net.openai.ai.ga.population
Class Population

java.lang.Object
  |
  +--net.openai.ai.ga.population.Population

All Implemented Interfaces:

java.io.Serializable

public class Population

extends java.lang.Object

implements java.io.Serializable

The Population is the encapsulation of the individual solutions ( Cells that are used to solve the problem. Cells may be added and deleted from this collection. This also implements the following functions, which are passed on to the appropriate targets:

• Mature (or age)
• Evaluate
• Combine (or reproduce)
• Mutate

Since:

JDK1.3

Version:

%I%, %G%

Author:

Jared Grubb

See Also:

Serialized Form

Field Summary

protected java.util.Collection	cells The collection of cells that are in this Population
boolean	toStringQuiet Determines whether to display anything on a toString() call.
boolean	toStringUsesCells Determines whether to call all the Cells to return something as well.
boolean	toStringUsesSize Determines whether to display the size of the Population
boolean	toStringUsesTopCell Determines whether the Cell with the highest fitness is displayed.

Constructor Summary

Population()
Creates a population using an ArrayList

Population(java.util.Collection initialCollection)
Creates a population using a given Collection

Population(Population toClone)
Creates a partial clone of this Population.

Population(Population toClone, boolean makeEmpty)
Creates a partial clone of this Population.

Method Summary

void	addCell(Cell toAdd) Adds a Cell to this Population.
void	addCells(Population toAdd) Adds all the Cells in the given Population.
void	cleanse() Removes non-Cell objects from the Collection
void	combine(PopulationArray parents) Creates new Cells to add into the Population.
static void	condemnPopulation(Population toCondemn) Condemns all the Cells in the given Population .
void	evaluate(Environment env) Tells each Cell in this Population to evaluate its fitness based upon the Environment given to it.
Cell	getCell(int index) Returns a Cell from this Population with the given index.
Cell[]	getCellArray() Returns a Cell[] array representing all the Cell s in this population.
java.util.Iterator	getCellIterator() Returns an Iterator to be used to iterate through all the Cell in this Population.
java.util.Collection	getCells() Returns the Collection used internally to represent the members of the population
int	getSize() Returns the number of Cells in this Population .
void	mature() Matures the population.
static void	mutate(Population toMutate) Issues a mutate command to each cell in the passed Population .
void	removeAllCellsBut(Population toKeep) Removes all the Cells from this Population except those specified in the passed Population.
void	removeAllSameAs(Cell toRemove) Removes all instances of Cell from this Population.
boolean	removeCell(Cell toRemove) Removes a Cell from this Population.
void	removeCells(Population toRemove) Removes a group of Cells from this Population .
java.lang.String	toString() Returns a String representation of this Population.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

cells

protected java.util.Collection cells

The collection of cells that are in this Population

toStringQuiet

public boolean toStringQuiet

Determines whether to display anything on a toString() call.

toStringUsesSize

public boolean toStringUsesSize

Determines whether to display the size of the Population

toStringUsesCells

public boolean toStringUsesCells

Determines whether to call all the Cells to return something as well.

toStringUsesTopCell

public boolean toStringUsesTopCell

Determines whether the Cell with the highest fitness is displayed.

Constructor Detail

Population

public Population()

Creates a population using an ArrayList

Population

public Population(java.util.Collection initialCollection)

Creates a population using a given Collection

Parameters:

initialCollection - a Collection to initialize with

Population

public Population(Population toClone)

Creates a partial clone of this Population. This is not a complete clone, in which each of the Cells would also be cloned; this instead creates a copy of the collection of Cells to which additions and removals do not affect the original population. Equilivant to Population(toClone,false) .

Population

public Population(Population toClone,
                  boolean makeEmpty)

Creates a partial clone of this Population. This is not a complete clone, in which each of the Cells would also be cloned; this instead creates a copy of the collection of Cells to which additions and removals do not affect the original population.

Method Detail

mature

public void mature()

Matures the population. Calls the mature() method of each of the Cells contained in this Population.

evaluate

public void evaluate(Environment env)

Tells each Cell in this Population to evaluate its fitness based upon the Environment given to it.

Parameters:

env - Environment to evaluate against

combine

public void combine(PopulationArray parents)

Creates new Cells to add into the Population. The groups of cells to combine are passed as a PopulationArray . The first Cell in each Population in the group is issued the combine method to return a new Cell which is then added into this Population.

Parameters:

parents - a PopulationArray containing sets of parents

mutate

public static void mutate(Population toMutate)

Issues a mutate command to each cell in the passed Population .

Parameters:

toMutate - the target Population for the mutation

getCellIterator

public java.util.Iterator getCellIterator()

Returns an Iterator to be used to iterate through all the Cell in this Population.

Returns:

an Iterator on the Cell collection

addCell

public void addCell(Cell toAdd)

Adds a Cell to this Population. Does nothing when given null.

Parameters:

toAdd - the Cell to add

addCells

public void addCells(Population toAdd)

Adds all the Cells in the given Population. Does nothing on null or an empty Population.

removeCell

public boolean removeCell(Cell toRemove)

Removes a Cell from this Population. Returns whether the removal was successful or not. Does nothing when given a null.

Parameters:

toRemove - the Cell to remove

Returns:

true on success; false otherwise;

removeCells

public void removeCells(Population toRemove)

Removes a group of Cells from this Population . Does not indicate whether the removal was successful or not. Does nothing when given a null or an empty Population.

removeAllCellsBut

public void removeAllCellsBut(Population toKeep)

Removes all the Cells from this Population except those specified in the passed Population. Does not indicate whether the removal was successful or not. Does nothing when given a null or an empty Population.

removeAllSameAs

public void removeAllSameAs(Cell toRemove)

Removes all instances of Cell from this Population. Does not indicate whether any removal took place. Does nothing when given a null or a non-existant Cell.

Parameters:

toRemove - the Cell to remove

getCell

public Cell getCell(int index)

Returns a Cell from this Population with the given index.

This method is not recommended since access to the collection via an index is highly unreliable. This method is provided only to provide a way for mutation selection algorithm to access random elements of the Cell array without having to do constant array conversions.

Parameters:

index - the index of the Cell to return

Returns:

Cell at the given index

Throws:

java.lang.IndexOutOfBoundsException

getCellArray

public Cell[] getCellArray()

Returns a Cell[] array representing all the Cell s in this population. Returns an empty array when empty.

Returns:

Cell[] of all Cells

getCells

public java.util.Collection getCells()

Returns the Collection used internally to represent the members of the population

Returns:

Collection of all Cells

condemnPopulation

public static void condemnPopulation(Population toCondemn)

Condemns all the Cells in the given Population . Each Cell in the Population has its condemn() called. A null passed returns immediately.

Parameters:

toCondemn - the Population to condemn

getSize

public int getSize()

Returns the number of Cells in this Population .

Returns:

the number of Cells

cleanse

public void cleanse()

Removes non-Cell objects from the Collection

toString

public java.lang.String toString()

Returns a String representation of this Population. Uses the following boolean values to create the return String:

• toStringQuiet
• toStringUsesSize
• toStringUsesCells
• toStringUsesTopCell

Overrides:

toString in class java.lang.Object

Returns:

a String representation of the status