ec.gp.breed

Class MutatePromotePipeline

java.lang.Object

ec.BreedingSource

ec.BreedingPipeline

ec.gp.GPBreedingPipeline

ec.gp.breed.MutatePromotePipeline

All Implemented Interfaces:

Prototype, Setup, SteadyStateBSourceForm, RandomChoiceChooserD, Serializable, Cloneable

public class MutatePromotePipeline
extends GPBreedingPipeline

MutatePromotePipeline works very similarly to the PromoteNode algorithm described in Kumar Chellapilla, "A Preliminary Investigation into Evolving Modular Programs without Subtree Crossover", GP98, and is also similar to the "deletion" operator found in Una-May O'Reilly's thesis, "An Analysis of Genetic Programming".

MutatePromotePipeline tries tries times to find a tree that has at least one promotable node. It then picks randomly from all the promotable nodes in the tree, and promotes one. If it cannot find a valid tree in tries times, it gives up and simply copies the individual.

"Promotion" means to take a node n whose parent is m, and replacing the subtree rooted at m with the subtree rooted at n.

A "Promotable" node means a node which is capable of promotion given the existing type constraints. In general to promote a node foo, foo must have a parent node, and must be type-compatible with the child slot that its parent fills.

Typical Number of Individuals Produced Per produce(...) call
...as many as the source produces

Number of Sources
1

Parameters

base.tries int >= 1	(number of times to try finding valid pairs of nodes)
base.tree.0 0 < int < (num trees in individuals), if exists	(tree chosen for mutation; if parameter doesn't exist, tree is picked at random)

Default Base
gp.breed.mutate-promote

Version:

1.0

Author:

Sean Luke

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	NUM_SOURCES
(package private) int	numTries The number of times the pipeline tries to build a valid mutated tree before it gives up and just passes on the original
static String	P_MUTATEPROMOTE
static String	P_NUM_TRIES
private GPNode	promotableNode
(package private) int	tree Is our tree fixed? If not, this is -1

Fields inherited from class ec.gp.GPBreedingPipeline

P_NODESELECTOR, P_TREE, TREE_UNFIXED

Fields inherited from class ec.BreedingPipeline

DYNAMIC_SOURCES, likelihood, mybase, P_LIKELIHOOD, P_NUMSOURCES, P_SOURCE, sources, V_SAME

Fields inherited from class ec.BreedingSource

NO_PROBABILITY, P_PROB, probability

Constructor Summary

Constructors

Constructor and Description
MutatePromotePipeline()

Method Summary

Methods

Modifier and Type	Method and Description
Parameter	defaultBase() Returns the default base for this prototype.
private int	numPromotableNodes(GPInitializer initializer, GPNode root, int soFar)
int	numSources() Returns the number of sources to this pipeline.
private int	pickPromotableNode(GPInitializer initializer, GPNode root, int num)
int	produce(int min, int max, int start, int subpopulation, Individual[] inds, EvolutionState state, int thread) Produces n individuals from the given subpopulation and puts them into inds[start...start+n-1], where n = Min(Max(q,min),max), where q is the "typical" number of individuals the BreedingSource produces in one shot, and returns n.
private boolean	promotable(GPInitializer initializer, GPNode node)
private void	promoteSomething(GPNode node)
void	setup(EvolutionState state, Parameter base) Sets up the BreedingPipeline.

Methods inherited from class ec.gp.GPBreedingPipeline

produces

Methods inherited from class ec.BreedingPipeline

clone, finishProducing, individualReplaced, maxChildProduction, minChildProduction, preparePipeline, prepareToProduce, reproduce, sourcesAreProperForm, typicalIndsProduced

Methods inherited from class ec.BreedingSource

getProbability, pickRandom, setProbability, setupProbabilities

Methods inherited from class java.lang.Object

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

Field Detail

P_MUTATEPROMOTE

public static final String P_MUTATEPROMOTE

See Also:

Constant Field Values

P_NUM_TRIES

public static final String P_NUM_TRIES

See Also:

Constant Field Values

NUM_SOURCES

public static final int NUM_SOURCES

See Also:

Constant Field Values

tree

int tree

Is our tree fixed? If not, this is -1

numTries

int numTries

The number of times the pipeline tries to build a valid mutated tree before it gives up and just passes on the original

promotableNode

private GPNode promotableNode

Constructor Detail

MutatePromotePipeline

public MutatePromotePipeline()

Method Detail

defaultBase

public Parameter defaultBase()

Description copied from interface: Prototype

Returns the default base for this prototype. This should generally be implemented by building off of the static base() method on the DefaultsForm object for the prototype's package. This should be callable during setup(...).

numSources

public int numSources()

Description copied from class: BreedingPipeline

Returns the number of sources to this pipeline. Called during BreedingPipeline's setup. Be sure to return a value > 0, or DYNAMIC_SOURCES which indicates that setup should check the parameter file for the parameter "num-sources" to make its determination.

Specified by:

numSources in class BreedingPipeline

setup

public void setup(EvolutionState state,
         Parameter base)

Description copied from class: BreedingSource

Sets up the BreedingPipeline. You can use state.output.error here because the top-level caller promises to call exitIfErrors() after calling setup. Note that probability might get modified again by an external source if it doesn't normalize right.

The most common modification is to normalize it with some other set of probabilities, then set all of them up in increasing summation; this allows the use of the fast static BreedingSource-picking utility method, BreedingSource.pickRandom(...). In order to use this method, for example, if four breeding source probabilities are {0.3, 0.2, 0.1, 0.4}, then they should get normalized and summed by the outside owners as: {0.3, 0.5, 0.6, 1.0}.

Specified by:

setup in interface Prototype

Specified by:

setup in interface Setup

Overrides:

setup in class BreedingPipeline

See Also:

Prototype.setup(EvolutionState,Parameter)

promotable

private boolean promotable(GPInitializer initializer,
                 GPNode node)

promoteSomething

private void promoteSomething(GPNode node)

numPromotableNodes

private int numPromotableNodes(GPInitializer initializer,
                     GPNode root,
                     int soFar)

pickPromotableNode

private int pickPromotableNode(GPInitializer initializer,
                     GPNode root,
                     int num)

produce

public int produce(int min,
          int max,
          int start,
          int subpopulation,
          Individual[] inds,
          EvolutionState state,
          int thread)

Description copied from class: BreedingSource

Produces n individuals from the given subpopulation and puts them into inds[start...start+n-1], where n = Min(Max(q,min),max), where q is the "typical" number of individuals the BreedingSource produces in one shot, and returns n. max must be >= min, and min must be >= 1. For example, crossover might typically produce two individuals, tournament selection might typically produce a single individual, etc.

Specified by:

produce in class BreedingSource