Class MutateDemotePipeline
- All Implemented Interfaces:
Prototype,Setup,SteadyStateBSourceForm,RandomChoiceChooserD,Serializable,Cloneable
MutateDemotePipeline tries picks a random tree, then picks randomly from all the demotable nodes in the tree, and demotes one. If its chosen tree has no demotable nodes, or demoting its chosen demotable node would make the tree too deep, it repeats the choose-tree-then-choose-node process. If after tries times it has failed to find a valid tree and demotable node, it gives up and simply copies the individual.
"Demotion" means to take a node n and insert a new node m between n and n's parent. n becomes a child of m; the place where it becomes a child is determined at random from all the type-compatible slots of m. The other child slots of m are filled with randomly-generated terminals. Chellapilla's version of the algorithm always places n in child slot 0 of m. Because this would be unneccessarily restrictive on strong typing, MutateDemotePipeline instead picks the slot at random from all available valid choices.
A "Demotable" node means a node which is capable of demotion given the existing function set. In general to demote a node foo, there must exist in the function set a nonterminal whose return type is type-compatible with the child slot foo holds in its parent; this nonterminal must also have a child slot which is type-compatible with foo's return type.
This method is very expensive in searching nodes for "demotability". However, if the number of types is 1 (the GP run is typeless) then the type-constraint-checking code is bypassed and the method runs a little faster.
Typical Number of Individuals Produced Per produce(...) call
...as many as the source produces
Number of Sources
1
Parameters
| base.tries int >= 1 |
(number of times to try finding valid pairs of nodes) |
| base.maxdepth int >= 1 |
(maximum valid depth of a mutated 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-demote
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Field Summary
FieldsModifier and TypeFieldDescriptionstatic final intstatic final Stringstatic final Stringstatic final StringFields inherited from class ec.gp.GPBreedingPipeline
P_NODESELECTOR, P_TREE, TREE_UNFIXEDFields inherited from class ec.BreedingPipeline
DYNAMIC_SOURCES, likelihood, mybase, P_LIKELIHOOD, P_NUMSOURCES, P_SOURCE, sources, V_SAME, V_STUBFields inherited from class ec.BreedingSource
NO_PROBABILITY, P_PROB, probability -
Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionReturns the default base for this prototype.intReturns the number of sources to this pipeline.intproduce(int min, int max, int subpopulation, ArrayList<Individual> inds, EvolutionState state, int thread, HashMap<String, Object> misc) 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.voidsetup(EvolutionState state, Parameter base) Sets up the BreedingPipeline.Methods inherited from class ec.gp.GPBreedingPipeline
producesMethods inherited from class ec.BreedingPipeline
clone, fillStubs, finishProducing, individualReplaced, maxChildProduction, minChildProduction, preparePipeline, prepareToProduce, sourcesAreProperForm, typicalIndsProducedMethods inherited from class ec.BreedingSource
getProbability, pickRandom, setProbability, setupProbabilities
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Field Details
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P_MUTATEDEMOTE
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P_NUM_TRIES
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P_MAXDEPTH
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NUM_SOURCES
public static final int NUM_SOURCES- See Also:
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Constructor Details
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MutateDemotePipeline
public MutateDemotePipeline()
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Method Details
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defaultBase
Description copied from interface:PrototypeReturns 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:BreedingPipelineReturns 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:
numSourcesin classBreedingPipeline
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setup
Description copied from class:BreedingSourceSets 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}.
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produce
public int produce(int min, int max, int subpopulation, ArrayList<Individual> inds, EvolutionState state, int thread, HashMap<String, Object> misc) Description copied from class:BreedingSourceProduces 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:
producein classBreedingSource
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