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## weka.core.neighboursearch
Class CoverTree

    java.lang.Object
      weka.core.neighboursearch.NearestNeighbourSearch
          weka.core.neighboursearch.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).

Version:
  $Revision: 1.4 $
Author:
  Alina Beygelzimer (original C++ code), Sham Kakade (original C++ code), John Langford (original C++ code), Ashraf M. Kibriya (amk14[at-the-rate]cs[dot]waikato[dot]ac[dot]nz) (Java port)
See Also:
  Serialized Form

Nested Class Summary
`class` | `CoverTree.CoverTreeNode` class representing a node of the cover tree.

Constructor Summary
`CoverTree()` default constructor.

Method Summary
`void` | `addInstanceInfo(Instance ins)` Adds the given instance info.
`java.lang.String` | `baseTipText()` Returns the tip text for this property.
`java.util.Enumeration` | `enumerateMeasures()` Returns an enumeration of the additional measure names.
`double` | `getBase()` Returns the base in use for expansion constant.
`double[]` | `getDistances()` Returns the distances of the (k)-NN(s) found earlier by kNearestNeighbours()/nearestNeighbour().
`double` | `getMeasure(java.lang.String additionalMeasureName)` Returns the value of the named measure.
`java.lang.String[]` | `getOptions()` Gets the current settings of KDtree.
`java.lang.String` | `getRevision()` Returns the revision string.
`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.
`java.lang.String` | `globalInfo()` Returns a string describing this nearest neighbour search algorithm.
`Instances` | `kNearestNeighbours(Instance target, int k)` 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.
`java.util.Enumeration` | `listOptions()` Returns an enumeration describing the available options.
`static void` | `main(java.lang.String[] args)` Method for testing the class from command line.
`double` | `measureMaxDepth()` Returns the depth of the tree.
`double` | `measureNumLeaves()` Returns the number of leaves.
`double` | `measureTreeSize()` Returns the size of the tree.
`Instance` | `nearestNeighbour(Instance target)` Returns the NN instance of a given target instance, from among the previously supplied training instances.
`void` | `setBase(double b)` Sets the base to use for expansion constant.
`void` | `setDistanceFunction(DistanceFunction df)` Sets the distance function to use for nearest neighbour search.
`void` | `setInstances(Instances instances)` Builds the Cover Tree on the given set of instances.
`void` | `setOptions(java.lang.String[] options)` Parses a given list of options.
`void` | `update(Instance ins)` Adds an instance to the cover tree.

Methods inherited from class weka.core.neighboursearch.NearestNeighbourSearch
`combSort11, distanceFunctionTipText, getDistanceFunction, getInstances, getMeasurePerformance, getPerformanceStats, measurePerformanceTipText, quickSort, setMeasurePerformance`

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

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

### listOptions

    public java.util.Enumeration listOptions()

  Returns an enumeration describing the available options.

  Specified by:
    `listOptions` in interface `OptionHandler`
  Overrides:
    `listOptions` in class `NearestNeighbourSearch`
  Returns:
    an enumeration of all the available options.

### 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

### getOptions

    public java.lang.String[] getOptions()

  Gets the current settings of KDtree.

  Specified by:
    `getOptions` in interface `OptionHandler`
  Overrides:
    `getOptions` in class `NearestNeighbourSearch`
  Returns:
    an array of strings suitable for passing to setOptions

### 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

### enumerateMeasures

    public java.util.Enumeration enumerateMeasures()

  Returns an enumeration of the additional measure names.

  Specified by:
    `enumerateMeasures` in interface `AdditionalMeasureProducer`
  Overrides:
    `enumerateMeasures` in class `NearestNeighbourSearch`
  Returns:
    an enumeration of the measure names

### 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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