import edu.princeton.cs.algs4.In;
import edu.princeton.cs.algs4.StdDraw;
import java.awt.Color;
public class WeakLearnerVisualizer {
public static void main(String[] args) {
// Define colors
Color LIGHT_BLUE = Color.decode("#7faac9");
Color LIGHT_RED = Color.decode("#e5b4b8");
Color BLUE = Color.decode("#005493");
Color RED = Color.decode("#8d3138");
// Read input file
In datafile = new In(args[0]);
int n = datafile.readInt(); // number of points
int k = datafile.readInt(); // dimensions
if (k != 2) {
throw new IllegalArgumentException("Only 2D data is supported for visualization.");
}
int[][] input = new int[n][k];
for (int i = 0; i < n; i++) {
for (int j = 0; j < k; j++) {
input[i][j] = datafile.readInt();
}
}
int[] labels = new int[n];
for (int i = 0; i < n; i++) {
labels[i] = datafile.readInt();
}
double[] weights = new double[n];
for (int i = 0; i < n; i++) {
weights[i] = datafile.readDouble();
}
WeakLearner weakLearner = new WeakLearner(input, weights, labels);
// Get decision stump parameters
int dimension = weakLearner.dimensionPredictor(); // dp
int value = weakLearner.valuePredictor(); // vp
int sign = weakLearner.signPredictor(); // sp
// Determine plot boundaries
int minX = Integer.MAX_VALUE, maxX = Integer.MIN_VALUE;
int minY = Integer.MAX_VALUE, maxY = Integer.MIN_VALUE;
for (int i = 0; i < n; i++) {
minX = Math.min(minX, input[i][0]);
maxX = Math.max(maxX, input[i][0]);
minY = Math.min(minY, input[i][1]);
maxY = Math.max(maxY, input[i][1]);
}
// Add a buffer of 1 unit
minX -= 1;
maxX += 1;
minY -= 1;
maxY += 1;
// Compute accuracy
double accuracy = 0.0;
for (int i = 0; i < n; i++) {
int predictedLabel = weakLearner.predict(input[i]);
if (predictedLabel == labels[i]) {
accuracy += weights[i];
}
}
// Set up StdDraw canvas
StdDraw.setCanvasSize(800, 800); // Larger canvas
StdDraw.setXscale(minX - 1, maxX + 1); // Expand the range for axes arrows
StdDraw.setYscale(minY - 1, maxY + 1);
StdDraw.clear();
// Draw shaded regions
if (dimension == 0) { // Vertical split
if (sign == 0) {
StdDraw.setPenColor(LIGHT_BLUE);
StdDraw.filledRectangle((minX + value) / 2.0, (minY + maxY) / 2.0, (value - minX) / 2.0, (maxY - minY) / 2.0);
StdDraw.setPenColor(LIGHT_RED);
StdDraw.filledRectangle((value + maxX) / 2.0, (minY + maxY) / 2.0, (maxX - value) / 2.0, (maxY - minY) / 2.0);
} else {
StdDraw.setPenColor(LIGHT_RED);
StdDraw.filledRectangle((minX + value) / 2.0, (minY + maxY) / 2.0, (value - minX) / 2.0, (maxY - minY) / 2.0);
StdDraw.setPenColor(LIGHT_BLUE);
StdDraw.filledRectangle((value + maxX) / 2.0, (minY + maxY) / 2.0, (maxX - value) / 2.0, (maxY - minY) / 2.0);
}
} else if (dimension == 1) { // Horizontal split
if (sign == 0) {
StdDraw.setPenColor(LIGHT_BLUE);
StdDraw.filledRectangle((minX + maxX) / 2.0, (minY + value) / 2.0, (maxX - minX) / 2.0, (value - minY) / 2.0);
StdDraw.setPenColor(LIGHT_RED);
StdDraw.filledRectangle((minX + maxX) / 2.0, (value + maxY) / 2.0, (maxX - minX) / 2.0, (maxY - value) / 2.0);
} else {
StdDraw.setPenColor(LIGHT_RED);
StdDraw.filledRectangle((minX + maxX) / 2.0, (minY + value) / 2.0, (maxX - minX) / 2.0, (value - minY) / 2.0);
StdDraw.setPenColor(LIGHT_BLUE);
StdDraw.filledRectangle((minX + maxX) / 2.0, (value + maxY) / 2.0, (maxX - minX) / 2.0, (maxY - value) / 2.0);
}
}
// Draw grid
StdDraw.setPenColor(StdDraw.LIGHT_GRAY);
for (int x = minX; x <= maxX; x++) {
StdDraw.line(x, minY, x, maxY);
}
for (int y = minY; y <= maxY; y++) {
StdDraw.line(minX, y, maxX, y);
}
// Draw axes with arrowheads
StdDraw.setPenColor(StdDraw.BLACK);
StdDraw.setPenRadius(0.01); // Thicker axes
double arrowSize = 0.3; // Size of arrowhead
// x-axis
StdDraw.line(0, 0, maxX + 0.5 - arrowSize, 0);
StdDraw.filledPolygon(
new double[]{maxX + 0.5, maxX + 0.5 - arrowSize, maxX + 0.5 - arrowSize},
new double[]{0, arrowSize / 2, -arrowSize / 2}
);
// y-axis
StdDraw.line(0, 0, 0, maxY + 0.5 - arrowSize);
StdDraw.filledPolygon(
new double[]{0, arrowSize / 2, -arrowSize / 2},
new double[]{maxY + 0.5, maxY + 0.5 - arrowSize, maxY + 0.5 - arrowSize}
);
// Axis labels
StdDraw.setFont(StdDraw.getFont().deriveFont(20f)); // Larger font size
StdDraw.setPenColor(StdDraw.BLACK);
StdDraw.text(maxX + 0.7, -0.3, "x");
StdDraw.text(-0.3, maxY + 0.7, "y");
// Draw decision stump line
StdDraw.setPenColor(StdDraw.BLACK);
StdDraw.setPenRadius(0.005); // Thinner than axes
if (dimension == 0) {
StdDraw.line(value, minY - 0.2, value, maxY + 0.2); // Vertical line
} else if (dimension == 1) {
StdDraw.line(minX - 0.2, value, maxX + 0.2, value); // Horizontal line
}
// Draw the input points
StdDraw.setPenRadius(0.01);
for (int i = 0; i < n; i++) {
if (labels[i] == 0) {
StdDraw.setPenColor(BLUE);
StdDraw.filledSquare(input[i][0], input[i][1], 0.1);
} else if (labels[i] == 1) {
StdDraw.setPenColor(RED);
StdDraw.filledCircle(input[i][0], input[i][1], 0.1);
}
}
// Display accuracy and predictor parameters at the bottom
StdDraw.setFont(StdDraw.getFont().deriveFont(18f)); // Font size for text
StdDraw.setPenColor(StdDraw.BLACK); // Black text
double textHeight = minY - 0.3; // Adjusted text height for visibility
StdDraw.text((minX + maxX) / 2.0, textHeight, String.format("Accuracy: %.2f", accuracy));
StdDraw.text((minX + maxX) / 2.0, textHeight - 0.5, String.format("vp: %d, dp: %d, sp: %d", value, dimension, sign));
StdDraw.show();
}
}
