Documentation of 'weka.core.neighboursearch.CoverTree' Java class
CoverTree
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weka.core.neighboursearch

Class CoverTree

  • All Implemented Interfaces:
    java.io.Serializable, AdditionalMeasureProducer, OptionHandler, RevisionHandler, TechnicalInformationHandler

    public class CoverTree
extends NearestNeighbourSearch
implements TechnicalInformationHandler
    Class implementing the CoverTree datastructure.
    The class is very much a translation of the c source code made available by the authors.

    For more information and original source code see:

    Alina Beygelzimer, Sham Kakade, John Langford: Cover trees for nearest neighbor. In: ICML'06: Proceedings of the 23rd international conference on Machine learning, New York, NY, USA, 97-104, 2006.

    BibTeX: 

     @inproceedings{Beygelzimer2006,
    address = {New York, NY, USA},
    author = {Alina Beygelzimer and Sham Kakade and John Langford},
    booktitle = {ICML'06: Proceedings of the 23rd international conference on Machine learning},
    pages = {97-104},
    publisher = {ACM Press},
    title = {Cover trees for nearest neighbor},
    year = {2006},
    location = {Pittsburgh, Pennsylvania},
    HTTP = {http://hunch.net/\~jl/projects/cover_tree/cover_tree.html}
 }

    Valid options are: 

     -B <value>
  Set base of the expansion constant
  (default = 1.3).
    See Also:
    Serialized Form

    • Constructor Detail

      • CoverTree

        public CoverTree()
        default constructor.

    • Method Detail

      • globalInfo

        public java.lang.String globalInfo()
        Returns a string describing this nearest neighbour search algorithm.
        Overrides:
        globalInfo in class NearestNeighbourSearch
        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

      • setOptions

        public void setOptions(java.lang.String[] options)
                throws java.lang.Exception
        Parses a given list of options.

        Valid options are: 

         -B <value>
  Set base of the expansion constant
  (default = 1.3).
        Specified by:
        setOptions in interface OptionHandler
        Overrides:
        setOptions in class NearestNeighbourSearch
        Parameters:
        options - the list of options as an array of strings
        Throws:
        java.lang.Exception - if an option is not supported

      • kNearestNeighbours

        public Instances kNearestNeighbours(Instance target,
                                    int k)
                             throws java.lang.Exception
        Returns k-NNs of a given target instance, from among the previously supplied training instances (supplied through setInstances method) P.S.: May return more than k-NNs if more one instances have the same distance to the target as the kth NN.
        Specified by:
        kNearestNeighbours in class NearestNeighbourSearch
        Parameters:
        target - The instance for which k-NNs are required.
        k - The number of k-NNs to find.
        Returns:
        The k-NN instances of the given target instance.
        Throws:
        java.lang.Exception - If there is some problem find the k-NNs.

      • nearestNeighbour

        public Instance nearestNeighbour(Instance target)
                          throws java.lang.Exception
        Returns the NN instance of a given target instance, from among the previously supplied training instances.
        Specified by:
        nearestNeighbour in class NearestNeighbourSearch
        Parameters:
        target - The instance for which NN is required.
        Returns:
        The NN instance of the target instance.
        Throws:
        java.lang.Exception - If there is some problem finding the nearest neighbour.

      • getDistances

        public double[] getDistances()
                      throws java.lang.Exception
        Returns the distances of the (k)-NN(s) found earlier by kNearestNeighbours()/nearestNeighbour().
        Specified by:
        getDistances in class NearestNeighbourSearch
        Returns:
        The distances (in the same order) of the k-NNs.
        Throws:
        java.lang.Exception - If the tree hasn't been built (by calling setInstances()), or none of kNearestNeighbours() or nearestNeighbour() has been called before.

      • setInstances

        public void setInstances(Instances instances)
                  throws java.lang.Exception
        Builds the Cover Tree on the given set of instances.
        Overrides:
        setInstances in class NearestNeighbourSearch
        Parameters:
        instances - The insts on which the Cover Tree is to be built.
        Throws:
        java.lang.Exception - If some error occurs while building the Cover Tree

      • update

        public void update(Instance ins)
            throws java.lang.Exception
        Adds an instance to the cover tree. P.S.: The current version doesn't allow addition of instances after batch construction.
        Specified by:
        update in class NearestNeighbourSearch
        Parameters:
        ins - The instance to add.
        Throws:
        java.lang.Exception - Alway throws this, as current implementation doesn't allow addition of instances after building.

      • addInstanceInfo

        public void addInstanceInfo(Instance ins)
        Adds the given instance info. This implementation updates only the range datastructures of the EuclideanDistance. Nothing is required to be updated in the built Cover Tree.
        Overrides:
        addInstanceInfo in class NearestNeighbourSearch
        Parameters:
        ins - The instance to add the information of. Usually this is the test instance supplied to update the range of attributes in the distance function.

      • setDistanceFunction

        public void setDistanceFunction(DistanceFunction df)
                         throws java.lang.Exception
        Sets the distance function to use for nearest neighbour search. Currently only EuclideanDistance is supported.
        Overrides:
        setDistanceFunction in class NearestNeighbourSearch
        Parameters:
        df - the distance function to use
        Throws:
        java.lang.Exception - if not EuclideanDistance

      • baseTipText

        public java.lang.String baseTipText()
        Returns the tip text for this property.
        Returns:
        tip text for this property suitable for displaying in the explorer/experimenter gui

      • getBase

        public double getBase()
        Returns the base in use for expansion constant.
        Returns:
        base currently in use.

      • setBase

        public void setBase(double b)
        Sets the base to use for expansion constant. The 2 in 2^i in the paper.
        Parameters:
        b - the new base;

      • measureTreeSize

        public double measureTreeSize()
        Returns the size of the tree. (number of internal nodes + number of leaves)
        Returns:
        the size of the tree

      • measureNumLeaves

        public double measureNumLeaves()
        Returns the number of leaves.
        Returns:
        the number of leaves

      • measureMaxDepth

        public double measureMaxDepth()
        Returns the depth of the tree.
        Returns:
        the number of rules

      • getMeasure

        public double getMeasure(java.lang.String additionalMeasureName)
        Returns the value of the named measure.
        Specified by:
        getMeasure in interface AdditionalMeasureProducer
        Overrides:
        getMeasure in class NearestNeighbourSearch
        Parameters:
        additionalMeasureName - the name of the measure to query for its value
        Returns:
        the value of the named measure
        Throws:
        java.lang.IllegalArgumentException - if the named measure is not supported

      • getRevision

        public java.lang.String getRevision()
        Returns the revision string.
        Specified by:
        getRevision in interface RevisionHandler
        Returns:
        the revision

      • main

        public static void main(java.lang.String[] args)
        Method for testing the class from command line.
        Parameters:
        args - The supplied command line arguments.
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