skmeans

Super fast simple k-means and k-means++ implementation for unidimiensional and multidimensional data. Works on nodejs and browser.

Installation

npm install skmeans

Usage

NodeJS

const skmeans = require("skmeans");

var data = [1,12,13,4,25,21,22,3,14,5,11,2,23,24,15];
var res = skmeans(data,3);

Browser

Results

{
	it: 2,
	k: 3,
	idxs: [ 2, 0, 0, 2, 1, 1, 1, 2, 0, 2, 0, 2, 1, 1, 0 ],
	centroids: [ 13, 23, 3 ]
}

API

skmeans(data,k,[centroids],[iterations])

Calculates unidimiensional and multidimensional k-means clustering on data. Parameters are:

• data Unidimiensional or multidimensional array of values to be clustered. for unidimiensional data, takes the form of a simple array [1,2,3.....,n]. For multidimensional data, takes a NxM array [[1,2],[2,3]....[n,m]]
• k Number of clusters
• centroids Optional. Initial centroid values. If not provided, the algorith will try to choose an apropiate ones. Alternative values can be:
  • "kmrand" Cluster initialization will be random, but with extra checking, so there will no be two equal initial centroids.
  • "kmpp" The algorythm will use the k-means++ cluster initialization method.
• iterations Optional. Maximum number of iterations. If not provided, it will be set to 10000.
• distance function Optional. Custom distance function. Takes two points as arguments and returns a scalar number.

The function will return an object with the following data:

• it The number of iterations performed until the algorithm has converged
• k The cluster size
• centroids The value for each centroid of the cluster
• idxs The index to the centroid corresponding to each value of the data array
• test Function to test new point membership

Examples

// k-means with 3 clusters. Random initialization
var res = skmeans(data,3);

// k-means with 3 clusters. Initial centroids provided
var res = skmeans(data,3,[1,5,9]);

// k-means with 3 clusters. k-means++ cluster initialization
var res = skmeans(data,3,"kmpp");

// k-means with 3 clusters. Random initialization. 10 max iterations
var res = skmeans(data,3,null,10);

// k-means with 3 clusters. Custom distance function
var res = skmeans(data,3,null,null,(x1,x2)=>Math.abs(x1-x2));

// Test new point
var res = skmeans(data,3,null,10);
res.test(6);

// Test new point with custom distance
var res = skmeans(data,3,null,10);
res.test(6,(x1,x2)=>Math.abs(x1-x2));