コード例 #1
0
  public static void main(String[] args) {

    // Handle invalid arguments..
    if (args.length < 2) {
      System.out.println("Usage: ConvexHull arg1 arg2");
      System.out.println("arg1: input dataset A file path [points]");
      System.out.println("arg2: output file name and path");
      System.exit(1);
    }

    // Creating and setting sparkconf
    SparkConf sparkConf = new SparkConf().setAppName("Group3-edu.asu.cse512.ConvexHull");
    JavaSparkContext sc = new JavaSparkContext(sparkConf);

    // Adding external jars
    // sc.addJar("lib/jts-1.13.jar");

    JavaRDD<String> lines = sc.textFile(args[0]);
    // Using mapPartitions function to find convex hull points in distributed environment
    JavaRDD<Coordinate> hullPointsRDD = lines.mapPartitions(new ConvexH());
    List<Coordinate> hullPointsList = hullPointsRDD.collect();
    Coordinate[] inputArray = new Coordinate[hullPointsList.size()];
    int j = 0;
    for (Coordinate c : hullPointsList) {
      inputArray[j] = c;
      j++;
    }
    // Finding convex hull points on the final subset of points retrieved from distributed
    // environment
    GeometryFactory geoFactory1 = new GeometryFactory();
    MultiPoint mPoint1 = geoFactory1.createMultiPoint(inputArray);
    Geometry geo1 = mPoint1.convexHull();
    Coordinate[] convexHullResult = geo1.getCoordinates();
    int length = convexHullResult.length;
    Coordinate[] convexHullFinalResult = Arrays.copyOf(convexHullResult, length - 1);
    Arrays.sort(convexHullFinalResult);

    // Converting the list of coordinates into Coordinate RDD
    JavaRDD<Coordinate> convexHullResultRDD =
        sc.parallelize(Arrays.asList(convexHullFinalResult), 1);
    JavaRDD<String> convexHullResultString =
        convexHullResultRDD
            .repartition(1)
            .map(
                new Function<Coordinate, String>() {
                  public String call(Coordinate hullPoint) throws Exception {

                    return hullPoint.x + "," + hullPoint.y;
                  }
                });
    // Save the String RDD into text file. Using repartition(1) to preserve the order of coordinates
    convexHullResultString.repartition(1).saveAsTextFile(args[1]);
  }
コード例 #2
0
  public Iterable<Coordinate> call(Iterator<String> coordinatesIterator) throws Exception {
    // TODO Auto-generated method stub
    List<Coordinate> coorList = new ArrayList<Coordinate>();

    // Retrieving points from JavaRDD<String> and storing it in a list
    while (coordinatesIterator.hasNext()) {
      String[] temp = coordinatesIterator.next().split(",");
      coorList.add(new Coordinate(Double.parseDouble(temp[0]), Double.parseDouble(temp[1])));
    }
    Coordinate[] coorArray = new Coordinate[coorList.size()];
    int i = 0;
    for (Coordinate c : coorList) {
      coorArray[i] = c;
      i++;
    }
    // Using Geometry class of JTS library to find convex hull points
    GeometryFactory geoFactory = new GeometryFactory();
    MultiPoint mPoint = geoFactory.createMultiPoint(coorArray);
    Geometry geo = mPoint.convexHull();
    Coordinate[] convexResult = geo.getCoordinates();
    return Arrays.asList(convexResult);
  }