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Clustered Features

Example of using ol/source/Cluster.

This example shows how to do clustering on point features.

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index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Clustered Features</title>
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <form>
      <label>cluster distance</label>
      <input id="distance" type="range" min="0" max="100" step="1" value="40"/>
    </form>
    <script src="index.js"></script>
  </body>
</html>
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index.jsimport 'ol/ol.css';
import Feature from 'ol/Feature';
import Map from 'ol/Map';
import View from 'ol/View';
import Point from 'ol/geom/Point';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer';
import {Cluster, OSM, Vector as VectorSource} from 'ol/source';
import {Circle as CircleStyle, Fill, Stroke, Style, Text} from 'ol/style';


var distance = document.getElementById('distance');

var count = 20000;
var features = new Array(count);
var e = 4500000;
for (var i = 0; i < count; ++i) {
  var coordinates = [2 * e * Math.random() - e, 2 * e * Math.random() - e];
  features[i] = new Feature(new Point(coordinates));
}

var source = new VectorSource({
  features: features
});

var clusterSource = new Cluster({
  distance: parseInt(distance.value, 10),
  source: source
});

var styleCache = {};
var clusters = new VectorLayer({
  source: clusterSource,
  style: function(feature) {
    var size = feature.get('features').length;
    var style = styleCache[size];
    if (!style) {
      style = new Style({
        image: new CircleStyle({
          radius: 10,
          stroke: new Stroke({
            color: '#fff'
          }),
          fill: new Fill({
            color: '#3399CC'
          })
        }),
        text: new Text({
          text: size.toString(),
          fill: new Fill({
            color: '#fff'
          })
        })
      });
      styleCache[size] = style;
    }
    return style;
  }
});

var raster = new TileLayer({
  source: new OSM()
});

var map = new Map({
  layers: [raster, clusters],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 2
  })
});

distance.addEventListener('input', function() {
  clusterSource.setDistance(parseInt(distance.value, 10));
});
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package.json{
  "name": "cluster",
  "dependencies": {
    "ol": "6.1.1"
  },
  "devDependencies": {
    "parcel": "1.11.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --experimental-scope-hoisting --public-url . index.html"
  }
}