org.dllearner.algorithms.ocel

Class FlexibleHeuristic

java.lang.Object

org.dllearner.algorithms.ocel.FlexibleHeuristic

All Implemented Interfaces:

Comparator<ExampleBasedNode>, ExampleBasedHeuristic, Component, Heuristic<ExampleBasedNode>

public class FlexibleHeuristic
extends Object
implements ExampleBasedHeuristic

This heuristic compares two nodes by computing a score using the number of covered negatives and the horizontal expansion factor of a node as input. Using this score it decides which one of the nodes seems to be more promising. The heuristic is flexible, because it offers a tradeoff between accurary and horizontal expansion (concept length). In contrast to the lexicographic heuristic this means that it sometimes prefers worse classifiers with low horizontal expansion over a better classifier with high horizontal expansion. It can be configured by using the "percentPerLenghtUnit" constructor argument. A higher value means that the algorithm is more likely to search in unexplored areas (= low horizontal expansion) of the search space vs. looking in promising but already explored (= high horizontal expansion) areas of the search space.

Author:

Jens Lehmann

Constructor Summary

Constructors

Constructor and Description
FlexibleHeuristic()
FlexibleHeuristic(int nrOfNegativeExamples, double percentPerLengthUnit)

Method Summary

Modifier and Type	Method and Description
int	compare(ExampleBasedNode n1, ExampleBasedNode n2)
boolean	equals(Object o)
double	getNodeScore(ExampleBasedNode n1)
int	getNrOfNegativeExamples()
double	getPercentPerLengthUnit()
void	init() Method to be called after the component has been configured.
void	setNrOfNegativeExamples(int nrOfNegativeExamples)
void	setPercentPerLengthUnit(double percentPerLengthUnit)

Methods inherited from class java.lang.Object

getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Comparator

comparing, comparing, comparingDouble, comparingInt, comparingLong, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Constructor Detail

FlexibleHeuristic

public FlexibleHeuristic(int nrOfNegativeExamples,
                         double percentPerLengthUnit)

FlexibleHeuristic

public FlexibleHeuristic()

Method Detail

getNrOfNegativeExamples

public int getNrOfNegativeExamples()

setNrOfNegativeExamples

public void setNrOfNegativeExamples(int nrOfNegativeExamples)

getPercentPerLengthUnit

public double getPercentPerLengthUnit()

setPercentPerLengthUnit

public void setPercentPerLengthUnit(double percentPerLengthUnit)

compare

public int compare(ExampleBasedNode n1,
                   ExampleBasedNode n2)

Specified by:

compare in interface Comparator<ExampleBasedNode>

equals

public boolean equals(Object o)

Specified by:

equals in interface Comparator<ExampleBasedNode>

Overrides:

equals in class Object

init

public void init()
          throws ComponentInitException

Description copied from interface: Component

Method to be called after the component has been configured. Implementation of components can overwrite this method to perform setup and initialisation tasks for this component.

Specified by:

init in interface Component

Throws:

ComponentInitException - This exception is thrown if any exceptions occur within the initialisation process of this component. As component developer, you are encouraged to re-throw occurring exception as ComponentInitException and giving an error message as well as the actually exception by using the constructor ComponentInitException(String, Throwable).

getNodeScore

public double getNodeScore(ExampleBasedNode n1)

Specified by:

getNodeScore in interface Heuristic<ExampleBasedNode>