Class MidPointOfWidestDimension

  • All Implemented Interfaces:
    Serializable

    public class MidPointOfWidestDimension
    extends KDTreeNodeSplitter
    The class that splits a KDTree node based on the midpoint value of a dimension in which the node's points have the widest spread.

    For more information see also:

    Andrew Moore (1991). A tutorial on kd-trees.

    BibTeX:

     @techreport{Moore1991,
        author = {Andrew Moore},
        booktitle = {University of Cambridge Computer Laboratory Technical Report No. 209},
        howpublished = {Extract from PhD Thesis},
        title = {A tutorial on kd-trees},
        year = {1991},
        HTTP = {http://www.autonlab.org/autonweb/14665.html}
     }
     

    Version:
    $Revision: 8034 $
    Author:
    Ashraf M. Kibriya (amk14[at-the-rate]cs[dot]waikato[dot]ac[dot]nz)
    See Also:
    Serialized Form
    • Constructor Detail

      • MidPointOfWidestDimension

        public MidPointOfWidestDimension()
    • Method Detail

      • globalInfo

        public String globalInfo()
        Returns a string describing this nearest neighbour search algorithm.
        Returns:
        a description of the algorithm for displaying in the explorer/experimenter gui
      • splitNode

        public void splitNode​(KDTreeNode node,
                              int numNodesCreated,
                              double[][] nodeRanges,
                              double[][] universe)
                       throws Exception
        Splits a node into two based on the midpoint value of the dimension in which the points have the widest spread. After splitting two new nodes are created and correctly initialised. And, node.left and node.right are set appropriately.
        Specified by:
        splitNode in class KDTreeNodeSplitter
        Parameters:
        node - The node to split.
        numNodesCreated - The number of nodes that so far have been created for the tree, so that the newly created nodes are assigned correct/meaningful node numbers/ids.
        nodeRanges - The attributes' range for the points inside the node that is to be split.
        universe - The attributes' range for the whole point-space.
        Throws:
        Exception - If there is some problem in splitting the given node.
      • rearrangePoints

        protected int rearrangePoints​(int[] indices,
                                      int startidx,
                                      int endidx,
                                      int splitDim,
                                      double splitVal)
        Re-arranges the indices array such that the points <= to the splitVal are on the left of the array and those > the splitVal are on the right.
        Parameters:
        indices - The master index array.
        startidx - The begining index of portion of indices that needs re-arranging.
        endidx - The end index of portion of indices that needs re-arranging.
        splitDim - The split dimension/attribute.
        splitVal - The split value.
        Returns:
        The startIdx of the points > the splitVal (the points belonging to the right child of the node).