/****************************************************************************** * Compilation: javac NearestNeighborVisualizer.java * Execution: java NearestNeighborVisualizer input.txt * Dependencies: PointST.java KdTreeST.java * * Read points from a file (specified as a command-line argument) and * draw to standard draw. Highlight the closest point to the mouse. * * The nearest neighbor according to the brute-force algorithm is drawn * in red; the nearest neighbor using the kd-tree algorithm is drawn in blue. * ******************************************************************************/ import edu.princeton.cs.algs4.In; import edu.princeton.cs.algs4.Point2D; import edu.princeton.cs.algs4.StdDraw; public class NearestNeighborVisualizer { public static void main(String[] args) { String filename = args[0]; In in = new In(filename); // initialize the two data structures with point from standard input PointST brute = new PointST(); KdTreeST kdtree = new KdTreeST(); for (int i = 0; !in.isEmpty(); i++) { double x = in.readDouble(); double y = in.readDouble(); Point2D p = new Point2D(x, y); kdtree.put(p, i); brute.put(p, i); } // process nearest neighbor queries StdDraw.enableDoubleBuffering(); while (true) { // the location (x, y) of the mouse double x = StdDraw.mouseX(); double y = StdDraw.mouseY(); Point2D query = new Point2D(x, y); // draw all of the points StdDraw.clear(); StdDraw.setPenColor(StdDraw.BLACK); StdDraw.setPenRadius(0.01); for (Point2D p : brute.points()) p.draw(); // draw in red the nearest neighbor according to the brute-force algorithm StdDraw.setPenRadius(0.03); StdDraw.setPenColor(StdDraw.RED); brute.nearest(query).draw(); StdDraw.setPenRadius(0.02); // draw in blue the nearest neighbor according to the kd-tree algorithm StdDraw.setPenColor(StdDraw.BLUE); kdtree.nearest(query).draw(); StdDraw.show(); StdDraw.pause(20); } } }