supercluster

A very fast JavaScript library for geospatial point clustering for browsers and Node.

<script src="https://unpkg.com/supercluster@2.3.0/dist/supercluster.min.js"></script>

var index = supercluster({
    radius: 40,
    maxZoom: 16
});
index.load(points);
index.getClusters([-180, -85, 180, 85], 2);

Clustering 6 million points in Leaflet:

Methods

load(points)

Loads an array of GeoJSON.Feature objects. Each feature's geometry must be a GeoJSON.Point. Once loaded, index is immutable.

getClusters(bbox, zoom)

For the given bbox array ([westLng, southLat, eastLng, northLat]) and integer zoom, returns an array of clusters and points as GeoJSON.Feature objects.

getTile(z, x, y)

For a given zoom and x/y coordinates, returns a geojson-vt-compatible JSON tile object with cluster/point features.

getChildren(clusterId)

Returns the children of a cluster (on the next zoom level) given its id (cluster_id value from feature properties).

getLeaves(clusterId, limit = 10, offset = 0)

Returns all the points of a cluster (given its cluster_id), with pagination support: limit is the number of points to return (set to Infinity for all points), and offset is the amount of points to skip (for pagination).

getClusterExpansionZoom(clusterId)

Returns the zoom on which the cluster expands into several children (useful for "click to zoom" feature) given the cluster's cluster_id.

Options

Option	Default	Description
minZoom	0	Minimum zoom level at which clusters are generated.
maxZoom	16	Maximum zoom level at which clusters are generated.
radius	40	Cluster radius, in pixels.
extent	512	(Tiles) Tile extent. Radius is calculated relative to this value.
nodeSize	64	Size of the KD-tree leaf node. Affects performance.
log	false	Whether timing info should be logged.

Property map/reduce options

In addition to the options above, supercluster supports property aggregation with the following three options:

• initial: a function that returns an object with cluster's initial properties.
• map: a function that returns properties to use for individual points.
• reduce: a reduce function for calculating properties in clusters.

Example of setting up a sum cluster property that accumulates the sum of myValue property values:

var index = supercluster({
    initial: function() { return {sum: 0}; },
    map: function(props) { return {sum: props.myValue}; },
    reduce: function(accumulated, props) { accumulated.sum += props.sum; }
});

Developing Supercluster

npm install       # install dependencies
npm run build-dev # generate dist/supercluster.js
npm run build-min # generate dist/supercluster.min.js
npm test          # run tests