H3 Tutorial: Intro to h3-js (v4)Cell counts per countryH3 Adaptive GridH3 Index Bit LayoutH3 Hierarchical (Non)ContainmentH3 Deck.gl Heat MapH3 Mapbox Style Heat MapIndexing OrderArea VariationH3 Continuous ElevationH3 Indexes: Cartesian vs SphericalShape simplification with H3H3 Index Inspector"Flat" H3 Grid via Gnomonic ProjectionH3 Radius LookupH3 Tutorial: Suitability AnalysisH3 Tutorial: Using Point LayersH3 Tutorial: Rendering HexagonsH3 Tutorial: Intro to h3-js (v3)H3 PathfindingSurface construction with H3
Indexing Polygons With H3
function indexPolygon(polygon) {
switch (approach.value) {
case 'fine': {
// Index the polygon at the finest resolution
return h3.polygonToCells(polygon, config.fineRes, true);
}
case 'dual': {
// Index the polygon at two resolutions, fine and coarse
const cells = h3.polygonToCells(polygon, config.fineRes, true);
const compactCells = h3.compactCells(cells);
const coarseCells = h3.uncompactCells(
compactCells.filter(cell => h3.getResolution(cell) <= config.coarseRes),
config.coarseRes
);
const fineCells = h3.uncompactCells(
compactCells.filter(cell => h3.getResolution(cell) > config.coarseRes),
config.fineRes
);
return coarseCells.concat(fineCells);
}
case 'compact': {
// Index the polygon at various resolutions
const cells = h3.polygonToCells(polygon, config.fineRes, true);
return h3.compactCells(cells);
}
}
}
resolutionsToCheck = {
switch (approach.value) {
case 'fine': {
// Check only the fine resolution, that's all that's in the index
return [config.fineRes];
}
case 'dual': {
// Check either fine or coarse resolutions
return [config.coarseRes, config.fineRes];
}
case 'compact': {
// Check all resolutions from 0 to finest
return [...Array(config.fineRes + 1).keys()]
}
}
}
function indexLookup(point) {
const finest = h3.latLngToCell(point.lat, point.lng, config.fineRes);
for (const res of resolutionsToCheck) {
// Note that we take the parent of the finest cell, *not* just latLngToCell(res).
// This is because the coarser cells represent sets of their children, not their
// own geometry, so you could get false positives or false negatives.
const lookupCell = h3.cellToParent(finest, res);
const country = index.get(lookupCell);
if (country) return country;
}
return null;
}
clickedCountry = map.point ? indexLookup(map.point) : null;
countriesTopoJson = FileAttachment("countries.json").json()
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