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//
// Script that generates r-trees for geo data.
// run with `npm exec ts-node geo-data/prepare-rtree.ts`
//
import * as fs from 'fs';
import * as path from 'path';
import { Topology, GeometryCollection } from 'topojson-specification';
import rbush from 'rbush';
interface GeometryTopologyObjects {
[key: string]: any;
geometry: GeometryCollection;
}
function main() {
const GEOMETRY_DATA_FILES = ['geometry', 'states-provinces-lines'];
const OUTPUT_DIR = path.join(__dirname, 'out');
for (const name of GEOMETRY_DATA_FILES) {
const source = path.join(OUTPUT_DIR, `${name}.json`);
const destination = path.join(OUTPUT_DIR, `${name}.rbush.json`);
try {
processGeometry(source, destination);
} catch (e) {
const error = e as Error;
console.error(`Failed to process ${name}: ${error.message}`);
}
}
}
function processGeometry(source: string, destination: string) {
const collection = JSON.parse(
fs.readFileSync(source, { encoding: 'utf8' }),
) as Topology<GeometryTopologyObjects>;
const { geometry } = collection.objects;
const treeData = geometry.geometries.map((object, i) => {
if (!object.bbox) {
throw new Error(`Expected a geometry at index ${i} to have a bbox property.`);
}
const [minX, minY, maxX, maxY] = object.bbox;
return {
...object,
minX,
minY,
maxX,
maxY,
};
});
const tree = rbush();
tree.load(treeData);
fs.writeFileSync(destination, JSON.stringify(tree.toJSON()));
console.log(`Saved a rbush to ${destination}`);
}
main();
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