixAntipodal mapMapping gridded data with a Voronoi diagramA Map of Every BuildingUrbano Monti’s Planisphere (1587)Bivariate choroplethDIY HillshadeMapbox Map MakerWorld tourHillshaderSimplified Earth with curved shapesHexbin mapInner glowNicolosi vs. StereographicData-driven projections: Darwin's worldSatellite ground track visualizerDirection to shoreHello, OpenLayers!U.S. airports VoronoiHello, NYC Geosearch API!Mapbox Fly-ToSpilhaus shoreline mapWalmart’s growthHow well does population density predict U.S. voting outcomes?Drawing maps from geodata with D3 & ObservableHexgrid maps with d3-hexgridTissot's indicatrixWorld airports VoronoiSwiss Elevation Line GraphsVector tilesVersor draggingOrthographicSolar TerminatorStreaming ShapefilesFake GlobesPeirce Quincuncial🍃 LeafletU.S.G.S. World Earthquake MapUsing Mapbox GL JSUsing Google Maps
Choropleth
chart = {
const color = d3.scaleQuantize([1, 10], d3.schemeBlues[9]);
const path = d3.geoPath();
const format = d => `${d}%`;
const valuemap = new Map(data.map(d => [d.id, d.rate]));
// The counties feature collection is all U.S. counties, each with a
// five-digit FIPS identifier. The statemap lets us lookup the name of
// the state that contains a given county; a state’s two-digit identifier
// corresponds to the first two digits of its counties’ identifiers.
const counties = topojson.feature(us, us.objects.counties);
const states = topojson.feature(us, us.objects.states);
const statemap = new Map(states.features.map(d => [d.id, d]));
// The statemesh is just the internal borders between states, i.e.,
// everything but the coastlines and country borders. This avoids an
// additional stroke on the perimeter of the map, which would otherwise
// mask intricate features such as islands and inlets. (Try removing
// the last argument to topojson.mesh below to see the effect.)
const statemesh = topojson.mesh(us, us.objects.states, (a, b) => a !== b);
const svg = d3.create("svg")
.attr("width", 975)
.attr("height", 610)
.attr("viewBox", [0, 0, 975, 610])
.attr("style", "max-width: 100%; height: auto;");
svg.append("g")
.attr("transform", "translate(610,20)")
.append(() => Legend(color, {title: "Unemployment rate (%)", width: 260}));
svg.append("g")
.selectAll("path")
.data(topojson.feature(us, us.objects.counties).features)
.join("path")
.attr("fill", d => color(valuemap.get(d.id)))
.attr("d", path)
.append("title")
.text(d => `${d.properties.name}, ${statemap.get(d.id.slice(0, 2)).properties.name}\n${valuemap.get(d.id)}%`);
svg.append("path")
.datum(topojson.mesh(us, us.objects.states, (a, b) => a !== b))
.attr("fill", "none")
.attr("stroke", "white")
.attr("stroke-linejoin", "round")
.attr("d", path);
return svg.node();
}
data = (await FileAttachment("unemployment-x.csv").csv()).map((d) => (d.rate = +d.rate, d))
us = FileAttachment("counties-albers-10m.json").json() // https://github.com/topojson/us-atlas
import {Legend} from "@d3/color-legend"
Plot.plot({
projection: "identity",
width: 975,
height: 610,
color: {scheme: "Blues", type: "quantize", n: 9, domain: [1, 10], label: "Unemployment rate (%)", legend: true},
marks: [
Plot.geo(topojson.feature(us, us.objects.counties), {fill: (map => d => map.get(d.id))(new Map(data.map(d => [d.id, d.rate])))}),
Plot.geo(topojson.mesh(us, us.objects.states, (a, b) => a !== b), {stroke: "white"})
]
})
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
