119 lines
3.8 KiB
JavaScript
119 lines
3.8 KiB
JavaScript
// Original is by Nathan Epstein and found at https://github.com/NathanEpstein/clusters/blob/master/clusters.js
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// Modified for browser
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var Cluster = {
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data: getterSetter([], function(arrayOfArrays) {
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if(!arrayOfArrays[0]){
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arrayOfArrays[0]=[0,0]
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}
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var n = arrayOfArrays[0].length;
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return (arrayOfArrays.map(function(array) {
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return array.length == n;
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}).reduce(function(boolA, boolB) { return (boolA & boolB) }, true));
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}),
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clusters: function() {
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var pointsAndCentroids = kmeans(this.data(), {k: this.k(), iterations: this.iterations() });
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var points = pointsAndCentroids.points;
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var centroids = pointsAndCentroids.centroids;
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return centroids.map(function(centroid) {
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return {
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centroid: centroid.location(),
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points: points.filter(function(point) { return point.label() == centroid.label() }).map(function(point) { return point.location() }),
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};
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});
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},
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k: getterSetter(undefined, function(value) { return ((value % 1 == 0) & (value > 0)) }),
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iterations: getterSetter(Math.pow(10, 3), function(value) { return ((value % 1 == 0) & (value > 0)) }),
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};
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function kmeans(data, config) {
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// default k
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var k = config.k || Math.round(Math.sqrt(data.length / 2));
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var iterations = config.iterations;
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// initialize point objects with data
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var points = data.map(function(vector) { return new Point(vector) });
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// intialize centroids randomly
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var centroids = [];
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for (var i = 0; i < k; i++) {
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centroids.push(new Centroid(points[i % points.length].location(), i));
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};
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// update labels and centroid locations until convergence
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for (var iter = 0; iter < iterations; iter++) {
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points.forEach(function(point) { point.updateLabel(centroids) });
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centroids.forEach(function(centroid) { centroid.updateLocation(points) });
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};
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// return points and centroids
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return {
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points: points,
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centroids: centroids
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};
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};
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// objects
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function Point(location) {
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var self = this;
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this.location = getterSetter(location);
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this.label = getterSetter();
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this.updateLabel = function(centroids) {
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var distancesSquared = centroids.map(function(centroid) {
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return sumOfSquareDiffs(self.location(), centroid.location());
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});
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self.label(mindex(distancesSquared));
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};
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};
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function Centroid(initialLocation, label) {
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var self = this;
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this.location = getterSetter(initialLocation);
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this.label = getterSetter(label);
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this.updateLocation = function(points) {
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var pointsWithThisCentroid = points.filter(function(point) { return point.label() == self.label() });
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if (pointsWithThisCentroid.length > 0) self.location(averageLocation(pointsWithThisCentroid));
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};
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};
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// convenience functions
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function getterSetter(initialValue, validator) {
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var thingToGetSet = initialValue;
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var isValid = validator || function(val) { return true };
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return function(newValue) {
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if (typeof newValue === 'undefined') return thingToGetSet;
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if (isValid(newValue)) thingToGetSet = newValue;
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};
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};
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function sumOfSquareDiffs(oneVector, anotherVector) {
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var squareDiffs = oneVector.map(function(component, i) {
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return Math.pow(component - anotherVector[i], 2);
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});
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return squareDiffs.reduce(function(a, b) { return a + b }, 0);
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};
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function mindex(array) {
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var min = array.reduce(function(a, b) {
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return Math.min(a, b);
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});
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return array.indexOf(min);
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};
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function sumVectors(a, b) {
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return a.map(function(val, i) { return val + b[i] });
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};
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function averageLocation(points) {
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var zeroVector = points[0].location().map(function() { return 0 });
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var locations = points.map(function(point) { return point.location() });
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var vectorSum = locations.reduce(function(a, b) { return sumVectors(a, b) }, zeroVector);
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return vectorSum.map(function(val) { return val / points.length });
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}; |