tsp.java

一个java的小程序,用SOM网络解决的是TSP问题.问题的大小可以自由变化,随机生成权值

import java.applet.*;
import java.util.*;
import java.awt.*;
import java.net.*;
import java.io.*;

public class TSP extends Applet implements Runnable {

	public int	NCITY = 5;
	public int	NGEONEURON;
	public static final double	COUNTRY = 1.00;
	public static final double	NEAR = 0.05;
	
  public static final Color bkC = new Color(0x000090); 	
  public static final Color bk2C = new Color(0x000050); 	
  public static final Color lnC = new Color(0xff0000); 	
  public static final Color ln2C = new Color(0xcccc00); 	
  public static final Color fgC = new Color(0xffffff); 	

	public Image   homeI,offscreen;
  public int imagewidth ,imageheight;
	public Thread  animator    = null;
	public boolean please_stop = false;
	Font mF = new Font("Courier", Font.BOLD, 12);
	Font sF = new Font("Courier", Font.BOLD, 8);
  public int counter;
	
	public City city[];
	public geoNeuron gn[];
	
	public double r[][];
	
	public double theta, phi, momentum;
	
	public Scrollbar cscroll;

    ///////////////////////////////////////////////////////////////////
    //
    //  Init section
    //
    ///////////////////////////////////////////////////////////////////

		public void kohonenInit(){
			
			theta = 0.5;
    		phi   = 0.5;
    		momentum = 0.995;
			NCITY = cscroll.getValue()/10;
			NGEONEURON = NCITY*3;
			
            city = new City[NCITY];
      		for(int i = 0; i<NCITY; i++) city[i] = new City(Math.random()*COUNTRY, Math.random()*COUNTRY);
      
      		double alpha = 0.0;      
      		gn = new geoNeuron[NGEONEURON];
      		for(int i = 0; i<NGEONEURON; i++){
        		gn[i] = new geoNeuron(0.5+0.5*Math.cos(alpha),0.5+0.5*Math.sin(alpha));
        		alpha += Math.PI *2.0 / (double)(NGEONEURON);
      		}
      
     		r = new double[NGEONEURON][NGEONEURON];
      
      		makeR(theta);        

			counter = 0;
		
		}

    ///////////////////////////////////////////////////////////////////
    //
    //  Problem section
    //
    ///////////////////////////////////////////////////////////////////
    //计算邻域关系
	public void makeR(double th){
     for(int i=0; i<NGEONEURON; i++){
      	r[i][i]= 1.0;
      	for(int j=i+1; j<NGEONEURON; j++){
      		r[i][j] = Math.exp( -1.0 * ( gn[i].dist(gn[j])*gn[i].dist(gn[j]) )/(2.0*th*th));
      		r[j][i] = r[i][j];
      	}
      }
	}

    // The body of the animator thread.
    public void run() {
    	int idx,j;
    	double x1,x2,mindist;
    	int count = 0;
        while(!please_stop) {
            counter++;
            
            // CHOSE A RANDOM PATTERN
            idx = (int)(Math.random()*NCITY);
            x1 = city[idx].x+(Math.random()*NEAR)-NEAR/2;
            x2 = city[idx].y+(Math.random()*NEAR)-NEAR/2;
            city[idx].choose++;
           
            // SEARCH FOR MINIMAL
            mindist = 100000.0;
            j = -1;
            for(int i=0; i<NGEONEURON;i++){
            	double d = (x1 - gn[i].wx)*(x1 - gn[i].wx) + (x2 - gn[i].wy)*(x2 - gn[i].wy);
            	if(d < mindist){
            		mindist = d;
            		j = i;
            	}
            }
                        
            gn[j].update++;
                     
            // UPDATE WEIGHTS
            for(int i=0; i<NGEONEURON;i++){
            	gn[i].wx += (phi * r[i][j] * (x1 - gn[i].wx));
            	gn[i].wy += (phi * r[i][j] * (x2 - gn[i].wy));
            }
                        	              
            // DECREASE LEARNING PARAMETERS
            phi *= momentum;
            theta *= momentum;
            
            // RE-COMPUTE r MATRIX
      		makeR(theta);
       		  
