Visualize population density | Mapbox GL JS

Use a variable binding expression to calculate and display population density.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Visualize population density</title>
<meta name="viewport" content="initial-scale=1,maximum-scale=1,user-scalable=no">
<link href="https://api.mapbox.com/mapbox-gl-js/v3.3.0/mapbox-gl.css" rel="stylesheet">
<script src="https://api.mapbox.com/mapbox-gl-js/v3.3.0/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_MAPBOX_ACCESS_TOKEN';
    const map = new mapboxgl.Map({
        container: 'map', // container ID
        // Choose from Mapbox's core styles, or make your own style with Mapbox Studio
        style: 'mapbox://styles/mapbox/streets-v12', // style URL
        center: [30.0222, -1.9596], // starting position [lng, lat]
        zoom: 7 // starting zoom
    });

    map.on('load', () => {
        map.addSource('rwanda-provinces', {
            'type': 'geojson',
            'data': 'https://docs.mapbox.com/mapbox-gl-js/assets/rwanda-provinces.geojson'
        });
        map.addLayer(
            {
                'id': 'rwanda-provinces',
                'type': 'fill',
                'source': 'rwanda-provinces',
                'layout': {},
                'paint': {
                    'fill-color': [
                        'let',
                        'density',
                        ['/', ['get', 'population'], ['get', 'sq-km']],
                        [
                            'interpolate',
                            ['linear'],
                            ['zoom'],
                            8,
                            [
                                'interpolate',
                                ['linear'],
                                ['var', 'density'],
                                274,
                                ['to-color', '#f5e5f3'],
                                1551,
                                ['to-color', '#8d00ac']
                            ],
                            10,
                            [
                                'interpolate',
                                ['linear'],
                                ['var', 'density'],
                                274,
                                ['to-color', '#eff3ff'],
                                1551,
                                ['to-color', '#08519c']
                            ]
                        ]
                    ],
                    'fill-opacity': 0.7
                }
            },
            'road-label' // Place polygons under labels
        );
    });
</script>

</body>
</html>
Was this example helpful?