com.vividsolutions.jts.index.kdtree

Class KdTree


  • public class KdTree
extends Object
    An implementation of a 2-D KD-Tree. KD-trees provide fast range searching on point data.

    This implementation supports detecting and snapping points which are closer than a given distance tolerance. If the same point (up to tolerance) is inserted more than once, it is snapped to the existing node. In other words, if a point is inserted which lies within the tolerance of a node already in the index, it is snapped to that node. When a point is snapped to a node then a new node is not created but the count of the existing node is incremented. If more than one node in the tree is within tolerance of an inserted point, the closest and then lowest node is snapped to.

    • Constructor Detail

      • KdTree

        public KdTree()
        Creates a new instance of a KdTree with a snapping tolerance of 0.0. (I.e. distinct points will not be snapped)

      • KdTree

        public KdTree(double tolerance)
        Creates a new instance of a KdTree, specifying a snapping distance tolerance. Points which lie closer than the tolerance to a point already in the tree will be treated as identical to the existing point.
        Parameters:
        tolerance - the tolerance distance for considering two points equal

    • Method Detail

      • toCoordinates

        public static Coordinate[] toCoordinates(Collection kdnodes)
        Converts a collection of KdNodes to an array of Coordinates.
        Parameters:
        kdnodes - a collection of nodes
        Returns:
        an array of the coordinates represented by the nodes

      • toCoordinates

        public static Coordinate[] toCoordinates(Collection kdnodes,
                                         boolean includeRepeated)
        Converts a collection of KdNodes to an array of Coordinates, specifying whether repeated nodes should be represented by multiple coordinates.
        Parameters:
        kdnodes - a collection of nodes
        includeRepeated - true if repeated nodes should be included multiple times
        Returns:
        an array of the coordinates represented by the nodes

      • isEmpty

        public boolean isEmpty()
        Tests whether the index contains any items.
        Returns:
        true if the index does not contain any items

      • insert

        public KdNode insert(Coordinate p)
        Inserts a new point in the kd-tree, with no data.
        Parameters:
        p - the point to insert
        Returns:
        the kdnode containing the point

      • insert

        public KdNode insert(Coordinate p,
                     Object data)
        Inserts a new point into the kd-tree.
        Parameters:
        p - the point to insert
        data - a data item for the point
        Returns:
        returns a new KdNode if a new point is inserted, else an existing node is returned with its counter incremented. This can be checked by testing returnedNode.getCount() > 1.

      • query

        public void query(Envelope queryEnv,
                  KdNodeVisitor visitor)
        Performs a range search of the points in the index and visits all nodes found.
        Parameters:
        queryEnv - the range rectangle to query
        a - visitor to visit all nodes found by the search

      • query

        public List query(Envelope queryEnv)
        Performs a range search of the points in the index.
        Parameters:
        queryEnv - the range rectangle to query
        Returns:
        a list of the KdNodes found

      • query

        public void query(Envelope queryEnv,
                  List result)
        Performs a range search of the points in the index.
        Parameters:
        queryEnv - the range rectangle to query
        result - a list to accumulate the result nodes into