ec.exchange

Class InterPopulationExchange

java.lang.Object

ec.Exchanger

ec.exchange.InterPopulationExchange

All Implemented Interfaces:

Setup, Singleton, Serializable

public class InterPopulationExchange
extends Exchanger

InterPopulationExchange is an Exchanger which implements a simple exchanger between subpopulations. IterPopulationExchange uses an arbitrary graph topology for migrating individuals from subpopulations. The assumption is that all subpopulations have the same representation and same task to solve, otherwise the exchange between subpopulations does not make much sense.

InterPopulationExchange has a topology which is similar to the one used by IslandExchange. Every few generations, a subpopulation will send some number of individuals to other subpopulations. Since all subpopulations evolve at the same generational speed, this is a synchronous procedure (IslandExchange instead is asynchronous by default, though you can change it to synchronous).

Individuals are sent from a subpopulation prior to breeding. They are stored in a waiting area until after all subpopulations have bred; thereafter they are added into the new subpopulation. This means that the subpopulation order doesn't matter. Also note that it means that some individuals will be created during breeding, and immediately killed to make way for the migrants. A little wasteful, we know, but it's simpler that way.

Parameters

base.chatty boolean, default = true

Should we be verbose or silent about our exchanges?

Note: For each subpopulation in your population, there must be one exch.subpop... declaration set.

base.subpop.n.select classname, inherits and != ec.SelectionMethod	The selection method used by subpopulation #n for picking migrants to emigrate to other subpopulations. If not set, uses the default parameter below.
base.select classname, inherits and != ec.SelectionMethod	server: Default parameter: the selection method used by a given subpopulation for picking migrants to emigrate to other subpopulations.
base.subpop.n.select-to-die classname, inherits and != ec.SelectionMethod (Default is random selection)	The selection method used by subpopulation #n for picking individuals to be replaced by migrants. If not set, uses the default parameter below.
base.select-to-die classname, inherits and != ec.SelectionMethod (Default is random selection)	server: Default parameter: the selection method used by a given subpopulation for picking individuals to be replaced by migrants.
base.subpop.n.mod int >= 1	The number of generations that subpopulation #n waits between sending emigrants. If not set, uses the default parameter below.
base.mod int >= 1	server: Default parameter: the number of generations that a given subpopulation waits between sending emigrants.
base.subpop.n.start int >= 0	The generation when subpopulation #n begins sending emigrants. If not set, uses the default parameter below.
base.start int >= 0	server: Default parameter: the generation when a given subpopulation begins sending emigrants.
base.subpop.n.size int >= 0	The number of emigrants sent at one time by generation #n. If not set, uses the default parameter below.
base.subpop.n.num-dest int >= 0	The number of destination subpopulations for this subpopulation.
base.subpop.n.dest.m int >= 0	Subpopulation #n's destination #m is this subpopulation.

Parameter bases

base.subpop.n.select

selection method for subpopulation #n's migrants

Version:

2.0

Author:

Liviu Panait & Sean Luke

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) static class	InterPopulationExchange.IPEInformation

Field Summary

Fields

Modifier and Type	Field and Description
Parameter	base My parameter base -- I need to keep this in order to help the server reinitialize contacts
boolean	chatty
(package private) InterPopulationExchange.IPEInformation[]	exchangeInformation
(package private) Individual[][]	immigrants
(package private) int[]	nImmigrants
(package private) int	nrSources
static String	P_CHATTY Whether or not we're chatty
static String	P_DEST The prefix for destinations
static String	P_DEST_FOR_SUBPOP The number of destinations from current island
static String	P_MODULO The parameter for the modulo (how many generations should pass between consecutive sendings of individuals
static String	P_OFFSET How many generations to pass at the beginning of the evolution before the first emigration from the current subpopulation
static String	P_SELECT_METHOD The selection method for sending individuals to other islands
static String	P_SELECT_TO_DIE_METHOD The selection method for deciding individuals to be replaced by immigrants
static String	P_SIZE The number of emigrants to be sent
static String	P_SUBPOP The subpopulation delimiter
private static long	serialVersionUID

Constructor Summary

Constructors

Constructor and Description
InterPopulationExchange()

