bayes2d.java

A Web Tutorial on Discrete Features of Bayes Decision Theory This applet allows for the calculation

/*
 * bayes.java
 *
 * Created on April 28, 2004, 12:09 PM
 */

package applet;
import java.awt.*;
import java.applet.Applet;
import javax.swing.*; 
import java.awt.geom.*;
import java.awt.*;
import java.awt.event.*;
import java.math.*;


/**
 *
 * @author  friggi
 */
public class bayes2d extends java.applet.Applet {
    
    /** Initialization method that will be called after the applet is loaded
     *  into the browser.
     */
       /** Initialization method that will be called after the applet is loaded
     *  into the browser.
     */
    
    private double pw1;
    private double pw2;
   // private int  x2, y1, y2;
    private Graphics g1;
    
      private int   xx1 = 0;
     private int   xx2 = 0;
      private int  yy1= 0;
     private int   yy2= 0;
     
      private int   x1 = 0;
     private int   x2 = 0;
      private int  y1= 0;
     private int   y2= 0;
     
         double [] x = new double[80];
    double [] y = new double[80];
        
    public void init() {
        // TODO start asynchronous download of heavy resources
         txt_pw1 = new java.awt.TextField();
        txt_pw2 = new java.awt.TextField();
        btn_calculate = new java.awt.Button();
        scr_pw1 = new java.awt.Scrollbar();
        scr_pw2 = new java.awt.Scrollbar();
        label1 = new java.awt.Label();
        label2 = new java.awt.Label();
       /* panel1 = new java.awt.Panel();*/
        txt_q1 = new java.awt.TextField();
        txt_q2 = new java.awt.TextField();
        txt_p1 = new java.awt.TextField();
        txt_p2 = new java.awt.TextField();
        lbl_q1 = new java.awt.Label();
        lbl_q2 = new java.awt.Label();
        lbl_p1 = new java.awt.Label();
        lbl_p2 = new java.awt.Label();
        scr_p1 = new java.awt.Scrollbar();
        scr_p2 = new java.awt.Scrollbar();
        scr_q1 = new java.awt.Scrollbar();
        scr_q2 = new java.awt.Scrollbar();
        txt_answer = new java.awt.TextField();
        label3 = new java.awt.Label();
        label4 = new java.awt.Label();
        rect = new java.awt.Rectangle();

        setLayout(null);

        setForeground(java.awt.Color.black);
        
        txt_pw1.setText("0");
        txt_pw1.setBackground(new java.awt.Color(255, 255, 255));
        txt_pw1.setEditable(false);
        txt_pw1.addTextListener(new java.awt.event.TextListener() {
            public void textValueChanged(java.awt.event.TextEvent evt) {
                txt_pw1TextValueChanged(evt);
            }
        });

        add(txt_pw1);
        txt_pw1.setBounds(140, 50, 30, 20);

        txt_pw2.setText("1.0");
        txt_pw2.setBackground(new java.awt.Color(255, 255, 255));
        txt_pw2.setEditable(false);
        txt_pw2.addTextListener(new java.awt.event.TextListener() {
            public void textValueChanged(java.awt.event.TextEvent evt) {
                txt_pw2TextValueChanged(evt);
            }
        });

        add(txt_pw2);
        txt_pw2.setBounds(140, 80, 30, 20);

        btn_calculate.setLabel("Calculate");
        btn_calculate.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                btn_calculateActionPerformed(evt);
            }
        });

        add(btn_calculate);
        btn_calculate.setBounds(120, 350, 60, 24);

        scr_pw1.setBackground(new java.awt.Color(204, 204, 204));
        scr_pw1.setBlockIncrement(1);
        scr_pw1.setForeground(java.awt.Color.gray);
        scr_pw1.setMaximum(20);
        scr_pw1.setValue(0);
        scr_pw1.setOrientation(java.awt.Scrollbar.HORIZONTAL);
        scr_pw1.addAdjustmentListener(new java.awt.event.AdjustmentListener() {
            public void adjustmentValueChanged(java.awt.event.AdjustmentEvent evt) {
                scr_pw1AdjustmentValueChanged(evt);
            }
        });

        add(scr_pw1);
        scr_pw1.setBounds(180, 50, 60, 16);

        scr_pw2.setBackground(new java.awt.Color(204, 204, 204));
        scr_pw2.setBlockIncrement(1);
        scr_pw2.setForeground(java.awt.Color.lightGray);
        scr_pw2.setMaximum(20);
        scr_pw2.setValue(10);
        scr_pw2.setOrientation(java.awt.Scrollbar.HORIZONTAL);
        scr_pw2.addAdjustmentListener(new java.awt.event.AdjustmentListener() {
            public void adjustmentValueChanged(java.awt.event.AdjustmentEvent evt) {
                scr_pw2AdjustmentValueChanged(evt);
            }
        });

        add(scr_pw2);
        scr_pw2.setBounds(180, 80, 60, 16);

        label1.setText("Class 1 Prior - P(w1)");
        add(label1);
        label1.setBounds(20, 50, 118, 20);

        label2.setText("Class 2 Prior - P(w2)");
        add(label2);
        label2.setBounds(20, 80, 118, 20);

