jcgp.backend.modules.problem

Class TravellingSalesmanProblem

java.lang.Object

jcgp.backend.modules.Module

jcgp.backend.modules.problem.Problem

jcgp.backend.modules.problem.TravellingSalesmanProblem

public class TravellingSalesmanProblem
extends Problem

Travelling salesman problem

Using this problem type, travelling salesman tours can be evolved. parseData() must be used to load the desired city coordinates in the standard .tsp format.

Author:

Eduardo Pedroni

See Also:

TravellingSalesmanFunctions

Constructor Summary

Constructors

Constructor and Description
TravellingSalesmanProblem(Resources resources) Construct a new instance of TravellingSalesmanProblem.

Method Summary

Modifier and Type	Method and Description
void	evaluate(Population population, Resources resources) The most important method of the problem type.
boolean	isImprovement(Chromosome fittest) Used to assert whether a given chromosome is an improvement over the current best chromosome.
boolean	isPerfectSolution(Chromosome fittest) Used to assert whether a given chromosome is a perfect solution to the problem.
void	parseProblemData(java.io.File file, ModifiableResources resources) Parses the specified file and uses the parsed data to set up the problem type instance appropriately.

Methods inherited from class jcgp.backend.modules.problem.Problem

getBestFitness, getFileExtension, getFunctionSet, reset

Methods inherited from class jcgp.backend.modules.Module

getLocalParameters, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

TravellingSalesmanProblem

public TravellingSalesmanProblem(Resources resources)

Construct a new instance of TravellingSalesmanProblem.

Parameters:

resources - a reference to the experiment's resources.

Method Detail

evaluate

public void evaluate(Population population,
                     Resources resources)

Description copied from class: Problem

The most important method of the problem type. This is called once per generation, when the new population has been generated.

The basic functionality of this method is to loop through all chromosomes in the population and decode them according to the problem type. The fitness of each chromosome is then calculated using the problem data or otherwise (subjective problem types such as art generation might leave fitness evaluations up to the user) and assigned to the appropriate chromosome.

In addition, realisations of this method should update the value of bestFitness as appropriate, since the value of this parameter is displayed if a GUI is in use.

Specified by:

evaluate in class Problem

Parameters:

population - the population to be evaluated.

resources - parameters and utilities for optional reference.

isPerfectSolution

public boolean isPerfectSolution(Chromosome fittest)

Description copied from class: Problem

Used to assert whether a given chromosome is a perfect solution to the problem. It is up to the problem to define what qualifies a perfect solution, as some problems (subject ones such as music and art evolution, for example) might not have perfect solutions at all.

Note that if this method returns true, the experiment will move on to the next run, or finish if no more runs are left.

Specified by:

isPerfectSolution in class Problem

Parameters:

fittest - the potentially perfect chromosome.

Returns:

true if the argument is a perfect solution.

parseProblemData

public void parseProblemData(java.io.File file,
                             ModifiableResources resources)

Description copied from class: Problem

Parses the specified file and uses the parsed data to set up the problem type instance appropriately. Any necessary resource changes can be performed using the provided ModifiableResources instance.

In addition, realisations of this method should update the value of maxFitness where appropriate, as this may be displayed to the user if a GUI is in use.

Specified by:

parseProblemData in class Problem

Parameters:

file - the data file to parse.

resources - a modifiable reference to the experiment's resources.

isImprovement

public boolean isImprovement(Chromosome fittest)

Description copied from class: Problem

Used to assert whether a given chromosome is an improvement over the current best chromosome. A typical implementation of this method will simply compare chromosome fitness values, though the problem type is free to implement this in any way.

Specified by:

isImprovement in class Problem

Parameters:

fittest - the potentially fitter chromosome.

Returns:

true if the argument is fitter than the currently fittest chromosome.