ec.gp

Class GPNodeBuilder

java.lang.Object

ec.gp.GPNodeBuilder

All Implemented Interfaces:

Prototype, Setup, java.io.Serializable, java.lang.Cloneable

Direct Known Subclasses:

KozaBuilder, PTC1, PTC2, PushBuilder, RandomBranch, RandTree, Uniform

public abstract class GPNodeBuilder
extends java.lang.Object
implements Prototype

GPNodeBuilder is a Prototype which defines the superclass for objects which create ("grow") GP trees, whether for population initialization, subtree mutation, or whatnot. It defines a single abstract method, newRootedTree(...), which must be implemented to grow the tree.

GPNodeBuilder also provides some facilities for user-specification of probabilities of various tree sizes, which the tree builder can use as it sees fit (or totally ignore). There are two such facilities. First, the user might specify a minimum and maximum range for tree sizes to be picked from; trees would likely be picked uniformly from this range. Second, the user might specify an array, num-sizes long, of probabilities of tree sizes, in order to give a precise probability distribution.

Parameters

base.min-size int >= 1, or undefined	(smallest valid size, see discussion above)
base.max-size int >= min-size, or undefined	(largest valid size, see discussion above)
base.num-sizes int >= 1, or underfined	(number of sizes in the size distribution, see discussion above)
base.size.n 0.0 <= double <= 1.0, or undefined	(probability of choosing size n. See discussion above)

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	CHECK_BOUNDARY
int	maxSize the minium possible size -- if unused, it's 0
int	minSize
static int	NOSIZEGIVEN Produces a new rooted tree of GPNodes whose root's return type is swap-compatible with type.
static java.lang.String	P_MAXSIZE
static java.lang.String	P_MINSIZE
static java.lang.String	P_NUMSIZES
static java.lang.String	P_SIZE
double[]	sizeDistribution the maximum possible size -- if unused, it's 0

Constructor Summary

Constructors

Constructor and Description
GPNodeBuilder()

Method Summary

Modifier and Type	Method and Description
boolean	canPick() Returns true if some size distribution (either minSize and maxSize, or sizeDistribution) is set up by the user in order to pick sizes randomly.
java.lang.Object	clone() Creates a new individual cloned from a prototype, and suitable to begin use in its own evolutionary context.
abstract GPNode	newRootedTree(EvolutionState state, GPType type, int thread, GPNodeParent parent, GPFunctionSet set, int argposition, int requestedSize)
int	pickSize(EvolutionState state, int thread) Assuming that either minSize and maxSize, or sizeDistribution, is defined, picks a random size from minSize...maxSize inclusive, or randomly from sizeDistribution.
void	setup(EvolutionState state, Parameter base) Sets up the object by reading it from the parameters stored in state, built off of the parameter base base.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface ec.Prototype

defaultBase

Field Detail

NOSIZEGIVEN

public static final int NOSIZEGIVEN

Produces a new rooted tree of GPNodes whose root's return type is swap-compatible with type. When you build a brand-new tree out of GPNodes cloned from the prototypes stored in the GPNode[] arrays, you must remember to call resetNode() on each cloned GPNode. This gives ERCs a chance to randomize themselves and set themselves up.

requestedSize is an optional argument which differs based on the GPNodeBuilder used. Typically it is set to a tree size that the calling method wants the GPNodeBuilder to produce; the GPNodeBuilder is not obligated to produce a tree of this size, but it should attempt to interpret this argument as appropriate for the given algorithm. To indicate that you don't care what size the tree should be, you can pass NOSIZEGIVEN. However if the algorithm requires you to provide a size, it will generate a fatal error to let you know.

See Also:

Constant Field Values

CHECK_BOUNDARY

public static final int CHECK_BOUNDARY

See Also:

Constant Field Values

P_MINSIZE

public static final java.lang.String P_MINSIZE

See Also:

Constant Field Values

P_MAXSIZE

public static final java.lang.String P_MAXSIZE

See Also:

Constant Field Values

P_NUMSIZES

public static final java.lang.String P_NUMSIZES

See Also:

Constant Field Values

P_SIZE

public static final java.lang.String P_SIZE

See Also:

Constant Field Values

minSize

public int minSize

maxSize

public int maxSize

the minium possible size -- if unused, it's 0

sizeDistribution

public double[] sizeDistribution

the maximum possible size -- if unused, it's 0

Constructor Detail

GPNodeBuilder

public GPNodeBuilder()

Method Detail

canPick

public boolean canPick()

Returns true if some size distribution (either minSize and maxSize, or sizeDistribution) is set up by the user in order to pick sizes randomly.

pickSize

public int pickSize(EvolutionState state,
                    int thread)

Assuming that either minSize and maxSize, or sizeDistribution, is defined, picks a random size from minSize...maxSize inclusive, or randomly from sizeDistribution.

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:

• 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 Groups.
• 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 java.lang.Object

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

newRootedTree

public abstract GPNode newRootedTree(EvolutionState state,
                                     GPType type,
                                     int thread,
                                     GPNodeParent parent,
                                     GPFunctionSet set,
                                     int argposition,
                                     int requestedSize)