GitHub - mourner/kdbush: A fast static index for 2D points (original) (raw)

KDBush

A very fast static spatial index for 2D points based on a flat KD-tree. Compared to RBush:

• Points only — no rectangles.
• Static — you can't add/remove items after initial indexing.
• Faster indexing and search, with lower memory footprint.
• Index is stored as a single array buffer (so you can transfer it between threads or store it as a compact file).

If you need a static index for rectangles, not only points, see Flatbush. When indexing points, KDBush has the advantage of taking ~2x less memory than Flatbush.

Usage

// initialize KDBush for 1000 items const index = new KDBush(1000);

// fill it with 1000 points for (const {x, y} of items) { index.add(x, y); }

// perform the indexing index.finish();

// make a bounding box query const foundIds = index.range(minX, minY, maxX, maxY);

// map ids to original items const foundItems = foundIds.map(i => items[i]);

// make a radius query const neighborIds = index.within(x, y, 5);

// instantly transfer the index from a worker to the main thread postMessage(index.data, [index.data]);

// reconstruct the index from a raw array buffer const index = KDBush.from(e.data);

Install

Install with NPM: npm install kdbush, then import as a module:

import KDBush from 'kdbush';

Or use as a module directly in the browser with jsDelivr:

Alternatively, there's a browser bundle with a KDBush global variable:

API

new KDBush(numItems[, nodeSize, ArrayType])

Creates an index that will hold a given number of points (numItems). Additionally accepts:

• nodeSize: Size of the KD-tree node, 64 by default. Higher means faster indexing but slower search, and vise versa.
• ArrayType: Array type to use for storing coordinate values. Float64Array by default, but if your coordinates are integer values, Int32Array makes the index faster and smaller.

index.add(x, y)

Adds a given point to the index. Returns a zero-based, incremental number that represents the newly added point.

index.range(minX, minY, maxX, maxY)

Finds all items within the given bounding box and returns an array of indices that refer to the order the items were added (the values returned by index.add(x, y)).

index.within(x, y, radius)

Finds all items within a given radius from the query point and returns an array of indices.

KDBush.from(data)

Recreates a KDBush index from raw ArrayBuffer data (that's exposed as index.data on a previously indexed KDBush instance). Very useful for transferring or sharing indices between threads or storing them in a file.

Properties

• data: array buffer that holds the index.
• numItems: number of stored items.
• nodeSize: number of items in a KD-tree node.
• ArrayType: array type used for internal coordinates storage.
• IndexArrayType: array type used for internal item indices storage.