Package ec.gp.ge

Class GEProblem

java.lang.Object
ec.Problem
ec.gp.ge.GEProblem
All Implemented Interfaces:
GroupedProblemForm, Prototype, Setup, SimpleProblemForm, Serializable, Cloneable
public class GEProblem extends Problem implements SimpleProblemForm, GroupedProblemForm
GEProblem is a special replacement for Problem which performs GE mapping. You do not subclass from GEProblem. Rather, create a GPProblem subclass and set it to be the 'problem' parameter of the GEProblem. The GEProblem will convert the GEIndividual into a GPIndividual, then pass this GPIndividual to the GPProblem to be evaluated.

The procedure is as follows. Let's say your GPProblem is the Artificial Ant problem. Instead of saying...

eval.problem = ec.app.ant.Ant
eval.problem = ec.app.ant.Ant
eval.problem.data = ec.app.ant.AntData
eval.problem.moves = 400
eval.problem.file = santafe.trl

... you instead make your problem a GEProblem like this:

eval.problem = ec.gp.ge.GEProblem

... and then you hang the Ant problem, and all its subsidiary data, as the 'problem' parameter from the GEProblem like so:

eval.problem.problem = ec.app.ant.Ant
eval.problem.problem.data = ec.app.ant.AntData
eval.problem.problem.moves = 400
eval.problem.problem.file = santafe.trl

Everything else should be handled for you. GEProblem is also compatible with the MasterProblem procedure for distributed evaluation, and is also both a SimpleProblemForm and a GroupedProblemForm. We've got you covered.

Parameters

base.problem
classname, inherits from GPProblem		 (The GPProblem which actually performs the evaluation of the mapped GPIndividual)
See Also:

  • Field Details

  • Constructor Details

    • GEProblem

      public GEProblem()

  • Method Details

    • 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 Problem

    • clone

      public Object clone()
      Description copied from interface: Prototype
      Creates a new individual cloned from a prototype, and suitable to begin use in its own evolutionary context.

      Typically this should be a full "deep" clone. However, you may share certain elements with other objects rather than clone hem, depending on the situation:

      • If you hold objects which are shared with other instances, don't clone them.
      • If you hold objects which must be unique, clone them.
      • If you hold objects which were given to you as a gesture of kindness, and aren't owned by you, you probably shouldn't clone them.
      • DON'T attempt to clone: Singletons, Cliques, or Populations, or Subpopulation.
      • Arrays are not cloned automatically; you may need to clone an array if you're not sharing it with other instances. Arrays have the nice feature of being copyable by calling clone() on them.

      Implementations.

      • If no ancestor of yours implements clone(), and you have no need to do clone deeply, and you are abstract, then you should not declare clone().
      • If no ancestor of yours implements clone(), and you have no need to do clone deeply, and you are not abstract, then you should implement it as follows: 

         public Object clone() 
     {
     try
         { 
         return super.clone();
         }
     catch ((CloneNotSupportedException e)
         { throw new InternalError(); } // never happens
     }
      • If no ancestor of yours implements clone(), but you need to deep-clone some things, then you should implement it as follows: 

         public Object clone() 
     {
     try
         { 
         MyObject myobj = (MyObject) (super.clone());

         // put your deep-cloning code here...
         }
     catch ((CloneNotSupportedException e)
         { throw new InternalError(); } // never happens
     return myobj;
     }
      • If an ancestor has implemented clone(), and you also need to deep clone some things, then you should implement it as follows: 

         public Object clone() 
     { 
     MyObject myobj = (MyObject) (super.clone());

     // put your deep-cloning code here...

     return myobj;
     }
      Specified by:
      clone in interface Prototype
      Overrides:
      clone in class Problem

    • prepareToEvaluate

      public void prepareToEvaluate(EvolutionState state, int threadnum)
      Description copied from class: Problem
      May be called by the Evaluator prior to a series of individuals to evaluate, and then ended with a finishEvaluating(...). If this is the case then the Problem is free to delay modifying the individuals or their fitnesses until at finishEvaluating(...). If no prepareToEvaluate(...) is called prior to evaluation, the Problem must complete its modification of the individuals and their fitnesses as they are evaluated as stipulated in the relevant evaluate(...) documentation for SimpleProblemForm or GroupedProblemForm. The default method does nothing. Note that prepareToEvaluate() can be called *multiple times* prior to finishEvaluating() being called -- in this case, the subsequent calls may be ignored.
      Overrides:
      prepareToEvaluate in class Problem

    • finishEvaluating

      public void finishEvaluating(EvolutionState state, int threadnum)
      Description copied from class: Problem
      Will be called by the Evaluator after prepareToEvaluate(...) is called and then a series of individuals are evaluated. However individuals may be evaluated without prepareToEvaluate or finishEvaluating being called at all. See the documentation for prepareToEvaluate for more information. The default method does nothing.
      Overrides:
      finishEvaluating in class Problem

    • initializeContacts

      public void initializeContacts(EvolutionState state)
      Description copied from class: Problem
      Called to set up remote evaluation network contacts when the run is started. By default does nothing.
      Overrides:
      initializeContacts in class Problem

