Package weka.core.neighboursearch.kdtrees

Class MedianOfWidestDimension

java.lang.Object
weka.core.neighboursearch.kdtrees.KDTreeNodeSplitter
weka.core.neighboursearch.kdtrees.MedianOfWidestDimension
All Implemented Interfaces:
Serializable, OptionHandler, RevisionHandler, TechnicalInformationHandler
public class MedianOfWidestDimension extends KDTreeNodeSplitter implements TechnicalInformationHandler
The class that splits a KDTree node based on the median value of a dimension in which the node's points have the widest spread.

For more information see also:

Jerome H. Friedman, Jon Luis Bentley, Raphael Ari Finkel (1977). An Algorithm for Finding Best Matches in Logarithmic Expected Time. ACM Transactions on Mathematics Software. 3(3):209-226.

BibTeX: 

 @article{Friedman1977,
    author = {Jerome H. Friedman and Jon Luis Bentley and Raphael Ari Finkel},
    journal = {ACM Transactions on Mathematics Software},
    month = {September},
    number = {3},
    pages = {209-226},
    title = {An Algorithm for Finding Best Matches in Logarithmic Expected Time},
    volume = {3},
    year = {1977}
 }

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

  • Constructor Details

    • MedianOfWidestDimension

      public MedianOfWidestDimension()

  • Method Details

    • 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

    • getTechnicalInformation

      public TechnicalInformation getTechnicalInformation()
      Returns an instance of a TechnicalInformation object, containing detailed information about the technical background of this class, e.g., paper reference or book this class is based on.
      Specified by:
      getTechnicalInformation in interface TechnicalInformationHandler
      Returns:
      the technical information about this class

    • splitNode

      public void splitNode(KDTreeNode node, int numNodesCreated, double[][] nodeRanges, double[][] universe) throws Exception
      Splits a node into two based on the median 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.

    • select

      public int select(int attIdx, int[] indices, int left, int right, int k)
      Implements computation of the kth-smallest element according to Manber's "Introduction to Algorithms".
      Parameters:
      attIdx - The dimension/attribute of the instances in which to find the kth-smallest element.
      indices - The master index array containing indices of the instances.
      left - The begining index of the portion of the master index array in which to find the kth-smallest element.
      right - The end index of the portion of the master index array in which to find the kth-smallest element.
      k - The value of k
      Returns:
      The index of the kth-smallest element

    • getRevision

      public String getRevision()
      Returns the revision string.
      Specified by:
      getRevision in interface RevisionHandler
      Overrides:
      getRevision in class KDTreeNodeSplitter
      Returns:
      the revision