evSOLve.JEvolution.gp

Class TreeChromosome

java.lang.Object

evSOLve.JEvolution.chromosomes.Chromosome

evSOLve.JEvolution.gp.TreeChromosome

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

public class TreeChromosome
extends Chromosome

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	FULL
static int	GROW Initial mode of creation of Chromosome.
static int	RAMPED

Fields inherited from class evSOLve.JEvolution.chromosomes.Chromosome

BIASED, crossoverPoints, crossoverRate, LAPLACE, length, mutationRate, soupType

Constructor Summary

Constructors

Constructor and Description
TreeChromosome(Element c) Creates a TreeChromosome via XML.
TreeChromosome(int depth, int resultType) Constructs a TreeChromosome.

Method Summary

Methods

Modifier and Type	Method and Description
void	addNode(ProgramNode node) Adds a program node to the node set.
TreeChromosome	clone() A deep clone of this TreeChromosome.
void	doCrossover(Chromosome father) Performs crossover by selecting a random node in each of the two parent trees and swapping the subtrees.
void	doMutation() Performs tree and node mutation by iterating over the tree.
boolean	equals(java.lang.Object chrom) Compares this program tree to another in 'chrom'.
void	fromString(java.lang.String b) Creates a program tree from its string representation.
java.lang.Object	getBases() Returns the genotype aka the program tree, which in this case is also the phenotype.
boolean	getNodeMutation() Returns the flag for node mutation.
int	hashCode() Returns a hash code for the program tree.
void	mixSoup() Creates a random program tree in different manners.
void	setNodeMutation(boolean nodeMutation) Sets the flag for node mutation.
java.lang.String	toString() Returns the string representation of the program tree.
Element	toXml(Element parent) Saves the current state to XML.

Methods inherited from class evSOLve.JEvolution.chromosomes.Chromosome

create, getCrossoverPoints, getCrossoverRate, getLength, getMutationRate, getSoupType, setCrossoverPoints, setCrossoverRate, setLength, setMutationRate, setSoupType

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

GROW

public static final int GROW

Initial mode of creation of Chromosome.

See Also:

Constant Field Values

RAMPED

public static final int RAMPED

See Also:

Constant Field Values

FULL

public static final int FULL

See Also:

Constant Field Values

Constructor Detail

TreeChromosome

public TreeChromosome(int depth,
              int resultType)

Constructs a TreeChromosome.

Parameters:

depth - the maximal depth of the initial program tree

resultType - the type of the result of the evolved function/program

TreeChromosome

public TreeChromosome(Element c)

Creates a TreeChromosome via XML.

Parameters:

c - an XML Chromosome element

Method Detail

clone

public TreeChromosome clone()

A deep clone of this TreeChromosome.

Overrides:

clone in class Chromosome

Returns:

a deep clone

equals

public boolean equals(java.lang.Object chrom)

Compares this program tree to another in 'chrom'.

Specified by:

equals in class Chromosome

Parameters:

chrom - a TreeChromosome

Returns:

true, if the trees are equal

hashCode

public int hashCode()

Returns a hash code for the program tree.

Specified by:

hashCode in class Chromosome

Returns:

a hash code

getBases

public java.lang.Object getBases()

Returns the genotype aka the program tree, which in this case is also the phenotype.

Specified by:

getBases in class Chromosome

Returns:

the program tree

addNode

public void addNode(ProgramNode node)

Adds a program node to the node set.

Parameters:

node - a program node

getNodeMutation

public boolean getNodeMutation()

Returns the flag for node mutation.

Returns:

true, if node mutation is on

setNodeMutation

public void setNodeMutation(boolean nodeMutation)

Sets the flag for node mutation.

Parameters:

nodeMutation - true, if node mutation on

doMutation

public void doMutation()

Performs tree and node mutation by iterating over the tree. Either tree mutation or node mutation is performed depending on 'nodeMutation'.

Specified by:

doMutation in class Chromosome

doCrossover

public void doCrossover(Chromosome father)

Performs crossover by selecting a random node in each of the two parent trees and swapping the subtrees. If the result types of the two nodes do not match, the mother index (node) is fixed, and the father index is increased in order to find a matching subtree. If the father tree contains no matching node, the crossover does not take place. Note that we only check father indices greater than the random father node (we could also make the search complete by searching all tree nodes).

Specified by:

doCrossover in class Chromosome

Parameters:

father - the father chromosome

mixSoup

public void mixSoup()

Creates a random program tree in different manners. FULL always creates trees with the given 'lengt' (=depth), GROW may stop growing at any level with a probability of 0.5, and RAMPED is in the spirit of the original GP ramp, but is here a probabilistic ramping, so trees of any size may be generated. The limit size for all trees is 'length' (=depth).

Specified by:

mixSoup in class Chromosome

toString

public java.lang.String toString()

Returns the string representation of the program tree.

Specified by:

toString in class Chromosome

Returns:

the tree in string form

fromString

public void fromString(java.lang.String b)

Creates a program tree from its string representation. Does nothing here, as in the case of GP the program tree is not created from its string representation, but from the XML element 'Tree'. However, the string representation is still saved with the XML element 'Bases'.

Specified by:

fromString in class Chromosome

Parameters:

b - the program tree in string form

toXml

public Element toXml(Element parent)

Saves the current state to XML.

Overrides:

toXml in class Chromosome

Parameters:

parent - the JDOM parent element

Returns:

the Chromosome element with NodeSet and Tree