contours = d3
.contours()
.size([n, m])
.smooth(true)
.thresholds(new Array(5).fill(null).map((_, i) => 55 + i * 20))
contoursWithThresholds = contours(values)
function reproject(shape) {
let reprojectedShape = { ...shape };
reprojectedShape.coordinates = reprojectedShape.coordinates.map((polygon) => {
return polygon.map((rings) => {
return rings.map((coordinate) => {
return pixelToGeo(coordinate);
return projection.invert(coordinate);
});
});
});
return reprojectedShape;
// return projections.geoStitch(reprojectedShape);
// return projections.geoQuantize(reprojectedShape, 4);
// return projections.geoStitch(projections.geoQuantize(reprojectedShape, 2));
}
values = {
let image = await imagePromise();
let values = [];
const data = image.data;
for (let i = 0; i < data.length; i += 4) {
data[i] = 255 - data[i]; // R
data[i + 1] = 255 - data[i + 1]; // G
data[i + 2] = 255 - data[i + 2]; // B
let r = 255 - data[i];
let g = 255 - data[i + 1];
let b = 255 - data[i + 2];
let color = `${r}-${g}-${b}`;
let value = colors[color] || 0;
values.push(value);
}
// return values;
return d3.blur2({ data: values, width: n }, 0.5).data;
}
m = image.naturalHeight
n = image.naturalWidth
// https://aviationweather.gov/wafs/ [-75.940536, -179.983902], [75.940536, 179.983902]
land = topojson.feature(world, world.objects.land)
world = FileAttachment("land-50m.json").json()
d3 = require("d3@7.6.0/dist/d3.min.js") // d3.blur was introduced in d3-array@3.2 and d3@7.6
projections = require("d3-geo-projection@2")
png = require("pngjs@5.0.0/browser.js")
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.