        //panel1.setBackground(new java.awt.Color(102, 102, 102));
        //add(panel1);
        //panel1.setBounds(380, 20, 380, 300);

        txt_q1.setText("0");
        txt_q1.setEditable(false);
        add(txt_q1);
        txt_q1.setBounds(210, 140, 30, 20);

        txt_q2.setText("0");
        txt_q2.setEditable(false);
        add(txt_q2);
        txt_q2.setBounds(210, 170, 30, 20);

        txt_p1.setText("0");
        txt_p1.setEditable(false);
        add(txt_p1);
        txt_p1.setBounds(50, 140, 30, 20);

        txt_p2.setText("0");
        txt_p2.setEditable(false);
        add(txt_p2);
        txt_p2.setBounds(50, 170, 30, 20);

        lbl_q1.setText("q1");
        add(lbl_q1);
        lbl_q1.setBounds(180, 140, 18, 20);

        lbl_q2.setText("q2");
        add(lbl_q2);
        lbl_q2.setBounds(180, 170, 18, 20);

        lbl_p1.setText("p1");
        add(lbl_p1);
        lbl_p1.setBounds(30, 140, 18, 20);

        lbl_p2.setText("p2");
        add(lbl_p2);
        lbl_p2.setBounds(30, 170, 18, 20);

        scr_p1.setBackground(new java.awt.Color(204, 204, 204));
        scr_p1.setBlockIncrement(1);
        scr_p1.setMaximum(20);
        scr_p1.setOrientation(java.awt.Scrollbar.HORIZONTAL);
        scr_p1.addAdjustmentListener(new java.awt.event.AdjustmentListener() {
            public void adjustmentValueChanged(java.awt.event.AdjustmentEvent evt) {
                scr_p1AdjustmentValueChanged(evt);
            }
        });

        add(scr_p1);
        scr_p1.setBounds(90, 140, 60, 16);

        scr_p2.setBackground(new java.awt.Color(204, 204, 204));
        scr_p2.setBlockIncrement(1);
        scr_p2.setMaximum(20);
        scr_p2.setOrientation(java.awt.Scrollbar.HORIZONTAL);
        scr_p2.addAdjustmentListener(new java.awt.event.AdjustmentListener() {
            public void adjustmentValueChanged(java.awt.event.AdjustmentEvent evt) {
                scr_p2AdjustmentValueChanged(evt);
            }
        });

        add(scr_p2);
        scr_p2.setBounds(90, 170, 60, 16);

        scr_q1.setBackground(new java.awt.Color(204, 204, 204));
        scr_q1.setBlockIncrement(1);
        scr_q1.setMaximum(20);
        scr_q1.setOrientation(java.awt.Scrollbar.HORIZONTAL);
        scr_q1.addAdjustmentListener(new java.awt.event.AdjustmentListener() {
            public void adjustmentValueChanged(java.awt.event.AdjustmentEvent evt) {
                scr_q1AdjustmentValueChanged(evt);
            }
        });

        add(scr_q1);
        scr_q1.setBounds(250, 140, 60, 16);

        scr_q2.setBackground(new java.awt.Color(204, 204, 204));
        scr_q2.setBlockIncrement(1);
        scr_q2.setMaximum(20);
        scr_q2.setOrientation(java.awt.Scrollbar.HORIZONTAL);
        scr_q2.addAdjustmentListener(new java.awt.event.AdjustmentListener() {
            public void adjustmentValueChanged(java.awt.event.AdjustmentEvent evt) {
                scr_q2AdjustmentValueChanged(evt);
            }
        });

        add(scr_q2);
        scr_q2.setBounds(250, 170, 60, 16);


        txt_answer.setBackground(new java.awt.Color(255, 255, 255));
        txt_answer.setEditable(false);
        add(txt_answer);
        txt_answer.setBounds(560, 350, 200, 20);

        label3.setText("Equation of Decision Boundary");
        add(label3);
        label3.setBounds(380, 350, 173, 20);

        label4.setText("where pi=P(xi=1|wi) and qi=P(xi=1|w2)");
        add(label4);
        label4.setBounds(30, 240, 280, 20); 
        
