Package ec.select

Class AnnealedSelection

java.lang.Object

ec.BreedingSource

ec.SelectionMethod

ec.select.AnnealedSelection

All Implemented Interfaces:

Prototype, Setup, RandomChoiceChooserD, Serializable, Cloneable

public class AnnealedSelection
extends SelectionMethod

Returns an individual using a form of simulated annealing.

This works as follows. If there is only one individual in the population, he is selected. Otherwise we pick a random individual from among the individuals other than the first individual. If that random individual is fitter than the first individual, it is selected. Otherwise if that random individual is as fit as the first individual, one of the two is selected at random. Otherwise if the random individual is not as fit as the first individual, it is selected with a probability P = e^((fit(random ind) - fit(first ind)) / t), where t is a TEMPERATURE. Otherwise the first individual is selected.

The temperature starts at a high value >> 0, and is slowly cut down by multiplying it by a CUTDOWN value every generation. When the temperature reaches 0, then the first individual is selected every time.

The selected individual can be cached so the same individual is returned multiple times without being recomputed. This cache is cleared after prepareToProduce(...) is called. Note that this option is not appropriate for Steady State Evolution, which only calls prepareToProduce(...) once.

Typical Number of Individuals Produced Per produce(...) call
Always 1.

Parameters

base.cache bool = true or false (default)	(should we cache the individual?)
base.temperature double > 0 (or undefined)	(annealing start temperature)
base.cutdown 0.0 <= double >= 1.0 (default is 0.95)	(annealing cutdown)

Default Base
select.annealed

See Also:

• Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static final String	P_ANNEALED	Default base
static final String	P_CACHE
static final String	P_CUTDOWN
static final String	P_TEMPERATURE
static final double	V_CUTDOWN

Fields inherited from class ec.SelectionMethod

INDS_PRODUCED, KEY_PARENTS

Fields inherited from class ec.BreedingSource

NO_PROBABILITY, P_PROB, probability

Constructor Summary

Constructors

Constructor	Description
AnnealedSelection()

Method Summary

Modifier and Type	Method	Description
void	cacheBest(int subpopulation, EvolutionState state, int thread)
Parameter	defaultBase()	Returns the default base for this prototype.
void	prepareToProduce(EvolutionState s, int subpopulation, int thread)	A default version of prepareToProduce which does nothing.
int	produce(int subpopulation, EvolutionState state, int thread)	An alternative form of "produce" special to Selection Methods; selects an individual from the given subpopulation and returns its position in that subpopulation.
void	setup(EvolutionState state, Parameter base)	Sets up the BreedingPipeline.

Methods inherited from class ec.SelectionMethod

finishProducing, produce, produces, produceWithoutCloning, typicalIndsProduced

Methods inherited from class ec.BreedingSource

clone, fillStubs, getProbability, pickRandom, preparePipeline, setProbability, setupProbabilities

Methods inherited from class java.lang.Object

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

Field Details

P_ANNEALED

public static final String P_ANNEALED

Default base

See Also:

• Constant Field Values

P_CACHE

public static final String P_CACHE

See Also:

• Constant Field Values

P_TEMPERATURE

public static final String P_TEMPERATURE

See Also:

• Constant Field Values

P_CUTDOWN

public static final String P_CUTDOWN

See Also:

• Constant Field Values

V_CUTDOWN

public static final double V_CUTDOWN

See Also:

• Constant Field Values

Constructor Details

AnnealedSelection

public AnnealedSelection()

Method Details

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(...).

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 BreedingSource

See Also:

• Prototype.setup(EvolutionState,Parameter)

prepareToProduce

public void prepareToProduce(EvolutionState s,
 int subpopulation,
 int thread)

Description copied from class: SelectionMethod

A default version of prepareToProduce which does nothing.

Overrides:

prepareToProduce in class SelectionMethod

cacheBest

public void cacheBest(int subpopulation,
 EvolutionState state,
 int thread)

produce

public int produce(int subpopulation,
 EvolutionState state,
 int thread)

Description copied from class: SelectionMethod

An alternative form of "produce" special to Selection Methods; selects an individual from the given subpopulation and returns its position in that subpopulation.

Specified by:

produce in class SelectionMethod