ec.gp.breed
Class RehangPipeline
java.lang.Object
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+--ec.BreedingSource
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+--ec.BreedingPipeline
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+--ec.gp.GPBreedingPipeline
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+--ec.gp.breed.RehangPipeline
- public class RehangPipeline
- extends GPBreedingPipeline
RehangPipeline picks a nonterminal node other than the root
and "rehangs" it as
a new root. Imagine if the tree were nodes connected with string.
Grab the new node and pick it up, letting the other nodes hang
underneath it as a new "root". That's in effect what you're doing.
Important Note: Because it must be free of any constraints
by nature, RehangPipeline does not work with strong typing. You must
not have more than one type defined in order to use RehangPipeline.
RehangPipeline picks a random tree, then picks randomly from
all the nonterminals in the tree other than the root, and rehangs the
chosen nonterminal
as the new root. If its chosen tree has no nonterminals, it repeats
the choose-tree process. If after tries times
it has failed to find a tree with nonterminals (other than the root),
it gives up and simply
copies the individual. As you might guess, determining if a tree has
nonterminals is very fast, so tries can be pretty large with
little to no detriment to evolution speed.
"Rehanging" is complicated to describe. First, you pick a random
child of your chosen nonterminal n,
and remove this subtree from the tree.
Call this subtree T. Next, you set the nonterminal as a new root; its
former parent p now fills the slot left behind by the missing subtree.
The p's former parent q now fills the slot left behind by
n. q's former parent r now fills the slot left behind
by p, and so on. This proceeds all the way up to the old root, which
will be left with one empty slot (where its former child was that is now its new
parent). This slot is then filled with T
Typical Number of Individuals Produced Per produce(...) call
1
Number of Sources
1
Parameters
base.tries
int >= 1 |
(number of times to try finding valid pairs of nodes) |
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.rehang
- See Also:
- Serialized Form
Method Summary |
Parameter |
defaultBase()
Returns the default base for this prototype. |
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. |
int |
typicalIndsProduced()
Returns 1 |
Methods inherited from class java.lang.Object |
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait |
P_REHANG
public static final java.lang.String P_REHANG
P_NUM_TRIES
public static final java.lang.String P_NUM_TRIES
INDS_PRODUCED
public static final int INDS_PRODUCED
NUM_SOURCES
public static final int NUM_SOURCES
RehangPipeline
public RehangPipeline()
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.
- Overrides:
- numSources in class BreedingPipeline
typicalIndsProduced
public int typicalIndsProduced()
- Returns 1
- Overrides:
- typicalIndsProduced in class BreedingSource
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}.
- Overrides:
- setup in class BreedingPipeline
- Tags copied from class: BreedingSource
- See Also:
Prototype.setup(EvolutionState,Parameter)
produce
public int produce(int min,
int max,
int start,
int subpopulation,
Individual[] inds,
EvolutionState state,
int thread)
throws java.lang.CloneNotSupportedException
- 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.
- Overrides:
- produce in class BreedingSource