ec.gp.breed
Class MutateERCPipeline

java.lang.Object
  extended by ec.BreedingSource
      extended by ec.BreedingPipeline
          extended by ec.gp.GPBreedingPipeline
              extended by ec.gp.breed.MutateERCPipeline
All Implemented Interfaces:
Prototype, Setup, SteadyStateBSourceForm, RandomChoiceChooser, java.io.Serializable, java.lang.Cloneable

public class MutateERCPipeline
extends GPBreedingPipeline

MutateERCPipeline works very similarly to the "Gaussian" algorithm described in Kumar Chellapilla, "A Preliminary Investigation into Evolving Modular Programs without Subtree Crossover", GP98.

MutateERCPipeline picks a random node from a random tree in the individual, using its node selector. It then proceeds to "mutate" every ERC (ephemeral random constant) located in the subtree rooted at that node. It does this by calling each ERC's mutateERC() method. The default form of mutateERC() method is to simply call resetNode(), thus randomizing the ERC; you may want to override this default to provide more useful mutations, such as adding gaussian noise.

Typical Number of Individuals Produced Per produce(...) call
...as many as the source produces

Number of Sources
1

Parameters

base.ns.0
classname, inherits and != GPNodeSelector
(GPNodeSelector for tree)
base.tree.0
0 < int < (num trees in individuals), if exists
(tree chosen for mutation; if parameter doesn't exist, tree is picked at random)

Default Base
gp.breed.mutate-erc

Parameter bases

base.ns
The GPNodeSelector selector

Version:
1.0
Author:
Sean Luke
See Also:
Serialized Form

Field Summary
 GPNodeSelector nodeselect
          How the pipeline chooses a subtree to mutate
static int NUM_SOURCES
           
static java.lang.String P_MUTATEERC
           
 
Fields inherited from class ec.gp.GPBreedingPipeline
P_NODESELECTOR, P_TREE, TREE_UNFIXED
 
Fields inherited from class ec.BreedingPipeline
DYNAMIC_SOURCES, mybase, P_NUMSOURCES, P_SOURCE, sources, V_SAME
 
Fields inherited from class ec.BreedingSource
CHECKBOUNDARY, DEFAULT_PRODUCED, NO_PROBABILITY, P_PROB, probability, UNUSED
 
Constructor Summary
MutateERCPipeline()
           
 
Method Summary
 java.lang.Object clone()
          Creates a new individual cloned from a prototype, and suitable to begin use in its own evolutionary context.
 Parameter defaultBase()
          Returns the default base for this prototype.
 void mutateERCs(GPNode node, EvolutionState state, int thread)
           
 int numSources()
          Returns the number of sources to this pipeline.
 int produce(int min, int max, int start, int subpopulation, Individual[] inds, EvolutionState state, int thread)
          Produces n individuals from the given subpopulation and puts them into inds[start...start+n-1], where n = Min(Max(q,min),max), where q is the "typical" number of individuals the BreedingSource produces in one shot, and returns n.
 void setup(EvolutionState state, Parameter base)
          Sets up the BreedingPipeline.
 
Methods inherited from class ec.gp.GPBreedingPipeline
produces
 
Methods inherited from class ec.BreedingPipeline
finishProducing, individualReplaced, maxChildProduction, minChildProduction, preparePipeline, prepareToProduce, sourcesAreProperForm, typicalIndsProduced
 
Methods inherited from class ec.BreedingSource
getProbability, pickRandom, setProbability, setupProbabilities
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

P_MUTATEERC

public static final java.lang.String P_MUTATEERC
See Also:
Constant Field Values

NUM_SOURCES

public static final int NUM_SOURCES
See Also:
Constant Field Values

nodeselect

public GPNodeSelector nodeselect
How the pipeline chooses a subtree to mutate

Constructor Detail

MutateERCPipeline

public MutateERCPipeline()
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(...).


numSources

public int numSources()
Description copied from class: BreedingPipeline
Returns the number of sources to this pipeline. Called during BreedingPipeline's setup. Be sure to return a value > 0, or DYNAMIC_SOURCES which indicates that setup should check the parameter file for the parameter "num-sources" to make its determination.

Specified by:
numSources in class BreedingPipeline

clone

public java.lang.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:

Implementations.

Specified by:
clone in interface Prototype
Overrides:
clone in class BreedingPipeline

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 BreedingPipeline
See Also:
Prototype.setup(EvolutionState,Parameter)

mutateERCs

public final void mutateERCs(GPNode node,
                             EvolutionState state,
                             int thread)

produce

public int produce(int min,
                   int max,
                   int start,
                   int subpopulation,
                   Individual[] inds,
                   EvolutionState state,
                   int thread)
Description copied from class: BreedingSource
Produces n individuals from the given subpopulation and puts them into inds[start...start+n-1], where n = Min(Max(q,min),max), where q is the "typical" number of individuals the BreedingSource produces in one shot, and returns n. max must be >= min, and min must be >= 1. For example, crossover might typically produce two individuals, tournament selection might typically produce a single individual, etc.

Specified by:
produce in class BreedingSource