Quick KMeans hack for Node-RED

kmeans.js

function initCentroids(pts, k) {
  var randPts = pts.slice(0);
  randPts.sort(() => Math.floor(Math.random() * pts.length));
  return randPts.slice(0, k);
}

function dist(v1, v2) {
  var sum = 0;
  for (var i = 0; i < v1.length; i++) {
    if (i !== 0) sum += Math.pow(v2[i] - v1[i], 2);
  }
  return Math.sqrt(sum);
}

function findNearestCentroid(pt, cents) {
  var minDist = Infinity,
    idx = 0;

  for (var i = 0; i < cents.length; i++) {
    var d = dist(pt, cents[i]);
    if (d < minDist) {
      minDist = d;
      idx = i;
    }
  }
  return idx;
}

function iterate(pts, k, cents) {
  var clusters = new Array(k);
  var zeros = [];
  for (var i = 0; i < pts[0].length; i++) {
    zeros.push(0);
  }
  var sums = [];
  for (var i = 0; i < k; i++) {
    sums[i] = zeros.slice(0);
  }

  var clusterIds = new Array(pts.length);

  for (var i = 0; i < pts.length; i++) {
    var pt = pts[i].slice(0);
    var clusterId = findNearestCentroid(pt, cents);

    clusterIds[i] = clusterId;

    if (!clusters[clusterId]) clusters[clusterId] = [];
    clusters[clusterId].push(pt);

    for (var j = 0; j < pt.length; j++) {
      sums[clusterId][j] += pt[j];
    }
  }

  var maxDist = 0;

  for (var i = 0; i < k; i++) {
    var size = clusters[i] ? clusters[i].length : 0;

    for (var j = 0; j < sums[i].length; j++) {
      sums[i][j] = sums[i][j] / size;
    }
    var centDist = dist(sums[i], cents[i]);
    if (centDist > maxDist) maxDist = centDist;
  }

  if (maxDist <= 0.5) {
    return clusterIds;
  }

  for (var i = 0; i < k; i++) {
    cents[i] = sums[i].slice(0);
  }
  return iterate(pts, k, cents);
}

function kmeans(pts, k) {
  if (!pts || !k) {
    throw new Error("Provide 2 arguments: points and clusters");
  }

  if (!pts.length || !pts[0].length) {
    throw new Error("Points array cannot be empty");
  }

  if (k < 1 || k > pts.length) {
    throw new Error("K must be between 1 and the number of points");
  }

  var cents = initCentroids(pts, k);
  return iterate(pts, k, cents);
}

try {
  var clusterIds = kmeans(msg.payload, msg.clusters || 4);
  msg = {
    payload: clusterIds,
  };
  return msg;
} catch (error) {
  console.error(error);
  return null;
}