Parallel Counter Sort

[flyntcoal]

First of all, let me explain that counter sort is an optimized version of counting sort. Counter sort takes the highest and lowest values and then makes an array from the lowest to the highest and counts the number of times that the index of the counter array in in the sorting array. Then it creates a new array by placing the index from the counter array back in sorted order.

Right now when I run the current code I have I get an exception:
Exception in thread "Thread-1" java.lang.ArrayIndexOutOfBoundsException: 10
at ParCountSor.Thread1.run(Thread1.java:48)

So, somehow I am reach outside of my array or not stopping. I'm looking through it and could use some fresh eyes to help me figure out where I am going wrong with my sort and how I'm going through the array.

package ParCountSor;

import java.util.Random;
import java.util.Scanner;

public class CountSort {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int i, j = 0;
		int counter = 0;//test for how many times it runs.
        int[] data;
        Random ranGen = new Random();
        //Accept in the Command Line Parameter
        //If the parameter is correct.
       if(args.length == 2){
               int testnum = Integer.parseInt(args[1]);//how many times it will run
       for (i = 0; i != testnum; i++){
                int[] ranarray = new int [10];//random array to be sorted
                int arraynumb = i;//just to tell what array is being sorted
                	arraynumb++;//make the number more real
                
                System.out.println("For array " + arraynumb);
                    for (j = 0; j < ranarray.length; j++){
                    	int ran = ranGen.nextInt(301); //Randomly generates number (0 - 19)
                         System.out.print(" " + ran);
                         ranarray[j] = ran; //Random number added
                         data = ranarray;

                    }//for
                    System.out.println("");
                    Thread1 t1 = new Thread1(ranarray);//pass over to the thread
            		t1.start();//start the thread

            		try {
            			t1.join();//bring back the values from thread 1
            		} catch (InterruptedException e) {
            			// TODO Auto-generated catch block
            			e.printStackTrace();
            		}
                counter++; //Counter + 1
       }//for

        System.out.println("\nSorted " +  counter + " time(s)");
        //Print out how many successful times it sorted
        }else if(args.length > 2 ) {
          System.out.println("Too many arguments supplied.");
        }
        //else too few arguments
        else{
          System.out.println("One argument expected.");
        }	
	}

}

Thread1 class

package ParCountSor;

	public class Thread1 extends Thread{
		private static int[] result;
		public int[] cArray;//half of array to search
		public Thread1(int[] ranarray) {
			//constructor for firstHalf and target
			this.cArray = ranarray;//copy array
		}
		
		public int findmax(){
			int max = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] > max){
					max = cArray[i];
				}
			}
			return max;
		}
		
		public int findmin(){
			int min = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] < min){
					min = cArray[i];
				}
			}
			return min;
		}

		public void run(){
			int max = findmax();
			int min = findmin();
			int range = max - min +1;
			int [] counts = new int[range];
			result = new int [cArray.length];
			for(int i = 0; i < cArray.length; i++){
				//counts[cArray[i]] = counts[cArray[i]]++;
				counts[cArray[i]- min]++;
			}
			
			for(int i = 1; i < counts.length; i++){
				counts[i] = counts[i] + counts[i-1];
			}
			
			for(int i = cArray.length - 1; i >= 0; i--){
				//counts[cArray[i]]++;
				result[counts[cArray[i] - min]--] = cArray[i];
			}
			
		}//end run method
		
		/*public void setResult(int result){
			this.result = result;
		}*/
		public int[] getResult(){
			return this.result;
		}
		
	}//end Thread1 class

Also posted:
http://www.dreamincode.net/forums/to...-counter-sort/

[flyntcoal]

Yea I fixed those comments and added. (I do all that last, focus on making code work first, then fix comments).

So I went back through and just redid a lot of my code finding a different model to follow, and it compiles and runs. Just bad output. Here is what I got last time.

For array 1
286 182 52 284 137 157 18 3 299 147
Sorted Array:
12 182 52 284 137 157 18 3 299 147

Sorted 1 time(s)

The 286 was replaced with 12. And then the rest of the array is just printed without any changes. So seems like it passes thru, doesn't sort, replace the first, and prints that out.

CounterSort Class (Hasn't changed much)

package ParCountSor;

import java.util.Random;
import java.util.Scanner;

public class CountSort {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int i, j = 0;
		int counter = 0;//test for how many times it runs.
        int[] data;
        Random ranGen = new Random();
        //Accept in the Command Line Parameter
        //If the parameter is correct.
       if(args.length == 2){
               int testnum = Integer.parseInt(args[1]);//how many times it will run
       for (i = 0; i != testnum; i++){
                int[] ranarray = new int [10];//random array to be sorted
                int arraynumb = i;//just to tell what array is being sorted
                	arraynumb++;//make the number more real
                
                System.out.println("For array " + arraynumb);
                    for (j = 0; j < ranarray.length; j++){
                    	int ran = ranGen.nextInt(301); //Randomly generates number (0 - 300)
                         System.out.print(ran + " ");
                         ranarray[j] = ran; //Random number added
                         data = ranarray;

