Public
Edited
Apr 25, 2023
2 stars
function hexgridGeoPlot(
data = [],
{
/*
* Required
*/
features, // The GeoJSON of main feature
position = (d) => [d.lon, d.lat], // given d in data, returns the [longitude, latitude]
/*
* Optional
*/
width = 640,
height = 400,
// ⚠️ Apply rotation to the projection if needed.
// d3.geoTransverseMercator() is good for showing a country or smalles area
// d3.geoWinkel3() or d3.geoEqualEarth() is good to show larger area
projection = d3.geoIdentity().reflectY(true).fitWidth(width, geo),
padding = width / 50,
hexagonRadius = 10, // In km,
scale = d3.scaleSequential,
range = interpolateGrBu,
domain,
nice = true, // applies nice() on scale if available
drawBorder = true,
unknown = "#ccc",
ignorePointsOutsideGeoJson = false, // don't plot bins outside the provided GeoJSON
// Legend
showLegend = true,
legendTitle,
legendWidth = Math.max(120, width / 7),
ticks,
tickFormat = ".0f",
tickSize = 0,
// Accessors
binValue = (d) => d.datapoints,
binTitle = (d) => d.datapoints,
debug = false
}
) {
// Scales
projection = projection.scale === undefined ? projection() : projection;
projection.fitExtent(
[
[padding, padding],
[width - padding, height - padding]
],
features
);
const pathGenerator = d3.geoPath(projection);
if (ignorePointsOutsideGeoJson) {
data = data.map((d) => {
const [x, y] = projection([d.lon, d.lat]);
return {
...d,
x,
y
};
});
const poly = d3hg.geoPolygon(features, projection);
data = d3hg.polygonPoints(data, poly);
}
const hexgrid = d3hg
.hexgrid()
.extent([width, height])
.geography(features)
.projection(projection)
.hexRadius(hexagonRadius, "km")
.pathGenerator(pathGenerator);
const hex = hexgrid(data, ["name"]);
if (domain === undefined) {
domain = d3.extent(hex.grid.layout, binValue);
if (scale === d3.scaleQuantile) {
domain = hex.grid.layout.map((d) => binValue(d));
}
}
let color = scale(domain, range);
if (nice && typeof color.nice === "function") {
color = color.copy().nice();
}
if (color.unknown && unknown !== undefined) color.unknown(unknown);
// Draw
const svg = DOM.svg(width, height);
d3.select(svg)
.attr("style", "max-width: 100%; height: auto; height: intrinsic;")
.style("background", "white");
if (debug) {
d3.select(svg)
.selectAll(".boundary")
.data(features.features)
.join("path")
.classed("boundary", true)
.attr("d", pathGenerator)
.attr("fill", "#ff0");
}
const bins = d3
.select(svg)
.append("g")
.classed("hexbins", true)
.selectAll("path")
.data(hex.grid.layout)
.join("path")
.attr("d", hex.hexagon())
.attr("transform", (d) => `translate(${d.x} ${d.y})`)
.attr("fill", (d) => color(binValue(d)))
.attr("stroke", (d) => d3.lab(color(binValue(d))).brighter())
.attr("stroke-width", () => (drawBorder ? 0.5 : 0))
.append("title")
.text(binTitle);
if (debug) {
d3.select(svg)
.append("g")
.classed("features", true)
.selectAll("circle")
.data(data)
.join("circle")
.attr(
"transform",
(d) => `translate(${projection(position(d)).join(",")})`
)
.attr("r", 0.75)
.attr("fill", "#f0f")
.attr("stroke", "none");
}
if (showLegend) {
d3.select(svg)
.append("g")
.attr("transform", `translate(${width - legendWidth - padding}, ${padding})`)
.append(() =>
legend({
color,
title: legendTitle,
width: legendWidth,
ticks,
tickFormat,
tickSize
})
);
}
return svg;
}
One platform to build and deploy the best data apps
Experiment and prototype by building visualizations in live JavaScript notebooks. Collaborate with your team and decide which concepts to build out.
Use Observable Framework to build data apps locally. Use data loaders to build in any language or library, including Python, SQL, and R.
Seamlessly deploy to Observable. Test before you ship, use automatic deploy-on-commit, and ensure your projects are always up-to-date.