/*
 * Author: Aditya mathur.
 * Original: September 10, 2008
 * Revised; September 14, 2008. [Added some code as this was incomplete.]
 * 
 * This program illustrates the use of arrays in computing histograms.
 * Histogram categories are defined, data is generated randomly, histogram is computed and displayed.
 * 
 */
import java.lang.Double;
import java.util.Random;

public class Histogram{
    public static final int CATEGORIES=5;    
    private double [] boundaries;    
    private int [] histogram;    
    
    public Histogram()
    {    	
    	setCategories();
    	histogram = new int[CATEGORIES];
    }
    
    
    private void setCategories(){
      
      // Histogram Categories: A: <1 B: 1-3, C: 4-6, D: 7-9, E: >9
      boundaries = new double[CATEGORIES + 1];      
      boundaries[0]=Double.NEGATIVE_INFINITY;
      boundaries[1]=1;
      boundaries[2]=4;
      boundaries[3]=7;
      boundaries[4]=10;
      boundaries[5]=Double.POSITIVE_INFINITY;
    }
    
    public void compute(double [] data){
            
      for (int i=0; i<CATEGORIES; i++) // Initialize the counts.
        histogram[i]=0;
      
      for (int i=0; i<data.length; i++){  // Compute histogram
        for (int j=0; j<CATEGORIES; j++){
          if(data[i]>=boundaries[j] && data[i]<boundaries[j + 1]) histogram[j]++;
        }
      }
    }
    
// Display histogram. Math.rint(r.getPosX()*100.0d)/100.0d
    public void display(){      
      int count;
      System.out.println("Histogram: Categories and count");
      for (int i=0; i<CATEGORIES; i++){
        count=histogram[i];
        System.out.print(" ( "+ Math.rint(boundaries[i])+" "+Math.rint(boundaries[i+1])+" ): "+ count+ "  ");
        for (int j=0; j<count; j++){
          System.out.print("*");
        }
        System.out.println();
      } // End of for loop.
    }
    
    public static void main(String [] args){
    
      final int N =10;	     
      double [] data = new double[N];
      Random r=new Random(313); // Use 313 as a seed; it is a prime.   
      
      // Generate N random doubles,transform to lie between 0 and 10, and display.      
      System.out.println("Data to be histogrammed.");
      for (int i=0; i<N; i++){
        data[i]=r.nextDouble()*10;
        System.out.print(Math.rint(data[i])+" ");
      }
      System.out.println();
      
      Histogram histogram = new Histogram();      
      histogram.compute(data);
      histogram.display();    
    }
}