points = {
//Modified from https://observablehq.com/@toja/gridded-population-of-the-world
const features = [];
const { nrows, ncols, cellsize, xllcorner, yllcorner, NODATA_value } =
parsed.header;
for (let y = 0; y < nrows; y++) {
for (let x = 0; x < ncols; x++) {
/*
Raster starts in upper left hand corner and moves east then restarts one row down on the left. This is confusing because the reference coordinates are provided for the lower left hand of the raster.
*/
features.push({
type: "Feature",
geometry: {
type: "Point",
coordinates: [
x * cellsize - (-xllcorner - cellsize / 2),
-y * cellsize + (-yllcorner - cellsize / 2)
]
},
properties: {
count: parsed.data[y][x]
}
});
}
}
return {
type: "FeatureCollection",
features: features.filter(
(d) =>
(d.properties.count !== parsed.header.NODATA_value) &
(d.properties.count > 0)
)
};
}
import { parse } from "@toja/gridded-population-of-the-world"
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.