    • reinitializeContacts

      public void reinitializeContacts(EvolutionState state)
      Description copied from class: Problem
      Called to reinitialize remote evaluation network contacts when the run is restarted from checkpoint. By default does nothing.
      Overrides:
      reinitializeContacts in class Problem

    • closeContacts

      public void closeContacts(EvolutionState state, int result)
      Description copied from class: Problem
      Called to shut down remote evaluation network contacts when the run is completed. By default does nothing.
      Overrides:
      closeContacts in class Problem

    • canEvaluate

      public boolean canEvaluate()
      Description copied from class: Problem
      Asynchronous Steady-State EC only: Returns true if the problem is ready to evaluate. In most cases, the default is true.
      Overrides:
      canEvaluate in class Problem

    • preprocessPopulation

      public void preprocessPopulation(EvolutionState state, Population pop, boolean[] prepareForFitnessAssessment, boolean countVictoriesOnly)
      Description copied from interface: GroupedProblemForm
      Set up the population pop (such as fitness information) prior to evaluation. Although this method is not static, you should not use it to write to any instance variables in the GroupedProblem instance; this is because it's possible that the instance used is in fact the prototype, and you will have no guarantees that your instance variables will remain valid during the evaluate(...) process. Do not assume that pop will be the same as state.pop -- it may not. state is only provided to give you access to EvolutionState features. Typically you'd use this method to set the Fitness values of all Individuals to 0.

      countVictoriesOnly will be set if Individuals' fitness is to be based on whether they're the winner of a test, instead of based on the specifics of the scores in the tests. This really only happens for Single-Elimination Tournament one-population competitive coevolution.

      prepareForFitnessAssessment will indicate which subpopulations will have their fitness values updated this time around, during postprocessPopulation. It may not be the same as updateFitness[] in evaluate(...).

      If you are basing fitness on trials, this method should create the initial trials if the prepareForFitnessAssessment[...] is true for that subpopulation.

      Specified by:
      preprocessPopulation in interface GroupedProblemForm

    • postprocessPopulation

      public int postprocessPopulation(EvolutionState state, Population pop, boolean[] assessFitness, boolean countVictoriesOnly)
      Description copied from interface: GroupedProblemForm
      Finish processing the population (such as fitness information) after evaluation. Although this method is not static, you should not use it to write to any instance variables in the GroupedProblem instance; this is because it's possible that the instance used is in fact the prototype, and you will have no guarantees that your instance variables will remain valid during the evaluate(...) process. Do not assume that pop will be the same as state.pop -- it may not. state is only provided to give you access to EvolutionState features.

      countVictoriesOnly will be set if Individuals' fitness is to be based on whether they're the winner of a test, instead of based on the specifics of the scores in the tests. This really only happens for Single-Elimination Tournament one-population competitive coevolution. If this is set, probably would leave the Fitnesses as they are here (they've been set and incremented in evaluate(...)), but if it's not set, you may want to set the Fitnesses to the maximum or average or the various trials performed.

      assessFitness will indicate which subpopulations should have their final fitness values assessed. You should not clear the trials of individuals for which assessFitness[] is false. Instead allow trials to accumulate and ultimately update the fitnesses later when the flag is set. assessFitness[] may not be the same as updateFitness[] in evaluate(...).

      Should return the number of individuals evaluated (not tested: but actually had their fitnesses modified -- or would have if the evaluated flag wasn't set).

      Specified by:
      postprocessPopulation in interface GroupedProblemForm

    • evaluate

      public void evaluate(EvolutionState state, Individual[] ind, boolean[] updateFitness, boolean countVictoriesOnly, int[] subpops, int threadnum)
      Default version assumes that every individual is a GEIndividual. The underlying problem.evaluate() must be prepared for the possibility that some GPIndividuals handed it are in fact null, meaning that they couldn't be extracted from the GEIndividual string. You should assign them bad fitness in some appropriate way.
      Specified by:
      evaluate in interface GroupedProblemForm

    • evaluate

      public void evaluate(EvolutionState state, Individual ind, int subpopulation, int threadnum)
      Description copied from interface: SimpleProblemForm
      Evaluates the individual in ind, if necessary (perhaps not evaluating them if their evaluated flags are true), and sets their fitness appropriately.
      Specified by:
      evaluate in interface SimpleProblemForm

    • describe

      public void describe(EvolutionState state, Individual ind, int subpopulation, int threadnum, int log)
      Description copied from class: Problem
      Part of SimpleProblemForm. Included here so you don't have to write the default version, which usually does nothing.
      Specified by:
      describe in interface SimpleProblemForm
      Overrides:
      describe in class Problem

    • isGroupedProblem

      public boolean isGroupedProblem()
      Description copied from class: Problem
      Returns true if this method is meant to be a grouped problem. You should not override this method: by default it simply returns (this instanceof GroupedProblemForm), but some wrapper problems override it to query their underlying Problems. The purpose of this method is to enable objects to dynamically indicate that they support GroupedProblemForm (perhaps they are a wrapper object around an underlying object which might or might not support it).
      Overrides:
      isGroupedProblem in class Problem