kmean.java

import java.util.*;

public class kmean {
    
    public static void main(String[] args) {
        
        int[] dataset = { 2,3,4,10,11,12,20,25,30 };
        
        ArrayList<Integer> c1 = new ArrayList<Integer>();
        ArrayList<Integer> c2 = new ArrayList<Integer>();

        
        cluster(dataset,4,12,c1,c2);


        System.out.println("C1");
        
        for(int j=0; j<c1.size();j++) {
            System.out.println(c1.get(j));
        }
        
        System.out.println("C2");
        
        for(int j=0; j<c2.size();j++) {
            System.out.println(c2.get(j));
        }

    }


    public static void cluster(int[]dataset,int m1,int m2,ArrayList<Integer> c1,ArrayList<Integer> c2) {
        
        c1.clear();
        c2.clear();

        int i = 0;
        while(i<dataset.length) {

            if(dataset[i]<=m1) {

                c1.add(dataset[i]);

            } else if(dataset[i]>=m2) {

                c2.add(dataset[i]);

            } else if( Math.abs(m1-dataset[i]) > Math.abs(m2-dataset[i]) ) {

                c2.add(dataset[i]);

            } else {
                c1.add(dataset[i]);
            }
            i++;
        }

        if( m1!=mean1(c1) && m2!=mean2(c2) ) {
            
            
            m1 = mean1(c1);
            m2 = mean2(c2);

            cluster(dataset, m1, m2,c1,c2);
        }

    }

    public static int mean1(ArrayList<Integer> c1) {
        
        int sum = 0;
        for(int j=0; j<c1.size();j++) {
            sum = sum + c1.get(j);
        }
        
        return sum/c1.size();

    }

    public static int mean2(ArrayList<Integer> c2) {
        
        int sum = 0;
        for(int j=0; j<c2.size();j++) {
            sum = sum + c2.get(j);
        }

        return sum/c2.size();

    }

}