com.epochx.core
Class GPMutation<TYPE>

java.lang.Object
  com.epochx.core.GPMutation<TYPE>

All Implemented Interfaces:

GenerationListener

public class GPMutation<TYPE>
extends java.lang.Object
implements GenerationListener

This class performs the very simple task of linking together individual selection and mutation. The actual tasks of crossover and selection are performed by Mutation and ProgramSelector implementations respectively.

See Also:

Mutation, PointMutation, SubtreeMutation, ProgramSelector

Constructor Summary

GPMutation(GPModel<TYPE> model)
Constructs an instance of GPMutation which will setup the mutation operation.

Method Summary

int	getRevertedCount() After a mutation is made, the controlling model is requested to confirm the mutation by a call to acceptMutation().
CandidateProgram<TYPE>	mutate() Selects a CandidateProgram from the population using the ProgramSelector returned by a call to getProgramSelector() on the model given at construction and submits it to the Mutation operator which is obtained by calling getMutation() on the model.
void	onGenerationStart() Called after each generation.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GPMutation

public GPMutation(GPModel<TYPE> model)

Constructs an instance of GPMutation which will setup the mutation operation. Note that the actual mutation operation will be performed by the subclass of Mutation returned by the models getMutation() method.

Parameters:

model - the GPModel which defines the Mutation operator and ProgramSelector to use to perform one act of mutation on an individual in the population.

See Also:

Mutation

Method Detail

mutate

public CandidateProgram<TYPE> mutate()

Selects a CandidateProgram from the population using the ProgramSelector returned by a call to getProgramSelector() on the model given at construction and submits it to the Mutation operator which is obtained by calling getMutation() on the model.

After a mutation is made, the controlling model is requested to confirm the mutation by a call to acceptMutation(). This gives the model total control over whether a mutation is allowed to proceed. If acceptMutation() returns false then the new CandidateProgram is discarded and a new individual is selected and attempted for mutation. The number of times the mutation was reverted before being accepted is available through a call to getRevertedCount().

Even after a mutation has been accepted by the model, it may still be prevented from proceeding if the program depth of the new program exceeds the max depth that the model defines. In the case that it does exceed the limit then the original program is returned as the result. This does not count towards the number of reversions.

Returns:

a CandidateProgram generated through mutation by the Mutation operator in use, or if the max depth limit was exceeded then the original selected program before mutation will be returned.

getRevertedCount

public int getRevertedCount()

After a mutation is made, the controlling model is requested to confirm the mutation by a call to acceptMutation(). This gives the model total control over whether a mutation is allowed to proceed. If acceptMutation() returns false then the mutated program is discarded and a new CandidateProgram selected to undergo mutation. The number of times the mutation was reverted before being accepted is available through a call to this method.

Returns:

the number of times the mutation was rejected by the model.

onGenerationStart

public void onGenerationStart()

Called after each generation. For each generation we should reset all parameters taken from the model incase they've changed. The generation event is then CONFIRMed.

Specified by:

onGenerationStart in interface GenerationListener