Kmeans.cpp

#include <math.h>

#include "KMeans.h"

KMeans::KMeans(int dimension_data, int number_clusters){
	this->dimension_data = dimension_data;
	this->number_clusters = number_clusters;

	centroid = new double*[number_clusters];

	for (int i = 0; i < number_clusters; i++){
		centroid[i] = new double[dimension_data];
	}
}
KMeans::~KMeans(){
	for (int i = 0; i < number_clusters; i++){
		delete[] centroid[i];
	}
	delete[] centroid;
}

void KMeans::Initialize(int number_data, double **data){
	for (int i = 0; i < number_clusters; i++){
		int number_sample = number_data / number_clusters;

		for (int j = 0; j < dimension_data; j++){
			double sum = 0;

			for (int k = i * number_sample; k < (i + 1) * number_sample; k++){
				sum += data[k][j];
			}
			centroid[i][j] = sum / number_sample;
		}
	}
}

int KMeans::Classify(double data[]){
	int argmin;

	double min = -1;

	for (int j = 0; j < number_clusters; j++){
		double distance = 0;

		for (int k = 0; k < dimension_data; k++){
			distance += (data[k] - centroid[j][k]) * (data[k] - centroid[j][k]);
		}
		distance = sqrt(distance);

		if (min == -1 || min > distance){
			argmin = j;
			min = distance;
		}
	}
	return argmin;
}

double KMeans::Cluster(int number_data, double **data){
	double movements_centroids = 0;

	int *label = new int[number_data];

	double *mean = new double[dimension_data];

	for (int i = 0; i < number_data; i++){
		label[i] = Classify(data[i]);
	}

	for (int j = 0; j < number_clusters; j++){
		int number_sample = 0;

		double movements = 0;

		for (int k = 0; k < dimension_data; k++){
			mean[k] = 0;
		}
		for (int i = 0; i < number_data; i++){
			if (label[i] == j){
				for (int k = 0; k < dimension_data; k++){
					mean[k] += data[i][k];
				}
				number_sample++;
			}
		}
		for (int k = 0; k < dimension_data; k++){
			if (number_sample) mean[k] /= number_sample;

			movements += (centroid[j][k] - mean[k]) * (centroid[j][k] - mean[k]);
			centroid[j][k] = mean[k];
		}
		movements_centroids += sqrt(movements);
	}
	delete[] label;
	delete[] mean;

	return movements_centroids;
}