// T wo dimensional Hopfield net demonstration
import java.awt.*;
import java.io.*;
import java.applet.*;
import java.util.*;
public class hop2d extends Applet
{ static final int MAXPATTERNS = 4;
static final int ROWS = 8; // Dimensions of the images
static final int COLS = 8;
static final int MAINSCREEN = 0; // Constants for drawing the screens
static final int TRAINPATTS = 1;
Button viewTrainPattern; // Click on this button to view the training patterns
Button singleStep; // Click on this button to run a test one (more) step
int trainPatterns[][][] = new int [MAXPATTERNS][COLS][ROWS];
int testPattern[][] = new int [COLS][ROWS];
int t[][][][] = new int [COLS][ROWS][COLS][ROWS]; // connection weights
int screenMode = MAINSCREEN;
public void init ()
{ setBackground(Color.cyan);
singleStep = new Button("Single Step");
add(singleStep);
viewTrainPattern = new Button("View Training Patterns");
add(viewTrainPattern);
setupTrainingPatterns();
// Initialise test pattern to blank
for (int i = 0; i < COLS; i++)
for (int j = 0; j < ROWS; j++)
testPattern[i][j] = -1;
}
public void paint (Graphics g)
{ switch (screenMode)
{ case MAINSCREEN : drawMainScreen(g); break;
case TRAINPATTS : drawTrainingPatterns(g); break;
}
}
public void drawMainScreen (Graphics g)
{ g.drawString("Test pattern",50,40);
for (int j = 0; j < ROWS; j++)
for (int i = 0; i < COLS; i++)
drawCell(g,testPattern[i][j],50 + 12 * i, 50 + 12 * j);
}
public void drawTrainingPatterns (Graphics g)
{ for (int pattern = 0; pattern < MAXPATTERNS; pattern++)
{ g.drawString("Pattern " + pattern, 5 + 110 * pattern, 45);
for (int i = 0; i < COLS; i++)
for (int j = 0; j < ROWS; j++)
drawCell(g, trainPatterns[pattern][i][j],5 + 110 * pattern + 12 * i, 50 + 12 * j);
}
}
// Draw a particular value of 1 or -1
public void drawCell (Graphics g, int value, int x, int y)
{ if (value == 1)
g.setColor(Color.black);
else
g.setColor(Color.white);
g.fillOval(x,y,12,12); // Draws a white circle or a black one
g.setColor(Color.black);
g.drawOval(x,y,12,12);
}
// Process the button clicks
public boolean action (Event e, Object arg)
{ if (e.target == viewTrainPattern)
{ if (viewTrainPattern.getLabel() == "View Training Patterns")
{ viewTrainPattern.setLabel("View Main Screen");
screenMode = TRAINPATTS;
repaint();
}
else
{ viewTrainPattern.setLabel("View Training Patterns");
screenMode = MAINSCREEN;
repaint();
}
}
if (e.target == singleStep)
{ runSingleStep();
repaint();
}
return true;
}
// Handle general mouse clicks depending on the drawing mode
public boolean mouseDown (Event event, int x, int y)
{ switch (screenMode)
{ case MAINSCREEN : mouseMainScreen(x,y); break;
case TRAINPATTS : mouseTrain(x,y); break;
}
return true;
}
public void mouseMainScreen (int x, int y)
{ boolean redrawNeeded = false;
for (int i = 0; i < COLS; i++)
for (int j = 0; j< ROWS; j++)
if (x > 50 + i * 12 && x < 62 + i * 12 && y > 50 + j * 12 && y < 62 + j * 12)
{ testPattern[i][j] = - testPattern[i][j];
redrawNeeded = true;
}
if (redrawNeeded == true)
repaint();
}
public void mouseTrain (int x, int y)
{ boolean redrawNeeded = false;
for (int pattern = 0; pattern < MAXPATTERNS; pattern++)
for (int i = 0; i < COLS; i++)
for (int j = 0; j < ROWS; j++)
if (x > 5 + 110 * pattern + 12 * i && x < 17 + 110 * pattern + 12 * i &&
y > 50 + 12 * j && y < 62 + 12 * j)
{ trainPatterns[pattern][i][j] = - trainPatterns[pattern][i][j]; // Swap -1 to 1 and vice-versa
redrawNeeded = true;
}
if (redrawNeeded == true)
{ retrain();
repaint();
}
}
public void runSingleStep ()
{ int new_mu[][] = new int[COLS][ROWS]; // Holds new values of mu before copying back
int i,j,k,l; // FOR loop counters
for (k = 0; k < COLS; k++)
for (l = 0; l < ROWS; l++)
{ int sum = 0;
for (i = 0; i < COLS; i++)
for (j = 0; j < ROWS; j++)
sum += t[i][j][k][l] * testPattern[i][j];
if (sum > 0) // Pass through hard-limiting non-linearity
new_mu[k][l] = 1;
else
new_mu[k][l] = -1;
}
// Now copy the values present in new_mu back into the test pattern ready to be displayed
for (i = 0; i < COLS; i++)
for (j = 0; j < ROWS; j++)
testPattern[i][j] = new_mu[i][j];
repaint();
}
public void setupTrainingPatterns ()
{ initialisePattern(0,"00000000","01111110","01000010","01000010","01000010","01000010",
"01111110","00000000");
initialisePattern(1,"00000000","00010000","00010000","00010000","11111110","00010000",
"00010000","00010000");
initialisePattern(2,"10011110","10010010","10010010","10010010","10010010","10010010",
"10010010","11110011");
initialisePattern(3,"00000000","00010000","00011000","00100100","00100100","01000010",
"01000010","11111111");
retrain();
}
public void initialisePattern (int patNum, String line0, String line1, String line2, String line3,
String line4, String line5, String line6, String line7)
{ initialiseline(patNum,0,line0);
initialiseline(patNum,1,line1);
initialiseline(patNum,2,line2);
initialiseline(patNum,3,line3);
initialiseline(patNum,4,line4);
initialiseline(patNum,5,line5);
initialiseline(patNum,6,line6);
initialiseline(patNum,7,line7);
}
public void initialiseline (int patNum, int lineNum, String line)
{ for (int i = 0; i < line.length(); i++)
if (line.charAt(i) == '1')
trainPatterns[patNum][i][lineNum] = +1;
else
trainPatterns[patNum][i][lineNum] = -1;
}
public void retrain ()
{ for (int i = 0; i < COLS; i++)
for (int j = 0; j < ROWS; j++)
for (int k = 0; k < COLS; k++)
for (int l = 0; l < ROWS; l++)
if (i == k && j == l)
t[i][j][k][l] = 0;
else
{ int sum = 0;
for (int pattern = 0; pattern < MAXPATTERNS; pattern++)
sum += trainPatterns[pattern][i][j] * trainPatterns[pattern][k][l];
t[i][j][k][l] = sum;
}
}
}
