ec.select
Class BoltzmannSelection

java.lang.Object
  extended by ec.BreedingSource
      extended by ec.SelectionMethod
          extended by ec.select.FitProportionateSelection
              extended by ec.select.BoltzmannSelection
All Implemented Interfaces:
Prototype, Setup, RandomChoiceChooser, java.io.Serializable, java.lang.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

See Also:
Serialized Form

Field Summary
static java.lang.String P_BOLTZMANN
          Default base
static java.lang.String P_COOLING_RATE
          Cooling rate parameter
static java.lang.String P_STARTING_TEMPERATURE
          Starting temperature parameter
 
Fields inherited from class ec.select.FitProportionateSelection
fitnesses, P_FITNESSPROPORTIONATE
 
Fields inherited from class ec.SelectionMethod
INDS_PRODUCED
 
Fields inherited from class ec.BreedingSource
CHECKBOUNDARY, DEFAULT_PRODUCED, NO_PROBABILITY, P_PROB, probability, UNUSED
 
Constructor Summary
BoltzmannSelection()
           
 
Method Summary
 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
preparePipeline, produce, produces, typicalIndsProduced
 
Methods inherited from class ec.BreedingSource
clone, getProbability, pickRandom, 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 java.lang.String P_BOLTZMANN
Default base

See Also:
Constant Field Values

P_STARTING_TEMPERATURE

public static final java.lang.String P_STARTING_TEMPERATURE
Starting temperature parameter

See Also:
Constant Field Values

P_COOLING_RATE

public static final java.lang.String P_COOLING_RATE
Cooling rate parameter

See Also:
Constant Field Values
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