                    }//for
                    System.out.println("");
                    Thread1 t1 = new Thread1(ranarray);//pass over to the thread
            		t1.start();//start the thread

            		try {
            			t1.join();//bring back the values from thread 1
            		} catch (InterruptedException e) {
            			// TODO Auto-generated catch block
            			e.printStackTrace();
            		}
                counter++; //Counter + 1
       }//for

        System.out.println("\nSorted " +  counter + " time(s)");
        //Print out how many successful times it sorted
        }else if(args.length > 2 ) {
          System.out.println("Too many arguments supplied.");
        }
        //else too few arguments
        else{
          System.out.println("One argument expected.");
        }	
	}

}

Thread1 Class (Good deal of change)

package ParCountSor;

	public class Thread1 extends Thread{
		private int[] counts;
		public int[] cArray;//half of array to search
		public Thread1(int[] ranarray) {
			//constructor for firstHalf and target
			this.cArray = ranarray;//copy array
		}
		
		public int findmax(){
			int max = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] > max){
					max = cArray[i];
				}
			}
			return max;
		}
		
		public int findmin(){
			int min = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] < min){
					min = cArray[i];
				}
			}
			return min;
		}

		public void run(){
			int max = findmax();//max value
			int min = findmin();//min value
			int range = max - min +1;//find the range
			counts = new int[range];//counts array
			
			//make count of how many times it appears in the array
			for(int i = 0; i < cArray.length; i++){
				counts[cArray[i]- min]++;
			}//end for
			//make sure of positions in final array
			for(int i = 1; i < counts.length; i++){
				counts[i] += counts[i-1];
			}//end for
			//sort original array
			int j = 0;
			for(int i = cArray.length - 1; i >= 0; i--){
				while(j < counts[i]){
					cArray[j++] = i + min;
				}//end while
			}//end for
			//print sorted array
			System.out.println("Sorted Array: ");
			for(int i = 0; i < cArray.length; i++){
				System.out.print(cArray[i]+" ");
			}//end for
			System.out.println("");
		}//end run method

		public int[] getCounts(){
			return this.counts;
		}//end getResult
		
	}//end Thread1 class

[flyntcoal]

So, working through commented out code, a section, so I know where it was changing the first value, but still doesn't want to sort the data. So question is what is wrong with my sort?

			//sort original array
			int j = 0;
			for(int i = 0; i < counts.length; i++){
				while(j < counts[i]){
					cArray[j++] = i + minVal;
					counts[i]--;
				}//end while

Rest of my code Thread1 class code (the CountSort hasn't changed since above)

package ParCountSor;

	public class Thread1 extends Thread{
		private int[] counts;
		public int[] cArray;//half of array to search
		public Thread1(int[] ranarray) {
			//constructor for firstHalf and target
			this.cArray = ranarray;//copy array
		}
		
		public int findmax(){
			int max = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] > max){
					max = cArray[i];
				}
			}
			return max;
		}
		
		public int findmin(){
			int min = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] < min){
					min = cArray[i];
				}
			}
			return min;
		}

		public void run(){
			int maxVal = findmax();//max value
			int minVal = findmin();//min value
			int range = maxVal - minVal +1;//find the range
			counts = new int[range];//counts array
			
			//make count of how many times it appears in the array
			/*for(int i = 0; i < cArray.length; i++){
				counts[cArray[i]- min]++;
			}//end for*/
			for(int i =0; i < cArray.length; i++){
				counts[cArray[i] - minVal]++;
			}
			/*//make sure of positions in final array
			for(int i = 1; i < counts.length; i++){
				counts[i] += counts[i-1];
			}//end for*/
			//sort original array
			int j = 0;
			for(int i = 0; i < counts.length; i++){
				while(j < counts[i]){
					cArray[j++] = i + minVal;
					counts[i]--;
				}//end while
			}//end for
			//print sorted array
			System.out.println("Sorted Array: ");
			for(int i = 0; i < cArray.length; i++){
				System.out.print(cArray[i]+" ");
			}//end for
			System.out.println("");
		}//end run method

		public int[] getCounts(){
			return this.counts;
		}//end getResult
		
	}//end Thread1 class

[2kaud]

What debugging of the code has been done? Has the code been traced to see what happens when that code is executed to determine when/why it deviates from what is expected?

[flyntcoal]

i've run test prints, commenting out code, i've went thru it with the debugger and it runs thru, but doesn't sort the data the way i'm need it to. i'm not sure how fair off i am because i've been looking at counting sorts (less optimized version of counter sort) and what i have is either the same or they have a few lines different from mine.

[2kaud]

i've went thru it with the debugger and it runs thru, but doesn't sort the data the way i'm need it to

In that case, tracing through the code execution with the debugger should show why the data is not being sorted properly as you'll be able to see the variable contents and the path taken through the code.

[flyntcoal]

So mainly been cleaning up my code and testing. When I now run this, I get this as the result.

For array 1
261 155 13 31 203 298 13 122 237 173
Exception in thread "Thread-0" java.lang.ArrayIndexOutOfBoundsException: 286
at ParCountSor.Thread1.run(Thread1.java:46)

Sorted 1 time(s)

That 286 is the range variable that is the length of the counts array. Completely confused there. Does it think that I want the value to be 286? Am I set the size of the counts array wrong?