       		// PLOT RESULT EVERY 10 SESSIONS
       		count = (count++)%10;
       		if(count==0){
				paint(this.getGraphics());
            	try {Thread.sleep(10);} 
            	catch (InterruptedException e){};
            }
        }
        animator = null;
    }
    
    ///////////////////////////////////////////////////////////////////
    //
    //  Functional section
    //
    ///////////////////////////////////////////////////////////////////
    
    public void init() {
    
    	cscroll = new Scrollbar(Scrollbar.HORIZONTAL,NCITY*10, 10, 20, 2000);
    	cscroll.setLineIncrement(10);
    	cscroll.setPageIncrement(10);
    	add(cscroll);
    	
    	kohonenInit();	
    }

    private int toXReal(double val){int w = this.size().width;return (int)(val *((double)w/2.0-50.0) / COUNTRY +25.0);}
    private int toYReal(double val){int h = this.size().height;return (int)(val *((double)h-50.0) / COUNTRY +25.0);}
   
    
    public void paintLeft(Graphics g) {
    	Dimension size = this.size();
		int w = size.width, h = size.height;
						
		g.setFont(mF);
						
		// CLEAR ALL
        g.setColor(bkC);
        g.fillRect(0, 0, w, h);

        // DRAW GRID
        g.setColor(bk2C);
        for(double i=0; i<=COUNTRY; i+=(COUNTRY/20.0)){
        	g.drawLine(toXReal(0.0),toYReal(i),toXReal(COUNTRY),toYReal(i));
        	g.drawLine(toXReal(i),toYReal(0.0),toXReal(i),toYReal(COUNTRY));
        }
        
        //DRAW PATH
        g.setColor(lnC);
        for(int i=0; i<NGEONEURON; i++){
        	g.drawLine( toXReal(gn[i].wx),toYReal(gn[i].wy),
        	  toXReal(gn[(i+1)%NGEONEURON].wx),toYReal(gn[(i+1)%NGEONEURON].wy) );
        	//g.drawString(""+i+"-"+(gn[i].update*100/counter)+"%",toXReal(gn[i].wx),toYReal(gn[i].wy));
        }

        g.setColor(fgC);
        
        // DRAW CITYS
        for(int i=0; i<NCITY; i++){
        	g.drawOval( toXReal(city[i].x)-4, toYReal(city[i].y)-4,8,8);
        	//g.drawString(""+i+"-"+(city[i].choose*100/counter)+"%",toXReal(city[i].x),toYReal(city[i].y)+8);
        }
  	}    

    public void paint(Graphics g) {
    	Dimension size = this.size();
		int w = size.width, h = size.height;
						
		this.setBackground(bkC);

		if ((offscreen == null) || ((imagewidth != w) || (imageheight != h))) 
		{
        	offscreen = this.createImage(w, h);
        	imagewidth = w;
        	imageheight = h;
        }
						
		Rectangle clip = new Rectangle(toXReal(0),toYReal(0),toXReal(COUNTRY),toYReal(COUNTRY));
												
		Graphics goff = offscreen.getGraphics();
		goff.clipRect(clip.x, clip.y, clip.width, clip.height);
        Graphics g1 = this.getGraphics();
		g1.clipRect(clip.x, clip.y, clip.width, clip.height);
						
        paintLeft(goff);
        g1.drawImage(offscreen, 0, 0, this);
            
        clip = null;
        goff = null;
        g1 = null;
        System.gc();
            
        // CLEAR ALL
        g.setColor(bkC);
        g.fillRect(w/2+30,0,w/2+130, 20);
        g.setColor(fgC);

        g.drawString("# of city:"+cscroll.getValue()/10,w/2+30,20);

    }
 
    // Start the animation
    public void start() { 
        animator = new Thread(this);
        
        animator.start();
        
    }
    // Stop it.
    public void stop() { 
        if (animator != null) animator.stop();
        animator = null;
    }
    
    // Stop and start animating on mouse clicks.
    // if running, stop it.  Otherwise, start it.
    public boolean mouseDown(Event e, int x, int y) {
      if (animator != null){
      	please_stop = true;
      }
      else{ 
      	please_stop = false; 
		animator = new Thread(this);
		kohonenInit();
        animator.start();
      } 
      return true;
    }

}