Package ec.simple

Class SimpleFitness

java.lang.Object
ec.Fitness
ec.simple.SimpleFitness
All Implemented Interfaces:
Prototype, Setup, Serializable, Cloneable, Comparable<Object>
Direct Known Subclasses:
DOVSFitness
public class SimpleFitness extends Fitness
A simple default fitness, consisting of a double floating-point value where fitness A is superior to fitness B if and only if A > B. Fitness values may range from (-infinity,infinity) exclusive -- that is, you may not have infinite fitnesses.

Some kinds of selection methods require a more stringent definition of fitness. For example, FitProportionateSelection requires that fitnesses be non-negative (since it must place them into a proportionate distribution). You may wish to restrict yourself to values in [0,1] or [0,infinity) in such cases.

Default Base
simple.fitness

See Also:

  • Field Details

    • isIdeal

      protected boolean isIdeal

  • Constructor Details

    • SimpleFitness

      public SimpleFitness()

  • 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(...).

    • setFitness

      public void setFitness(EvolutionState state, double _f)
      Deprecated -- now redefined to set the fitness but ALWAYS say that it's not ideal. If you need to specify that it's ideal, you should use the new function setFitness(final EvolutionState state, double _f, boolean _isIdeal).

    • setFitness

      public void setFitness(EvolutionState state, double _f, boolean _isIdeal)

    • fitness

      public double fitness()
      Description copied from class: Fitness
      Should return an absolute fitness value ranging from negative infinity to infinity, NOT inclusive (thus infinity, negative infinity, and NaN are NOT valid fitness values). This should be interpreted as: negative infinity is worse than the WORST possible fitness, and positive infinity is better than the IDEAL fitness.

      You are free to restrict this range any way you like: for example, your fitness values might fall in the range [-5.32, 2.3]

      Selection methods relying on fitness proportionate information will assume the fitness is non-negative and should throw an error if it is not. Thus if you plan on using FitProportionateSelection, BestSelection, or GreedyOverselection, for example, your fitnesses should assume that 0 is the worst fitness and positive fitness are better. If you're using other selection methods (Tournament selection, various ES selection procedures, etc.) your fitness values can be anything.

      Similarly, if you're writing a selection method and it needs positive fitnesses, you should check for negative values and issue an error; and if your selection method doesn't need an absolute fitness value, it should use the equivalentTo() and betterThan() methods instead.

      If your fitness scheme does not use a metric quantifiable to a single positive value (for example, MultiObjectiveFitness), you should perform some reasonable translation.

      Specified by:
      fitness in class Fitness

    • setup

      public void setup(EvolutionState state, Parameter base)
      Description copied from interface: Prototype
      Sets up the object by reading it from the parameters stored in state, built off of the parameter base base. If an ancestor implements this method, be sure to call super.setup(state,base); before you do anything else.

      For prototypes, setup(...) is typically called once for the prototype instance; cloned instances do not receive the setup(...) call. setup(...) may be called more than once; the only guarantee is that it will get called at least once on an instance or some "parent" object from which it was ultimately cloned.

      Specified by:
      setup in interface Prototype
      Specified by:
      setup in interface Setup
      Overrides:
      setup in class Fitness

    • isIdealFitness

      public boolean isIdealFitness()
      Description copied from class: Fitness
      Should return true if this is a good enough fitness to end the run
      Specified by:
      isIdealFitness in class Fitness

    • equivalentTo

      public boolean equivalentTo(Fitness _fitness)
      Description copied from class: Fitness
      Should return true if this fitness is in the same equivalence class as _fitness, that is, neither is clearly better or worse than the other. You may assume that _fitness is of the same class as yourself. For any two fitnesses fit1 and fit2 of the same class, it must be the case that fit1.equivalentTo(fit2) == fit2.equivalentTo(fit1), and that only one of fit1.betterThan(fit2), fit1.equivalentTo(fit2), and fit2.betterThan(fit1) can be true.
      Specified by:
      equivalentTo in class Fitness

    • betterThan

      public boolean betterThan(Fitness _fitness)
      Description copied from class: Fitness
      Should return true if this fitness is clearly better than _fitness; You may assume that _fitness is of the same class as yourself. For any two fitnesses fit1 and fit2 of the same class, it must be the case that fit1.equivalentTo(fit2) == fit2.equivalentTo(fit1), and that only one of fit1.betterThan(fit2), fit1.equivalentTo(fit2), and fit2.betterThan(fit1) can be true.
      Specified by:
      betterThan in class Fitness

    • fitnessToString

      public String fitnessToString()
      Description copied from class: Fitness
      Print to a string the fitness in a fashion intended to be parsed in again via readFitness(...). The fitness and evaluated flag should not be included. The default form simply calls toString(), which is almost certainly wrong, and you'll probably want to override this to something else. When overriding, you may wish to check to see if the 'trials' variable is non-null, and issue an error if so.
      Overrides:
      fitnessToString in class Fitness

    • fitnessToStringForHumans

      public String fitnessToStringForHumans()
      Description copied from class: Fitness
      Print to a string the fitness in a fashion readable by humans, and not intended to be parsed in again. The default form simply calls toString(), but you'll probably want to override this to something else.
      Overrides:
      fitnessToStringForHumans in class Fitness

    • readFitness

      public void readFitness(EvolutionState state, LineNumberReader reader) throws IOException
      Presently does not decode the fact that the fitness is ideal or not
      Overrides:
      readFitness in class Fitness
      Throws:
      IOException

    • writeFitness

      public void writeFitness(EvolutionState state, DataOutput dataOutput) throws IOException
      Description copied from class: Fitness
      Writes the binary form of an individual out to a DataOutput. This is not for serialization: the object should only write out the data relevant to the object sufficient to rebuild it from a DataInput. The default version exits the program with an "unimplemented" error; you should override this, and be certain to also write the 'trials' variable as well.
      Overrides:
      writeFitness in class Fitness
      Throws:
      IOException

    • readFitness

      public void readFitness(EvolutionState state, DataInput dataInput) throws IOException
      Description copied from class: Fitness
      Reads the binary form of an individual from a DataInput. This is not for serialization: the object should only read in the data written out via printIndividual(state,dataInput). The default version exits the program with an "unimplemented" error; you should override this, and be certain to also write the 'trials' variable as well.
      Overrides:
      readFitness in class Fitness
      Throws:
      IOException

    • setToMeanOf

      public void setToMeanOf(EvolutionState state, Fitness[] fitnesses)
      Description copied from class: Fitness
      Sets the fitness to be the same value as the mean of the provided fitnesses. The default version of this method exits with an "unimplemented" error; you should override this.
      Overrides:
      setToMeanOf in class Fitness