Thread1 (CountSort class hasn't changed)

package ParCountSor;

import java.util.Arrays;

	public class Thread1 extends Thread{
		private int[] counts;
		public int[] cArray;//half of array to search
		public Thread1(int[] ranarray) {
			//constructor for firstHalf and target
			this.cArray = ranarray;//copy array
		}
		
		public int findmax(){
			int max = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] > max){
					max = cArray[i];
				}
			}
			return max;
		}
		
		public int findmin(){
			int min = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] < min){
					min = cArray[i];
				}
			}
			return min;
		}

		public void run(){
			int maxVal = findmax();//max value
			int minVal = findmin();//min value
			int range = maxVal - minVal +1;//find the range
			counts = new int[range];//counts array
			

			for(int i =0; i < cArray.length; i++){
				counts[cArray[i]-minVal]++;
			}
			int j = 0;
			for(int i = 0; i < counts.length; i++){
				while(counts[i] > 0){
					counts[j++] = i + minVal;
					counts[i]--;
				}
			}
			//print sorted array
			System.out.println("Sorted Array: " + Arrays.toString(counts));
			
			System.out.println("");
		}//end run method

		public int[] getCounts(){
			return this.counts;
		}//end getResult
		
	}//end Thread1 class

[flyntcoal]

GOT IT! Finally got it to sort and everything. I would say the only thing it does wrong is it takes the last value of the original array and then prints that at the end. For example:

268 31 218 114 55 73 213 276 211 195
Sorted Array: [31, 55, 73, 114, 195, 211, 213, 218, 268, 195]


Sorted 1 time(s)

That 195 is just reprinted, there are not another 195 in the array. So if I could get help one last few things. Why is that last value there, and if anyone can double check my comments to make sure they make sense, that would be amazing!

Thank you!

My code:

package ParCountSor;

import java.util.Random;


public class CountSort {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		int i, j = 0;
		int counter = 0;//test for how many times it runs.
        int[] data = new int [10];
        Random ranGen = new Random();
        //Accept in the Command Line Parameter
        //If the parameter is correct.
       if(args.length == 2){
               int testnum = Integer.parseInt(args[1]);//how many times it will run
       for (i = 0; i != testnum; i++){
                int[] ranarray = new int [10];//random array to be sorted
                int arraynumb = i;//just to tell what array is being sorted
                	arraynumb++;//make the number more real
                
                System.out.println("For array " + arraynumb);
                    for (j = 0; j < ranarray.length; j++){
                    	int ran = ranGen.nextInt(301); //Randomly generates number (0 - 300)
                         System.out.print(ran + " ");
                         ranarray[j] = ran; //Random number added
                         data = ranarray;

                    }//for
                    System.out.println("");
                    Thread1 t1 = new Thread1(data);//pass over to the thread
            		t1.start();//start the thread

            		try {
            			t1.join();//bring back the values from thread 1
            		} catch (InterruptedException e) {
            			// TODO Auto-generated catch block
            			e.printStackTrace();
            		}
                counter++; //Counter + 1
       }//for

        System.out.println("\nSorted " +  counter + " time(s)");
        //Print out how many successful times it sorted
        }else if(args.length > 2 ) {
          System.out.println("Too many arguments supplied.");
        }
        //else too few arguments
        else{
          System.out.println("One argument expected.");
        }	
	}

}

Thread1 class

package ParCountSor;

import java.util.Arrays;

	public class Thread1 extends Thread{
		private int[] counts;
		public int[] cArray;//half of array to search
		public Thread1(int[] data) {
			//constructor for firstHalf and target
			this.cArray = data;//copy array
		}	
		//find the max value in the array
		public int findmax(){
			int max = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] > max){
					max = cArray[i];
				}
			}
			return max;
		}
		//find the minimum value in the array
		public int findmin(){
			int min = cArray[0];
			for(int i = 0; i < cArray.length; i++){
				if (cArray[i] < min){
					min = cArray[i];
				}
			}
			return min;
		}
		
		//run method executes the counter sort
		public void run(){
			int maxVal = findmax();//max value
			int minVal = findmin();//min value
			int range = maxVal - minVal + 1;//find the range
			int[] counts = new int[range];//counts array
			//counts the number of frequencies of each value of the array
			for(int i =0; i < cArray.length; i++){
				counts[cArray[i] - minVal]++;
			}
			//data in cArray is sorted from lower to highest based on counts array
			int j = 0;
			for(int i = minVal; i < maxVal; i++){
				while(counts[i - minVal] > 0){
					cArray[j] = i;
					j++;
					counts[i - minVal]--;
				}
			}//end for
			//print sorted array
			System.out.println("Sorted Array: " + Arrays.toString(cArray));
		}//end run method

		public int[] getCounts(){
			return this.counts;
		}//end getResult
		
	}//end Thread1 class

[2kaud]

That 195 is just reprinted,

No. 276 in the input isn't in the output. It should be on the end where the duplicated 195 is.