H3 Tutorial: Intro to h3-js (v4)Indexing Polygons With H3Cell counts per countryH3 Adaptive GridH3 Index Bit LayoutH3 Hierarchical (Non)ContainmentH3 Deck.gl Heat MapH3 Mapbox Style Heat MapIndexing OrderArea VariationH3 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
H3 Continuous Elevation
md`*zoom:* ${mapView.getZoom().toFixed(2)} *h3 res:* ${zoomToResolution(mapView.getZoom())}`
{
const map = mapView;
const {min, max} = elevationDomain;
renderMapLayer({
map,
id: 'grid',
data: h3Features,
type: 'fill',
paint: {
'fill-color': {
"property": "elevation",
"stops": [
[min, 'blue'],
[max, 'red']
]
},
'fill-outline-color': 'rgba(0,0,0,0)',
'fill-opacity': 0.5
}
});
renderMapLayer({
map,
id: 'tile-bounds',
data: tileFeatures,
type: 'line',
paint: {
'line-color': 'grey',
'line-opacity': 0.5
}
})
return md`*{map rendering logic}*`
}
tiles = {
const mapBounds = mapView.getBounds();
const zoom = Math.floor(mapView.getZoom());
return getTiles(mapBounds, zoom);
}
tileToIndexes = (tile, dem) => {
const {minLat, maxLat, minLng, maxLng} = tileBounds(tile);
const height = maxLat - minLat;
const width = maxLng - minLng;
const rowCount = dem.length;
const colCount = dem[0].length;
const px2coord = (row, col) => ({
lat: maxLat - (row / rowCount) * height,
lng: (col / colCount) * width + minLng
});
const indexes = {};
for (let r = 0; r < rowCount; r++) {
for (let c = 0; c < colCount; c++) {
const {lat, lng} = px2coord(r, c);
const h3Index = h3.geoToH3(lat, lng, zoomToResolution(tile.z));
// We don't want dupe indexes between tiles, so filter out
// indexes based on their center point
const [centerLat, centerLng] = h3.h3ToGeo(h3Index);
if (centerLat < minLat ||
centerLat >= maxLat ||
centerLng < minLng ||
centerLng >= maxLng
) continue;
if (!indexes[h3Index]) {
indexes[h3Index] = {sum: 0, count: 0};
}
indexes[h3Index].sum += dem[r][c];
indexes[h3Index].count++;
}
}
return Object.keys(indexes).map(h3Index => {
const {sum, count} = indexes[h3Index];
return {h3Index, elevation: sum / count};
})
}
getDomain = (h3Indexes) => {
let min = Infinity;
let max = -Infinity;
h3Indexes.forEach(({elevation}) => {
if (elevation > max) {
max = elevation;
}
if (elevation < min) {
min = elevation;
}
});
return {min, max};
}
zoomToResolution = (zoom) => {
const res = [0, 1, 2, 3, 4, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12];
return zoom >= res.length ? res[res.length - 1] : res[Math.floor(zoom)];
}
h3ToFeatures = (h3Indexes) => ({
type: 'FeatureCollection',
features: h3Indexes.map(({h3Index, elevation}) => ({
type: 'Feature',
id: h3Index,
properties: {h3Index, elevation},
geometry: {
type: 'Polygon',
coordinates: [h3.h3ToGeoBoundary(h3Index, true)]
}
}))
})
tilesToFeatures = (tiles) => ({
type: 'FeatureCollection',
features: tiles.map(tile => {
const {minLat, maxLat, minLng, maxLng} = tileBounds(tile);
return {
type: 'Feature',
geometry: {
type: 'Polygon',
coordinates: [[
[minLng, minLat],
[maxLng, minLat],
[maxLng, maxLat],
[minLng, maxLat],
[minLng, minLat],
]]
}
};
})
})
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.