programming-examples/java/Implementation of clustering algorithm K-means.java
2019-11-18 13:43:20 +01:00

139 lines
4.7 KiB
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("}");
}
}
}