    }
    
    public void update( Graphics g)
    {
        this.g1=g;
       
       g1.draw3DRect(380, 20, 380, 300, true);
        g1.setColor(Color.white);
          g1.fill3DRect(380, 20, 380, 300, true);  
         
         //find slope and b
         double m = ((double)(y2-y1))/((double)(x2-x1));
         double b = (double) y2 - m*((double) x2);
         
         //find 4 extremum points
         double y1n = -190*m+b;
         double y2n = 190*m+b;
         double x1n = (-150 - b)/m;
         double x2n = (150 - b)/m;
         
          int [] xdraw = new int[2];
           int [] ydraw = new int[2];

           int the_temp = 0;
           
           //variables for filling areas
           boolean left = false;
           boolean right = false;
           boolean top= false;
           boolean bottom = false;
           boolean drawn = false;


    //      g1.fillPolygon(xset1, yset1, 3);
          
         if ((y1n >= -150) && (y1n <=150))
         {
             xdraw[the_temp]  = -190 +190+380;
             ydraw[the_temp]  = (int) -y1n + 150 +20;
             the_temp++;
             left = true;
             drawn = true;
         }
         
          if ((y2n >= -150) && (y2n <=150))
         {
             xdraw[the_temp] = 190 + 190+380;
             ydraw[the_temp] = (int) -y2n + 150+20;
             the_temp++;
             right = true;
             drawn = true;
         }
           
         if ((x1n >= -190) && (x1n <=190)  && (the_temp < 2))
         {
             xdraw[the_temp] = (int) x1n+ 190+380;
             ydraw[the_temp] = 150 + 150+20; //invert the y's since 0 starts from up
             the_temp++;
             bottom = true;
             drawn = true;
         }
           
          if ((x2n >= -190) && (x2n <=190) && (the_temp < 2))
         {
             xdraw[the_temp] = (int) x2n+190+380;
             ydraw[the_temp] = -150 +150+20;
             the_temp++;
             top = true;
             drawn = true;
         }
           
           //if vertical line then none apply
           if((the_temp < 2) && (x1 <= 190))
           {
               xdraw[0] = x1+190+380;
               xdraw[1] = x1+190+380;
               ydraw[0] = 320;
               ydraw[1] = 20;
               top = true;
               bottom = true;
               drawn = true;
           }
           

         //need to make x and y start at 
          
         //bounds to fill areas
         //order checked was left right bottom top, so the points placed would be in this order
         //if points are left and bottom
         if ((left == true) && (bottom == true))
         {
              int[] xset1 = {380, xdraw[0], xdraw[1]};
              int[] yset1 = {320, ydraw[0], ydraw[1]}; 
              g1.setColor(Color.pink);
              g1.fillPolygon(xset1, yset1, 3);
              
              int[] xset2 = {xdraw[0], 380, 760, 760, xdraw[1]};
              int[] yset2 = {ydraw[0], 20, 20, 320, ydraw[1]}; 
              g1.setColor(Color.YELLOW);
              g1.fillPolygon(xset2, yset2, 5);
         }
         //if points are left and right       
        if ((left == true) && (right == true))
        {
              int[] xset1 = {xdraw[0], 380, 760, xdraw[1]};
              int[] yset1 = {ydraw[0], 20, 20,  ydraw[1]}; 
              g1.setColor(Color.pink);
              g1.fillPolygon(xset1, yset1, 4);
              
              int[] xset2 = {xdraw[0], 380, 760, xdraw[1]};
              int[] yset2 = {ydraw[0], 320, 320, ydraw[1]}; 
              g1.setColor(Color.YELLOW);
              g1.fillPolygon(xset2, yset2, 4);          
        }
             
         //if points are left and top
          if ((left == true) && (top == true))
          {
              int[] xset1 = {xdraw[0], 380, xdraw[1]};
              int[] yset1 = {ydraw[0], 20, ydraw[1]}; 
              g1.setColor(Color.pink);
              g1.fillPolygon(xset1, yset1, 3);
              
              int[] xset2 = {xdraw[0], xdraw[1], 760, 760, 380};
              int[] yset2 = {ydraw[0], ydraw[1], 20, 320, 320}; 
              g1.setColor(Color.YELLOW);
              g1.fillPolygon(xset2, yset2, 5);        
          }
         //if points are right and bottom
          if ((right == true) && (bottom == true))
          {
              int[] xset1 = {xdraw[0], 760, xdraw[1]};
              int[] yset1 = {ydraw[0], 320, ydraw[1]}; 
              g1.setColor(Color.pink);
              g1.fillPolygon(xset1, yset1, 3);