Public
Edited
Dec 15, 2023
1 fork
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
Insert cell
{
const a = mapLastClick;
const m = chart.mapPixelsToLocations;
let val = "-";
const k = a.join("_");
if (m.has(k)) {
val = m.get(k);
}
return `${k} ${val}`;
}
Insert cell
viewof mapLastClick = chart.setLocations(locationsTwo).run().canvas
Insert cell
chart = {
const context = DOM.context2d(width, height);
const canvas = context.canvas;
const path = d3.geoPath(projection, context);
let locations = [];
const mapPixelsToLocations = new Map();
let selection;
let api;

context.canvas.addEventListener(
"click",
({ pointerId, clientX, clientY, pressure }) => {
canvas.value = [clientX, clientY];
canvas.dispatchEvent(new CustomEvent("input"));
}
);

function drawLocations() {
for (const c of locations) {
const position = projection(c);
const [x, y] = position;
mapPixelsToLocations.set(`${x}_${y}`, c);
context.strokeStyle = "tomato";
context.beginPath();
// arc(x, y, radius, startAngle, endAngle)
context.arc(x, y, 5, 0, 2 * Math.PI);
context.fillStyle = "tomato";
context.fill();
}
}

function render(land) {
context.clearRect(0, 0, width, height);
context.beginPath(),
path(sphere),
(context.fillStyle = "white"),
context.fill();
context.beginPath(),
path(land),
(context.strokeStyle = "black"),
context.stroke(),
(context.fillStyle = "aliceBlue"),
context.fill();

context.save();
drawLocations(locations);
context.restore();
}

function setLocations(locs) {
locations = locs;
return api;
}

function run() {
selection = d3
.select(context.canvas)
.call(
zoom(projection)
.on("zoom.render", () => render(countries))
.on("end.render", () => render(countries))
)
.call(() => render(countries));
return api;
}

run();

api = Object.assign(selection, {
setLocations,
run,
canvas,
mapPixelsToLocations
});

return api;
}
Insert cell
locations = [
[-79.9399309, 32.7884363], // chs
[2.1774322, 41.3828939] // bcn
]
Insert cell
locationsTwo = [
[-74.006, 40.7128], // New York City, USA
[-118.2437, 34.0522], // Los Angeles, USA
[-0.1278, 51.5074], // London, UK
[139.6917, 35.6895], // Tokyo, Japan
[151.2093, -33.8688] // Sydney, Australia
]
Insert cell
function zoom(
projection,
{
// Capture the projection’s original scale, before any zooming.
scale = projection._scale === undefined
? (projection._scale = projection.scale())
: projection._scale,
scaleExtent = [0.8, 20],
translate = projection
.translate()
.map((d) => d / (projection.scale() / scale))
} = {}
) {
const zoom = d3
.zoom()
.scaleExtent(scaleExtent.map((x) => x * scale))
.on("start", zoomstarted)
.on("zoom", zoomed);

function zoomstarted() {}

function zoomed(event) {
const { k, x, y } = event.transform;
projection
.scale(k)
.translate([
translate[0] * (k / scale) + x,
translate[1] * (k / scale) + y
]);
}

return Object.assign(
(selection) =>
selection
.property("__zoom", d3.zoomIdentity.scale(projection.scale()))
.call(zoom),
{
on(type, ...options) {
return options.length
? (zoom.on(type, ...options), this)
: zoom.on(type);
},
filter() {
return zoom.filter(...arguments), this;
}
}
);
}
Insert cell
projection = d3[projectionName]().precision(0.1)
Insert cell
sphere = ({type: "Sphere"})
Insert cell
land50 = FileAttachment("land-50m.json").json().then(world => topojson.feature(world, world.objects.land))
Insert cell
land110 = FileAttachment("land-110m.json").json().then(world => topojson.feature(world, world.objects.land))
Insert cell
topojson = require("topojson-client@3")
Insert cell
d3 = require("d3@6")
Insert cell
countries = {
const data = await FileAttachment("countries-mike@2.json").json();
return data;
}
Insert cell

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.
Learn more