kmeans?

gistfile1.js

var sample = [
  [0,1],
  [0,2],
  [0,3],
  [3,8],
  [3,9],
  [4,8],
  [4,10],

  [3,1],
  [5,3],
  [6,7],
  [8,3],
  [3,4],
  [6,3],
  [1,10],
  [9,3],
  [4,7],
  [6,3],
  [2,5],
  [7,9]
]

var k_values = [
  [2,1],
  [5,4]
]


var old_ks = k_values;
var new_ks = kMeans(old_ks, sample);
var inn = 0;

// can't do recursive cause will hit stack limit
while (!equalKs(old_ks, new_ks)) {
  console.log("ks: ", old_ks ,"--", new_ks);
  old_ks = new_ks;
  new_ks = kMeans(new_ks, sample);
  
  // just in case
  inn += 1;
  if (inn > 1000) break;
}

console.log("final: ", new_ks);


// functions

function equalKs(k1, k2) {
  var res = true;

  k1.forEach(function(vec,i) {
    vec.forEach(function(v,_i) {
      if (k1[i][_i] !== k2[i][_i]) res = false;
    });
  });

  return res;
}

function kMeans(ks, vectors) {
  var clusters = [];
  ks.forEach(function() { clusters.push([])})

  vectors.forEach(function(v,i) {
    var index = closestTo(v, ks);
    clusters[index].push(v)
  });

  var new_ks = [];

  ks.forEach(function(v,i) {
    new_ks.push(geometricCenter(clusters[i]));
  });

  return new_ks;
}

function closestTo(vec, ks) {
  var k_distances = [];
  ks.forEach(function(v,i) {
    k_distances.push(sumOfSquares(vec,v));
  });

  return k_distances.indexOf(Math.min.apply(Math, k_distances));
}

function geometricCenter(vs) {
  var sums = [];

  vs[0].forEach(function(v,i) {
    var sum = 0;
    vs.forEach(function(_v,_i) {
      sum += vs[_i][i];
    });
    sums.push(sum);
  });

  var vec = [];

  sums.forEach(function(v,i) {
    var res = Math.round((v/vs.length)*1000)/1000
    vec.push(res);
  });
  return vec;
}

function sumOfSquares(v1, v2) {
  var sum = 0;

  v1.forEach(function(v,i) {
    sum += (v2[i] - v1[i])*(v2[i] - v1[i]);
  })

  return sum;
}