//Correlation.java

import javax.swing.*;
import java.awt.*;
import java.text.*;
import java.util.*;

public class Correlation extends JApplet {
//    public  void init () {
    public static void main(String[] argv) {

	JTextArea textarea = new JTextArea(30,60);
	textarea.setLineWrap( true );
	textarea.setFont( new Font("Courier",Font.BOLD,14) );
	JScrollPane scrollpane = new JScrollPane(textarea);
    	DecimalFormat d4 = new DecimalFormat ("0.0000");

	String input;
	StringTokenizer st;
	double x, xa, xb;
	
	input = JOptionPane.showInputDialog("Enter/paste your data of first data set separated by spaces");//,
        st = new StringTokenizer(input);
        ArrayList A = new ArrayList();
        while (st.hasMoreTokens()) {
            x = Double.parseDouble(st.nextToken());
            A.add(x);
        }
	
	input = JOptionPane.showInputDialog("Enter/paste your data of second data set separated by spaces");//,
        st = new StringTokenizer(input);
        ArrayList B = new ArrayList();
        while (st.hasMoreTokens()) {
            x = Double.parseDouble(st.nextToken());
            B.add(x);
        }
/*

	for (int i=0; i<A.length; i++) {	
	    //A and B random:  r=about 0
	    A[i] = (int)(Math.random() * range);
	    B[i] = (int)(Math.random() * range);
	   
	    //B[i] = range / 2;  //sumy2==sumy*sumy/N   /sqrt(0) r=NaN
	   
	    //A[i] = B[i] = i;  //r=1
	   
	    //A[i] = i;   B[i] = 10*i;  //r=1
	   
	    //A[i] = B[A.length-1-i] = i;  //r=-1
	    
	    // A[i] = i;  B[A.length-1-i] = 10*i;  //r=-1
	}

	int showData;
	showData = JOptionPane.showConfirmDialog(null,"Show the data?",
						 "show the data?",
						 JOptionPane.YES_NO_OPTION);
	if (showData == JOptionPane.YES_OPTION) {
	    for (int i=0; i<A.length; i++)
		textarea.append(A[i] + " ");  
	    textarea.append("\n\n");  
	    for (int i=0; i<B.length; i++)
		textarea.append(B[i] + " ");  
	    textarea.append("\n\n");  
	}
*/

        Iterator dataItA =  A.iterator();
        Iterator dataItB =  B.iterator();
        double sumx=0, sumy=0, sumx2=0, sumy2=0, sumxy=0;
        while (dataItA.hasNext() && dataItB.hasNext()) {
            xa = (Double)dataItA.next();  
            xb = (Double)dataItB.next();  
	    sumx += xa;
	    sumx2 += xa*xa;
	    sumy += xb;
	    sumy2 += xb*xb;
	    sumxy += xa*xb;
	}
	int N = A.size();
	double xu = sumx / N;
	double yu = sumy / N;
	double xsigma = Math.sqrt((sumx2 - N*(xu*xu)) / N ); 
	double ysigma = Math.sqrt((sumy2 - N*(yu*yu)) / N ); 

	double r = (sumxy/N-(xu*yu)) / (xsigma*ysigma);
	
	double m = r * (ysigma/xsigma);
	double b = yu - m * xu;

	textarea.append("\nx\u0304= "+d4.format(xu)+"   \u03C3x= "+d4.format(xsigma));
	textarea.append("\ny\u0304= "+d4.format(yu)+"   \u03C3y= "+d4.format(ysigma));
	textarea.append("\nPearson correlation r= "+d4.format(r));
	textarea.append("\nLinear regression line y= "+d4.format(m)+"x + " + d4.format(b));
	
	//***********************************
	//Spearman rank correlation
	//don't assume no ties, so do Pearson of ranks
	ArrayList Ys = (ArrayList)(B.clone());  //copy of B 
	
	//JOptionPane.showMessageDialog(null,"B[0]="+B.get(0)+"   Y[0]="+Ys.get(0));
	Collections.sort(Ys);  //B not sorted
	//JOptionPane.showMessageDialog(null,"B[0]="+B.get(0)+"   Y[0]="+Ys.get(0));
	
	//hand sort A, carrying B's pair with it
	//a sort that minimizes arraylist disruption?
	int minJ;
	Double temp;
	for (int i=0; i<A.size(); i++) {
	    minJ = i;  //selectee's index
	    for (int j=i+1; j<A.size(); j++)  //find where it should go/swap with
	        if (((Double)(A.get(j))).doubleValue() < ((Double)(A.get(minJ))).doubleValue())
	            minJ = j;
	    temp = (Double)(A.get(i));
	    A.set(i,A.get(minJ));
	    A.set(minJ,temp);

	    temp = (Double)(B.get(i));
	    B.set(i,B.get(minJ));
	    B.set(minJ,temp);
	    
	}
	/*String outputtest="";
	for (int i=0; i<A.size(); i++)
	    outputtest += " "+A.get(i);
	JOptionPane.showMessageDialog(null,outputtest);
	*/
	double mid = (A.size() -1) / 2.0;
	double sumProd=0, sumXdiffSqrd=0, sumYdiffSqrd=0;
	//for each ranked X find its pair rank Y
	for (int xi=0; xi<A.size(); xi++) {
	    int y = 0;
	    boolean found = false;
	    while (!found)
	    	if (((Double)(Ys.get(y))).doubleValue() == ((Double)(B.get(xi))).doubleValue())
	    	    found = true;
	    	else
	    	    y++;
	    sumProd += (xi-mid)*(y-mid);
	    sumXdiffSqrd += (xi-mid)*(xi-mid);
	    sumYdiffSqrd += (y-mid)*(y-mid);
	    
	}
	double rho = sumProd / Math.sqrt(sumXdiffSqrd*sumYdiffSqrd);

	textarea.append("\n\nSpearman rank correlation coefficient   \u03C1= "+d4.format(rho));



	JOptionPane.showMessageDialog(null, 
				      scrollpane,
				      "Correlation",
				      JOptionPane.PLAIN_MESSAGE);
    }
}