k_means.java

import java.util.*;
class k_means
{
    static int count1,count2,count3;
    static int d[];
    static int k[][];
    static int tempk[][];
    static double m[];
    static double diff[];
    static int n,p;
    
    static int cal_diff(int a) // This method will determine the cluster in which an element go at a particular step.
    {
        int temp1=0;
        for(int i=0;i<p;++i)
        {
            if(a>m[i])
            diff[i]=a-m[i];
            else
                diff[i]=m[i]-a;
        }
        int val=0;
        double temp=diff[0];
        for(int i=0;i<p;++i)
        {
            if(diff[i]<temp)
            {
                temp=diff[i];
                val=i;
            }
        }//end of for loop
        return val;
    }
    
    static void cal_mean() // This method will determine intermediate mean values
    {
        for(int i=0;i<p;++i)
        m[i]=0; // initializing means to 0
        int cnt=0;
        for(int i=0;i<p;++i)
        {
            cnt=0;
            for(int j=0;j<n-1;++j)
            {
                if(k[i][j]!=-1)
                {
                    m[i]+=k[i][j];
                    ++cnt;
                }}
                m[i]=m[i]/cnt;
            }
        }
        
        static int check1() // This checks if previous k ie. tempk and current k are same.Used as terminating case.
        {
            for(int i=0;i<p;++i)
            for(int j=0;j<n;++j)
            if(tempk[i][j]!=k[i][j])
            {
                return 0;
            }
            return 1;
        }
        
        public static void main(String args[])
        {
            Scanner scr=new Scanner(System.in);
            /* Accepting number of elements */
            System.out.println("Enter the number of elements ");
            n=scr.nextInt();
            d=new int[n];
            /* Accepting elements */
            System.out.println("Enter "+n+" elements: ");
            for(int i=0;i<n;++i)
            d[i]=scr.nextInt();
            /* Accepting num of clusters */
            System.out.println("Enter the number of clusters: ");
            p=scr.nextInt();
            /* Initialising arrays */
            k=new int[p][n];
            tempk=new int[p][n];
            m=new double[p];
            diff=new double[p];
            /* Initializing m */
            for(int i=0;i<p;++i)
            m[i]=d[i];
            
            int temp=0;
            int flag=0;
            do
            {
                for(int i=0;i<p;++i)
                for(int j=0;j<n;++j)
                {
                    k[i][j]=-1;
                }
                for(int i=0;i<n;++i) // for loop will cal cal_diff(int) for every element.
                {
                    temp=cal_diff(d[i]);
                    if(temp==0)
                    k[temp][count1++]=d[i];
                    else
                        if(temp==1)
                    k[temp][count2++]=d[i];
                    else
                        if(temp==2)
                    k[temp][count3++]=d[i];
                }
                cal_mean(); // call to method which will calculate mean at this step.
                flag=check1(); // check if terminating condition is satisfied.
                if(flag!=1)
                /*Take backup of k in tempk so that you can check for equivalence in next step*/
                for(int i=0;i<p;++i)
                for(int j=0;j<n;++j)
                tempk[i][j]=k[i][j];
                
                System.out.println("\n\nAt this step");
                System.out.println("\nValue of clusters");
                for(int i=0;i<p;++i)
                {
                    System.out.print("K"+(i+1)+"{ ");
                        for(int j=0;k[i][j]!=-1 && j<n-1;++j)
                        System.out.print(k[i][j]+" ");
                    System.out.println("}");
                }//end of for loop
                System.out.println("\nValue of m ");
                for(int i=0;i<p;++i)
                System.out.print("m"+(i+1)+"="+m[i]+"  ");
                
                count1=0;count2=0;count3=0;
            }
            while(flag==0);
            
            System.out.println("\n\n\nThe Final Clusters By Kmeans are as follows: ");
            for(int i=0;i<p;++i)
            {
                System.out.print("K"+(i+1)+"{ ");
                    for(int j=0;k[i][j]!=-1 && j<n-1;++j)
                    System.out.print(k[i][j]+" ");
                System.out.println("}");
            }
        }
    }