classifiers.usm.distance
Class USMStringDistance

java.lang.Object
  |
  +--coreComponents.DistanceMetric
        |
        +--classifiers.usm.distance.USMDistanceFunction
              |
              +--classifiers.usm.distance.USMStringDistance

All Implemented Interfaces:

java.io.Serializable

public class USMStringDistance

extends USMDistanceFunction

Class to implement Vitanyi's wonderful Universal Similarity Metric (USM) distance function for simple strings! Does exactly what it says on the tin.

Version:

$Version: 1.0$

Author:

David Lindsay (davidl@cs.rhul.ac.uk)

See Also:

Serialized Form

Constructor Summary

USMStringDistance(Instances data)
Simple constructor, just initialise with the data that is being used to check that it is in the correct format!

Method Summary

USMComplexityCache	calculateComplexityAndComplexityStarOf(Instance x, Attribute a) Calculates the first K(x) and second order K(x*) complexities of an object x
double	calculateConcatenatedComplexityOf(Instance x, Instance y, USMComplexityCache usmcc) Calculates the first K(xy*) complexity of an object x with a compressed object y*
boolean	checkInstance(Instance i) Function to check that an individual instance is of the correct format.
boolean	checkInstances(Instances is) Function to check that the data instances are in the correct format.
byte[]	compressBytes(byte[] input) Simple function for compressing an array of bytes into another array of bytes!
static void	main(java.lang.String[] args) Test class for the object!

Methods inherited from class classifiers.usm.distance.USMDistanceFunction

calculateUSM, definePrefix, distance, findAttributesWithPrefix, findInstanceInCache, returnInstanceCache, toString, updateInstanceCache

Methods inherited from class coreComponents.DistanceMetric

forName, reset, updateRanges

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

USMStringDistance

public USMStringDistance(Instances data)

Simple constructor, just initialise with the data that is being used to check that it is in the correct format!

Parameters:

data - the Instance format to be initialised

Method Detail

checkInstances

public boolean checkInstances(Instances is)
                       throws java.lang.Exception

Function to check that the data instances are in the correct format.

Specified by:

checkInstances in class USMDistanceFunction

Parameters:

is - the instances to be checked

Returns:

true if the Instances are in the correct format for this distance function, else false

java.lang.Exception

checkInstance

public boolean checkInstance(Instance i)
                      throws java.lang.Exception

Function to check that an individual instance is of the correct format. This may be a little inefficient with lots of distance calculations.

Specified by:

checkInstance in class USMDistanceFunction

Parameters:

i - the instance to be checked

Returns:

true if the instance has the same fromat as initially set, else false

java.lang.Exception

calculateComplexityAndComplexityStarOf

public USMComplexityCache calculateComplexityAndComplexityStarOf(Instance x,
                                                                 Attribute a)

Calculates the first K(x) and second order K(x*) complexities of an object x

Specified by:

calculateComplexityAndComplexityStarOf in class USMDistanceFunction

Parameters:

x - the instance to calculate the complexities for

Returns:

the complexitys in a paired array [ K(x) , K(x*) ]

calculateConcatenatedComplexityOf

public double calculateConcatenatedComplexityOf(Instance x,
                                                Instance y,
                                                USMComplexityCache usmcc)

Calculates the first K(xy*) complexity of an object x with a compressed object y*

Specified by:

calculateConcatenatedComplexityOf in class USMDistanceFunction

Parameters:

x - the instance to use

y - the instance to use the compression of

Returns:

the complexitys of the concatenated string xy (not with a comma!)

compressBytes

public byte[] compressBytes(byte[] input)

Simple function for compressing an array of bytes into another array of bytes!

Parameters:

input - byte array to be compressed

Returns:

the compressed version of the byte array

main

public static void main(java.lang.String[] args)

Test class for the object!