All docsMapbox GL JSExamplesDisplay HTML clusters with custom properties

Display HTML clusters with custom properties

This advanced example uses Mapbox GL JS clustering with HTML markers and the custom property expressions number-format, get, !=, >, >=, all, and case.

You can use HTML or SVG for clusters in place of a Mapbox GL layer by manually synchronizing the clustered source with a pool of marker objects that updates continuously while the map view changes.

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Display HTML clusters with custom properties</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v2.1.1/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v2.1.1/mapbox-gl.js"></script>
<style>
body { margin: 0; padding: 0; }
#map { position: absolute; top: 0; bottom: 0; width: 100%; }
</style>
</head>
<body>
<div id="map"></div>
<script>
// TO MAKE THE MAP APPEAR YOU MUST
// ADD YOUR ACCESS TOKEN FROM
// https://account.mapbox.com
mapboxgl.accessToken = '<your access token here>';
var map = new mapboxgl.Map({
container: 'map',
zoom: 0.3,
center: [0, 20],
style: 'mapbox://styles/mapbox/light-v10'
});
map.addControl(new mapboxgl.NavigationControl());
// filters for classifying earthquakes into five categories based on magnitude
var mag1 = ['<', ['get', 'mag'], 2];
var mag2 = ['all', ['>=', ['get', 'mag'], 2], ['<', ['get', 'mag'], 3]];
var mag3 = ['all', ['>=', ['get', 'mag'], 3], ['<', ['get', 'mag'], 4]];
var mag4 = ['all', ['>=', ['get', 'mag'], 4], ['<', ['get', 'mag'], 5]];
var mag5 = ['>=', ['get', 'mag'], 5];
// colors to use for the categories
var colors = ['#fed976', '#feb24c', '#fd8d3c', '#fc4e2a', '#e31a1c'];
map.on('load', function () {
// add a clustered GeoJSON source for a sample set of earthquakes
map.addSource('earthquakes', {
'type': 'geojson',
'data':
'https://docs.mapbox.com/mapbox-gl-js/assets/earthquakes.geojson',
'cluster': true,
'clusterRadius': 80,
'clusterProperties': {
// keep separate counts for each magnitude category in a cluster
'mag1': ['+', ['case', mag1, 1, 0]],
'mag2': ['+', ['case', mag2, 1, 0]],
'mag3': ['+', ['case', mag3, 1, 0]],
'mag4': ['+', ['case', mag4, 1, 0]],
'mag5': ['+', ['case', mag5, 1, 0]]
}
});
// circle and symbol layers for rendering individual earthquakes (unclustered points)
map.addLayer({
'id': 'earthquake_circle',
'type': 'circle',
'source': 'earthquakes',
'filter': ['!=', 'cluster', true],
'paint': {
'circle-color': [
'case',
mag1,
colors[0],
mag2,
colors[1],
mag3,
colors[2],
mag4,
colors[3],
colors[4]
],
'circle-opacity': 0.6,
'circle-radius': 12
}
});
map.addLayer({
'id': 'earthquake_label',
'type': 'symbol',
'source': 'earthquakes',
'filter': ['!=', 'cluster', true],
'layout': {
'text-field': [
'number-format',
['get', 'mag'],
{ 'min-fraction-digits': 1, 'max-fraction-digits': 1 }
],
'text-font': ['Open Sans Semibold', 'Arial Unicode MS Bold'],
'text-size': 10
},
'paint': {
'text-color': [
'case',
['<', ['get', 'mag'], 3],
'black',
'white'
]
}
});
// objects for caching and keeping track of HTML marker objects (for performance)
var markers = {};
var markersOnScreen = {};
function updateMarkers() {
var newMarkers = {};
var features = map.querySourceFeatures('earthquakes');
// for every cluster on the screen, create an HTML marker for it (if we didn't yet),
// and add it to the map if it's not there already
for (var i = 0; i < features.length; i++) {
var coords = features[i].geometry.coordinates;
var props = features[i].properties;
if (!props.cluster) continue;
var id = props.cluster_id;
var marker = markers[id];
if (!marker) {
var el = createDonutChart(props);
marker = markers[id] = new mapboxgl.Marker({
element: el
}).setLngLat(coords);
}
newMarkers[id] = marker;
if (!markersOnScreen[id]) marker.addTo(map);
}
// for every marker we've added previously, remove those that are no longer visible
for (id in markersOnScreen) {
if (!newMarkers[id]) markersOnScreen[id].remove();
}
markersOnScreen = newMarkers;
}
// after the GeoJSON data is loaded, update markers on the screen on every frame
map.on('render', function () {
if (!map.isSourceLoaded('earthquakes')) return;
updateMarkers();
});
});
// code for creating an SVG donut chart from feature properties
function createDonutChart(props) {
var offsets = [];
var counts = [
props.mag1,
props.mag2,
props.mag3,
props.mag4,
props.mag5
];
var total = 0;
for (var i = 0; i < counts.length; i++) {
offsets.push(total);
total += counts[i];
}
var fontSize =
total >= 1000 ? 22 : total >= 100 ? 20 : total >= 10 ? 18 : 16;
var r = total >= 1000 ? 50 : total >= 100 ? 32 : total >= 10 ? 24 : 18;
var r0 = Math.round(r * 0.6);
var w = r * 2;
var html =
'<div><svg width="' +
w +
'" height="' +
w +
'" viewbox="0 0 ' +
w +
' ' +
w +
'" text-anchor="middle" style="font: ' +
fontSize +
'px sans-serif; display: block">';
for (i = 0; i < counts.length; i++) {
html += donutSegment(
offsets[i] / total,
(offsets[i] + counts[i]) / total,
r,
r0,
colors[i]
);
}
html +=
'<circle cx="' +
r +
'" cy="' +
r +
'" r="' +
r0 +
'" fill="white" /><text dominant-baseline="central" transform="translate(' +
r +
', ' +
r +
')">' +
total.toLocaleString() +
'</text></svg></div>';
var el = document.createElement('div');
el.innerHTML = html;
return el.firstChild;
}
function donutSegment(start, end, r, r0, color) {
if (end - start === 1) end -= 0.00001;
var a0 = 2 * Math.PI * (start - 0.25);
var a1 = 2 * Math.PI * (end - 0.25);
var x0 = Math.cos(a0),
y0 = Math.sin(a0);
var x1 = Math.cos(a1),
y1 = Math.sin(a1);
var largeArc = end - start > 0.5 ? 1 : 0;
return [
'<path d="M',
r + r0 * x0,
r + r0 * y0,
'L',
r + r * x0,
r + r * y0,
'A',
r,
r,
0,
largeArc,
1,
r + r * x1,
r + r * y1,
'L',
r + r0 * x1,
r + r0 * y1,
'A',
r0,
r0,
0,
largeArc,
0,
r + r0 * x0,
r + r0 * y0,
'" fill="' + color + '" />'
].join(' ');
}
</script>
</body>
</html>