ec.select

Class BoltzmannSelection

java.lang.Object

ec.BreedingSource

ec.SelectionMethod

ec.select.FitProportionateSelection

ec.select.BoltzmannSelection

All Implemented Interfaces:

Prototype, Setup, RandomChoiceChooserD, Serializable, Cloneable

public class BoltzmannSelection
extends FitProportionateSelection

Similar to FitProportionateSelection, but with a Simulated Annealing style twist. BoltzmannSelection picks individuals of a population in proportion to an adjusted version of their fitnesses instead of their actual fitnesses as returned by fitness(). The adjusted fitness is calculated by e^(fitness/current_temperature) where current_temperature is a temperature value that decreases by a constant cooling rate as generations of evolution pass. The current_temperature is calculated by starting-temperature - (cooling-rate * the_current_generation_number). When the temperature dips below 1.0, annealing ceases and BoltzmannSelection reverts to normal FitProportionateSelection behavior.

Like FitProportionateSelection this is not appropriate for steady-state evolution. If you're not familiar with the relative advantages of selection methods and just want a good one, use TournamentSelection instead. Not appropriate for multiobjective fitnesses.

Note: Fitnesses must be non-negative. 0 is assumed to be the worst fitness.

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

Parameters

base.starting-temperature double = some large number (defaults to 1.0)	(the starting temperature for our simulated annealing style adjusted fitness proportions)
base.cooling-rate double = some smaller number (defaults to 0.0 which causes BoltzmannSelection to behave just as FitProportionateSelection would)	(how slow, or fast, do you want to cool the annealing fitness proportions?)

Default Base
select.boltzmann

Version:

1.0

Author:

Jack Compton

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private double	coolingRate Cooling rate
static String	P_BOLTZMANN Default base
static String	P_COOLING_RATE Cooling rate parameter
static String	P_STARTING_TEMPERATURE Starting temperature parameter
private double	startingTemperature Starting temperature

Fields inherited from class ec.select.FitProportionateSelection

fitnesses, P_FITNESSPROPORTIONATE

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
BoltzmannSelection()

Method Summary

Methods

Modifier and Type	Method and Description
(package private) double	boltzmannExpectedValue(double fitness, EvolutionState s)
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.
void	setup(EvolutionState state, Parameter base) Sets up the BreedingPipeline.

Methods inherited from class ec.select.FitProportionateSelection

finishProducing, produce

Methods inherited from class ec.SelectionMethod

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_BOLTZMANN

public static final String P_BOLTZMANN

Default base

See Also:

Constant Field Values

P_STARTING_TEMPERATURE

public static final String P_STARTING_TEMPERATURE

Starting temperature parameter

See Also:

Constant Field Values

P_COOLING_RATE

public static final String P_COOLING_RATE

Cooling rate parameter

See Also:

Constant Field Values

startingTemperature

private double startingTemperature

Starting temperature

coolingRate

private double coolingRate

Cooling rate

Constructor Detail

BoltzmannSelection

public BoltzmannSelection()

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(...).

Specified by:

defaultBase in interface Prototype

Overrides:

defaultBase in class FitProportionateSelection

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 FitProportionateSelection

boltzmannExpectedValue

double boltzmannExpectedValue(double fitness,
                            EvolutionState s)