Method Summary

Methods

Modifier and Type	Method and Description
void	closeContacts(EvolutionState state, int result) Closes contacts with other processes, if that's what you're doing.
void	initializeContacts(EvolutionState state) Initializes contacts with other processes, if that's what you're doing.
Population	postBreedingExchangePopulation(EvolutionState state) Performs exchanges after the population has been bred but before it has been evaluated, once every generation (or pseudogeneration).
Population	preBreedingExchangePopulation(EvolutionState state) Performs exchanges after the population has been evaluated but before it has been bred, once every generation (or pseudogeneration).
void	reinitializeContacts(EvolutionState state) Initializes contacts with other processes, if that's what you're doing.
String	runComplete(EvolutionState state) Called after preBreedingExchangePopulation(...) to evaluate whether or not the exchanger wishes the run to shut down (with ec.EvolutionState.R_FAILURE).
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 ec.Exchanger

process

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

See Also:

Constant Field Values

P_SUBPOP

public static final String P_SUBPOP

The subpopulation delimiter

See Also:

Constant Field Values

P_MODULO

public static final String P_MODULO

The parameter for the modulo (how many generations should pass between consecutive sendings of individuals

See Also:

Constant Field Values

P_SIZE

public static final String P_SIZE

The number of emigrants to be sent

See Also:

Constant Field Values

P_OFFSET

public static final String P_OFFSET

How many generations to pass at the beginning of the evolution before the first emigration from the current subpopulation

See Also:

Constant Field Values

P_DEST_FOR_SUBPOP

public static final String P_DEST_FOR_SUBPOP

The number of destinations from current island

See Also:

Constant Field Values

P_DEST

public static final String P_DEST

The prefix for destinations

See Also:

Constant Field Values

P_SELECT_METHOD

public static final String P_SELECT_METHOD

The selection method for sending individuals to other islands

See Also:

Constant Field Values

P_SELECT_TO_DIE_METHOD

public static final String P_SELECT_TO_DIE_METHOD

The selection method for deciding individuals to be replaced by immigrants

See Also:

Constant Field Values

P_CHATTY

public static final String P_CHATTY

Whether or not we're chatty

See Also:

Constant Field Values

base

public Parameter base

My parameter base -- I need to keep this in order to help the server reinitialize contacts

exchangeInformation

InterPopulationExchange.IPEInformation[] exchangeInformation

immigrants

Individual[][] immigrants

nImmigrants

int[] nImmigrants

nrSources

int nrSources

chatty

public boolean chatty

Constructor Detail

InterPopulationExchange

public InterPopulationExchange()

Method Detail

setup

public void setup(EvolutionState state,
         Parameter _base)

Description copied from interface: Setup

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.

initializeContacts

public void initializeContacts(EvolutionState state)

Initializes contacts with other processes, if that's what you're doing. Called at the beginning of an evolutionary run, before a population is set up. It doesn't do anything, as this exchanger works on only 1 computer.

Overrides:

initializeContacts in class Exchanger

reinitializeContacts

public void reinitializeContacts(EvolutionState state)

Initializes contacts with other processes, if that's what you're doing. Called after restarting from a checkpoint. It doesn't do anything, as this exchanger works on only 1 computer.

Overrides:

reinitializeContacts in class Exchanger

preBreedingExchangePopulation

public Population preBreedingExchangePopulation(EvolutionState state)

Description copied from class: Exchanger

Performs exchanges after the population has been evaluated but before it has been bred, once every generation (or pseudogeneration).

Specified by:

preBreedingExchangePopulation in class Exchanger

postBreedingExchangePopulation

public Population postBreedingExchangePopulation(EvolutionState state)

Description copied from class: Exchanger

Performs exchanges after the population has been bred but before it has been evaluated, once every generation (or pseudogeneration).

Specified by:

postBreedingExchangePopulation in class Exchanger

runComplete

public String runComplete(EvolutionState state)

Called after preBreedingExchangePopulation(...) to evaluate whether or not the exchanger wishes the run to shut down (with ec.EvolutionState.R_FAILURE). This would happen for two reasons. First, another process might have found an ideal individual and the global run is now over. Second, some network or operating system error may have occurred and the system needs to be shut down gracefully. This function does not return a String as soon as it wants to exit (another island found the perfect individual, or couldn't connect to the server). Instead, it sets a flag, called message, to remember next time to exit. This is due to a need for a graceful shutdown, where checkpoints are working properly and save all needed information.

Specified by:

runComplete in class Exchanger

closeContacts

public void closeContacts(EvolutionState state,
                 int result)

Closes contacts with other processes, if that's what you're doing. Called at the end of an evolutionary run. result is either ec.EvolutionState.R_SUCCESS or ec.EvolutionState.R_FAILURE, indicating whether or not an ideal individual was found.

Overrides:

closeContacts in class Exchanger