NearbyDataset

NearbyDataset.java

import java.io.PrintStream;
import java.io.PrintWriter;
import java.util.Random;

/** A class to generate somewhat larger test dataset for http://www.quora.com/challenges#nearby
 * @author Kedar Mhaswade
 */
public class NearbyDataset {
    static final Random r = new Random();
    public static void main(String[] args) {
        build(Integer.valueOf(args[0]), Integer.valueOf(args[1]), Integer.valueOf(args[2]), System.out);
    }

    private static void build(int T, int Q, int N, PrintStream out) {
        out.printf("%d %d %d%n", T, Q, N);
        double X = 1000.0, Y = 1000.0;
        buildTopics(T, X, Y, out);
        int ntq = T; // a question is tagged with about ntq topics
        buildQuestions(Q, T, ntq, out);
        int res = 100; // need res results per query
        buildQueries(N, res, X, Y, out);
    }

    private static void buildQueries(int queries, int results, double X, double Y, PrintStream out) {
        for (int i = 0; i < queries; i++) {
            //we'll build roughly half topic queries and half question queries for a random location
            char c = r.nextBoolean() ? 't' : 'q';
            int nr = r.nextInt(results + 1);
            out.printf("%c %d %.2f %.2f%n", c, nr, r.nextDouble()*X, r.nextDouble()*Y);
        }
    }

    private static void buildTopics(int t, double X, double Y, PrintStream out) {
        //locations are approximately uniformly distributed over 0.0 <= x,y <= 1000000.0 (10^6)
        //1 <= t <= 10000
        t = t > 9999 ? 9999 : t;
        for (int i = 0; i < t; i++) {
            double x = r.nextDouble() * X;
            double y = r.nextDouble() * Y;
            System.out.printf("%d %.2f %.2f%n", i, x, y);
        }
    }
    private static void buildQuestions(int q, int t, int ntq, PrintStream out) {
        for (int i = 0; i < q; i ++) { //i is the qid
            int related = r.nextInt(ntq + 1);
            out.printf("%d %d", i, related);
            int[] ints = intArray(t);
            int len = ints.length;
            for (int j = 0; j < related; j++) {
                int pid = r.nextInt(len);
                out.printf(" %d", ints[pid]);
                swap(ints, pid, len - 1);
                len -= 1;
            }
            out.println();
        }
    }

    private static void swap(int[] ints, int pid, int last) {
        int tmp = ints[pid];
        ints[pid] = ints[last];
        ints[last] = tmp;
    }

    private static int[] intArray(int t) {
        int [] ints = new int[t];
        for (int i = 0; i < t; i++)
            ints[i] = i;
        return ints;
    }
}