supercluster

This repository is a fork of mapbox/supercluster, but for CGCS2000 projection.

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

<script src="https://unpkg.com/[email protected]/dist/supercluster.min.js"></script>

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

Clustering 6 million points in Leaflet:

Install

Install using NPM (npm install supercluster) or Yarn (yarn add supercluster), then:

// import as a ES module
import Supercluster from 'supercluster';

// or require in Node / Browserify
const Supercluster = require('supercluster');

Or use a browser build directly:

<script src="https://unpkg.com/[email protected]/dist/supercluster.min.js"></script>

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. | | minPoints | 2 | Minimum number of points to form a cluster. | | 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. | | generateId | false | Whether to generate ids for input features in vector tiles. |

Property map/reduce options

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

• map: a function that returns cluster properties corresponding to a single point.
• reduce: a reduce function that merges properties of two clusters into one.

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

const index = new Supercluster({
    map: (props) => ({sum: props.myValue}),
    reduce: (accumulated, props) => { accumulated.sum += props.sum; }
});

Note that reduce must not mutate the second argument (props).

Developing Supercluster

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