Point-cluster NPM

point-cluster

Point clustering for 2D spatial indexing. Incorporates optimized quad-tree data structure.

const cluster = require('point-cluster')

let ids = cluster(points)

// get point ids in the indicated range
let selectedIds = ids.range([10, 10, 20, 20])

// get levels of details: list of ids subranges for rendering purposes
let lod = ids.range([10, 10, 20, 20], { lod: true })

API

`ids = cluster(points, options?)`

Create index for the set of 2d points based on options.

points is an array of [x,y, x,y, ...] or [[x,y], [x,y], ...] coordinates.
ids is Uint32Array with point ids sorted by zoom levels, suitable for WebGL buffer, subranging or alike.
options

Option	Default	Description
`bounds`	`'auto'`	Data range, if different from `points` bounds, eg. in case of subdata.
`depth`	`256`	Max number of levels. Points below the indicated level are grouped into single level.
`output`	`'array'`	Output data array or data format. For available formats see dtype.
<!-- `node`	`1`	Min size of node, ie. tree traversal is stopped once the node contains less than the indicated number of points. -->
<!-- `sort`	`'z'`	Sort values within levels by `x`-, `y`-coordinate, `z`-curve or `r` - point radius. `z` is the fastest for init, `x` or `y` are faster for `lod` and `r` is the most data-relevant. -->
<!-- `pick`	`'first'`	`'first'`, `'last'` or a function, returning point id for the level. -->

`result = ids.range(box?, options?)`

Get point ids from the indicated range.

box can be any rectangle object, eg. [l, t, r, b], see parse-rect.
options

Option	Default	Description
`lod`	`false`	Makes result a list of level details instead of ids, useful for obtaining subranges to render.
`px`	`0`	Min pixel size in data dimension (number or `[width, height]` couple) to search for, to ignore lower levels.
`level`	`null`	Max level to limit search.

let levels = ids.range([0,0, 100, 100], { lod: true, d: dataRange / canvas.width })

levels.forEach([from, to] => {
	// offset and count point to range in `ids` array
	render( ids.subarray( from, to ) )
})