weka.core.neighboursearch
Class LinearNNSearch

java.lang.Object
  extended by weka.core.neighboursearch.NearestNeighbourSearch
      extended by weka.core.neighboursearch.LinearNNSearch
All Implemented Interfaces:
java.io.Serializable, AdditionalMeasureProducer, OptionHandler, RevisionHandler

public class LinearNNSearch
extends NearestNeighbourSearch

Class implementing the brute force search algorithm for nearest neighbour search.

Valid options are:

 -S
  Skip identical instances (distances equal to zero).
 

Version:
$Revision: 1.2 $
Author:
Ashraf M. Kibriya (amk14[at-the-rate]cs[dot]waikato[dot]ac[dot]nz)
See Also:
Serialized Form

Constructor Summary
LinearNNSearch()
          Constructor.
LinearNNSearch(Instances insts)
          Constructor that uses the supplied set of instances.
 
Method Summary
 void addInstanceInfo(Instance ins)
          Adds the given instance info.
 double[] getDistances()
          Returns the distances of the k nearest neighbours.
 java.lang.String[] getOptions()
          Gets the current settings.
 java.lang.String getRevision()
          Returns the revision string.
 boolean getSkipIdentical()
          Gets whether if identical instances are skipped from the neighbourhood.
 java.lang.String globalInfo()
          Returns a string describing this nearest neighbour search algorithm.
 Instances kNearestNeighbours(Instance target, int kNN)
          Returns k nearest instances in the current neighbourhood to the supplied instance.
 java.util.Enumeration listOptions()
          Returns an enumeration describing the available options.
 Instance nearestNeighbour(Instance target)
          Returns the nearest instance in the current neighbourhood to the supplied instance.
 void setInstances(Instances insts)
          Sets the instances comprising the current neighbourhood.
 void setOptions(java.lang.String[] options)
          Parses a given list of options.
 void setSkipIdentical(boolean skip)
          Sets the property to skip identical instances (with distance zero from the target) from the set of neighbours returned.
 java.lang.String skipIdenticalTipText()
          Returns the tip text for this property.
 void update(Instance ins)
          Updates the LinearNNSearch to cater for the new added instance.
 
Methods inherited from class weka.core.neighboursearch.NearestNeighbourSearch
combSort11, distanceFunctionTipText, enumerateMeasures, getDistanceFunction, getInstances, getMeasure, getMeasurePerformance, getPerformanceStats, measurePerformanceTipText, quickSort, setDistanceFunction, setMeasurePerformance
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

LinearNNSearch

public LinearNNSearch()
Constructor. Needs setInstances(Instances) to be called before the class is usable.


LinearNNSearch

public LinearNNSearch(Instances insts)
Constructor that uses the supplied set of instances.

Parameters:
insts - the instances to use
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

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:

 -S
  Skip identical instances (distances equal to zero).
 

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.

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

skipIdenticalTipText

public java.lang.String skipIdenticalTipText()
Returns the tip text for this property.

Returns:
tip text for this property suitable for displaying in the explorer/experimenter gui

setSkipIdentical

public void setSkipIdentical(boolean skip)
Sets the property to skip identical instances (with distance zero from the target) from the set of neighbours returned.

Parameters:
skip - if true, identical intances are skipped

getSkipIdentical

public boolean getSkipIdentical()
Gets whether if identical instances are skipped from the neighbourhood.

Returns:
true if identical instances are skipped

nearestNeighbour

public Instance nearestNeighbour(Instance target)
                          throws java.lang.Exception
Returns the nearest instance in the current neighbourhood to the supplied instance.

Specified by:
nearestNeighbour in class NearestNeighbourSearch
Parameters:
target - The instance to find the nearest neighbour for.
Returns:
the nearest instance
Throws:
java.lang.Exception - if the nearest neighbour could not be found.

kNearestNeighbours

public Instances kNearestNeighbours(Instance target,
                                    int kNN)
                             throws java.lang.Exception
Returns k nearest instances in the current neighbourhood to the supplied instance.

Specified by:
kNearestNeighbours in class NearestNeighbourSearch
Parameters:
target - The instance to find the k nearest neighbours for.
kNN - The number of nearest neighbours to find.
Returns:
the k nearest neighbors
Throws:
java.lang.Exception - if the neighbours could not be found.

getDistances

public double[] getDistances()
                      throws java.lang.Exception
Returns the distances of the k nearest neighbours. The kNearestNeighbours or nearestNeighbour must always be called before calling this function. If this function is called before calling either the kNearestNeighbours or the nearestNeighbour, then it throws an exception. If, however, if either of the nearestNeighbour functions are called at any point in the past then no exception is thrown and the distances of the training set from the last supplied target instance (to either one of the nearestNeighbour functions) is/are returned.

Specified by:
getDistances in class NearestNeighbourSearch
Returns:
array containing the distances of the nearestNeighbours. The length and ordering of the array is the same as that of the instances returned by nearestNeighbour functions.
Throws:
java.lang.Exception - if called before calling kNearestNeighbours or nearestNeighbours.

setInstances

public void setInstances(Instances insts)
                  throws java.lang.Exception
Sets the instances comprising the current neighbourhood.

Overrides:
setInstances in class NearestNeighbourSearch
Parameters:
insts - The set of instances on which the nearest neighbour search is carried out. Usually this set is the training set.
Throws:
java.lang.Exception - if setting of instances fails

update

public void update(Instance ins)
            throws java.lang.Exception
Updates the LinearNNSearch to cater for the new added instance. This implementation only updates the ranges of the DistanceFunction class, since our set of instances is passed by reference and should already have the newly added instance.

Specified by:
update in class NearestNeighbourSearch
Parameters:
ins - The instance to add. Usually this is the instance that is added to our neighbourhood i.e. the training instances.
Throws:
java.lang.Exception - if the given instances are null

addInstanceInfo

public void addInstanceInfo(Instance ins)
Adds the given instance info. This implementation updates the range datastructures of the DistanceFunction class.

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.

getRevision

public java.lang.String getRevision()
Returns the revision string.

Returns:
the revision