ec.spatial

Class SpatialTournamentSelection

java.lang.Object

ec.BreedingSource

ec.SelectionMethod

ec.select.TournamentSelection

ec.spatial.SpatialTournamentSelection

All Implemented Interfaces:

Prototype, Setup, SteadyStateBSourceForm, RandomChoiceChooserD, Serializable, Cloneable

public class SpatialTournamentSelection
extends TournamentSelection

A slight modification of the tournament selection procedure for use with spatially-embedded EAs. When selecting an individual, the SpatialTournamentSelection is told a specific individual. It then picks N individuals at random which are within a certain distance (the neighborhood size) of that individual. These individuals then enter a tournament a-la standard Tournament Selection.

The method of picking individuals is either uniform (picking individuals using the Space interface's getRandomIndividual(...)) or random-walk (wandering distance steps at random). You can also stipulate whether the original individual must be in the tournament.

Parameters

base.neighborhood-size int >= 1	(the neighborhood size)
base.ind-competes bool = true or false (default)	(Do we include the base individual in the tournament?)
base.type String: uniform (default) or random-walk	Method for selecting individuals in neighborhood

Further parameters may be found in ec.select.TournamentSelection.

Default Base
spatial.tournament

Version:

2.0

Author:

Liviu Panait and Sean Luke

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
(package private) boolean	indCompetes
(package private) int	neighborhoodSize
static String	P_IND_COMPETES Some models assume an individual is always selected to compete for breeding a child that would take its location in space.
static String	P_N_SIZE The size of the neighborhood from where parents are selected.
static String	P_TYPE Selection procedure.
(package private) int	type
static int	TYPE_RANDOM_WALK
static int	TYPE_UNIFORM
static String	V_RANDOM_WALK
static String	V_UNIFORM

Fields inherited from class ec.select.TournamentSelection

P_PICKWORST, P_SIZE, P_TOURNAMENT, pickWorst, probabilityOfPickingSizePlusOne

Fields inherited from class ec.SelectionMethod

INDS_PRODUCED

Fields inherited from class ec.BreedingSource

NO_PROBABILITY, P_PROB, probability

Constructor Summary

Constructors

Constructor and Description
SpatialTournamentSelection()

Method Summary

Methods

Modifier and Type	Method and Description
Parameter	defaultBase() Returns the default base for this prototype.
int	getRandomIndividual(int number, int subpopulation, EvolutionState state, int thread) Produces the index of a (typically uniformly distributed) randomly chosen individual to fill the tournament.
void	setup(EvolutionState state, Parameter base) Sets up the BreedingPipeline.

Methods inherited from class ec.select.TournamentSelection

betterThan, getTournamentSizeToUse, individualReplaced, produce, sourcesAreProperForm

Methods inherited from class ec.SelectionMethod

finishProducing, prepareToProduce, produce, produces, typicalIndsProduced

Methods inherited from class ec.BreedingSource

clone, getProbability, pickRandom, preparePipeline, setProbability, setupProbabilities

Methods inherited from class java.lang.Object

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

Field Detail

P_N_SIZE

public static final String P_N_SIZE

The size of the neighborhood from where parents are selected. Small neighborhood sizes enforce a local selection pressure, while larger values for this parameters allow further-away individuals to compete for breeding as well.

See Also:

Constant Field Values

neighborhoodSize

int neighborhoodSize

P_IND_COMPETES

public static final String P_IND_COMPETES

Some models assume an individual is always selected to compete for breeding a child that would take its location in space. Other models don't make this assumption. This parameter allows one to specify whether an individual will be selected to compete with others for breeding a child that will take its location in space. If the parameter value is not specified, it is assumed to be false by default.

See Also:

Constant Field Values

indCompetes

boolean indCompetes

P_TYPE

public static final String P_TYPE

Selection procedure.

See Also:

Constant Field Values

V_UNIFORM

public static final String V_UNIFORM

See Also:

Constant Field Values

V_RANDOM_WALK

public static final String V_RANDOM_WALK

See Also:

Constant Field Values

TYPE_UNIFORM

public static final int TYPE_UNIFORM

See Also:

Constant Field Values

TYPE_RANDOM_WALK

public static final int TYPE_RANDOM_WALK

See Also:

Constant Field Values

type

int type

Constructor Detail

SpatialTournamentSelection

public SpatialTournamentSelection()

Method Detail

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 TournamentSelection

See Also:

Prototype.setup(EvolutionState,Parameter)

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(...).

Specified by:

defaultBase in interface Prototype

Overrides:

defaultBase in class TournamentSelection

getRandomIndividual

public int getRandomIndividual(int number,
                      int subpopulation,
                      EvolutionState state,
                      int thread)

Description copied from class: TournamentSelection

Produces the index of a (typically uniformly distributed) randomly chosen individual to fill the tournament. number is the position of the individual in the tournament.

Overrides:

getRandomIndividual in class TournamentSelection