Visualize population density
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" /><script src="https://cdn.ndrive.com/nmapsgl/v.1.6.8/nmaps-gl.js"></script><link href="https://cdn.ndrive.com/nmapsgl/v.1.6.8/nmaps-gl.css" rel="stylesheet" /><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 nmapsgl.accessToken = '<your access token here>'; const map = new nmapsgl.Map({container: 'map', // container idstyle: 'Streets', // stylesheet locationcenter: [30.0222, -1.9596], // starting position [lng, lat]zoom: 7 // starting zoom}); map.on('load', () => {map.addSource('rwanda-provinces', {'type': 'geojson','data': 'https://nmaps-gl.ndrive.com/nmaps-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', '#edf8e9'],1551,['to-color', '#006d2c']],10,['interpolate',['linear'],['var', 'density'],274,['to-color', '#eff3ff'],1551,['to-color', '#08519c']]]],'fill-opacity': 0.7}});});</script> </body></html>