#include <itkParticleSwarmOptimizer.h>

Inheritance diagram for itk::ParticleSwarmOptimizer:

Collaboration diagram for itk::ParticleSwarmOptimizer:

Detailed Description

Implementation of a Particle Swarm Optimization (PSO) algorithm.

The PSO algorithm was originally presented in:
J. Kennedy, R. Eberhart, "Particle Swarm Optimization", Proc. IEEE Int. Neural Networks, 1995.

The algorithm uses a stochastic optimization approach. Optimization is performed by maintaining a swarm (flock) of particles that traverse the parameter space, searching for the optimal function value. Associated with each particle are its location and speed, in parameter space. A particle's next location is determined by its current location, its current speed, the location of the best function value it previously encountered, and the location of the best function value the particles in its neighborhood previously encountered. In this implementation we use a global neighborhood with the following update equations:

$v_i(t+1) = wv_i(t) + c_1u_1(p_i-x_i(t)) + c_2u_2(p_g-x_i(t))$

$x_i(t+1) = clampToBounds(x_i(t) + v_i(t+1))$

where $u_i$ are $~U(0,1)$ and $w,c_1,c_2$ are user selected weights.

Swarm initialization is performed within the user supplied parameter bounds using a uniform distribution or a normal distribution centered on the initial parameter values supplied by the user. The search terminates when the maximal number of iterations has been reached or when the change in the best value in the past $g$ generations is below a threshold and the swarm has collapsed (i.e. particles are close to each other in parameter space).

NOTE: This implementation only performs minimization.

Definition at line 60 of file itkParticleSwarmOptimizer.h.

Public Types
using	ConstPointer = SmartPointer< const Self >

using	Pointer = SmartPointer< Self >

using	Self = ParticleSwarmOptimizer

using	Superclass = ParticleSwarmOptimizerBase

Public Types inherited from itk::ParticleSwarmOptimizerBase
using	ConstPointer = SmartPointer< const Self >

using	MeasureType = CostFunctionType::MeasureType

using	NumberOfGenerationsType = unsigned int

using	NumberOfIterationsType = unsigned int

using	NumberOfParticlesType = unsigned int

using	ParameterBoundsType = std::vector< std::pair< ParametersType::ValueType, ParametersType::ValueType > >

using	Pointer = SmartPointer< Self >

using	RandomVariateGeneratorType = Statistics::MersenneTwisterRandomVariateGenerator

using	Self = ParticleSwarmOptimizerBase

using	Superclass = SingleValuedNonLinearOptimizer

using	SwarmType = std::vector< ParticleData >

using	ValueType = ParametersType::ValueType

Public Types inherited from itk::SingleValuedNonLinearOptimizer
using	ConstPointer = SmartPointer< const Self >

using	CostFunctionPointer = CostFunctionType::Pointer

using	CostFunctionType = SingleValuedCostFunction

using	DerivativeType = CostFunctionType::DerivativeType

using	MeasureType = CostFunctionType::MeasureType

using	ParametersType = Superclass::ParametersType

using	Pointer = SmartPointer< Self >

using	Self = SingleValuedNonLinearOptimizer

using	Superclass = NonLinearOptimizer

Public Types inherited from itk::NonLinearOptimizer
using	ConstPointer = SmartPointer< const Self >

using	ParametersType = Superclass::ParametersType

using	Pointer = SmartPointer< Self >

using	ScalesType = Superclass::ScalesType

using	Self = NonLinearOptimizer

using	Superclass = Optimizer

Public Types inherited from itk::Optimizer
using	ConstPointer = SmartPointer< const Self >

using	ParametersType = OptimizerParameters< double >

using	Pointer = SmartPointer< Self >

using	ScalesType = Array< double >

using	Self = Optimizer

using	Superclass = Object

Public Types inherited from itk::Object
using	ConstPointer = SmartPointer< const Self >

using	Pointer = SmartPointer< Self >

using	Self = Object

using	Superclass = LightObject

Public Types inherited from itk::LightObject
using	ConstPointer = SmartPointer< const Self >

using	Pointer = SmartPointer< Self >

using	Self = LightObject

Public Member Functions
virtual ::itk::LightObject::Pointer	CreateAnother () const

virtual double	GetGlobalCoefficient ()

virtual double	GetInertiaCoefficient ()

virtual const char *	GetNameOfClass () const

virtual double	GetPersonalCoefficient ()

virtual void	SetGlobalCoefficient (double _arg)

virtual void	SetInertiaCoefficient (double _arg)

virtual void	SetPersonalCoefficient (double _arg)

Public Member Functions inherited from itk::ParticleSwarmOptimizerBase
virtual MeasureType	GetFunctionConvergenceTolerance ()

virtual bool	GetInitializeNormalDistribution ()

virtual NumberOfIterationsType	GetMaximalNumberOfIterations ()

virtual NumberOfGenerationsType	GetNumberOfGenerationsWithMinimalImprovement ()

virtual NumberOfParticlesType	GetNumberOfParticles ()

ParameterBoundsType	GetParameterBounds () const

virtual ParametersType	GetParametersConvergenceTolerance ()

virtual double	GetPercentageParticlesConverged ()

virtual bool	GetPrintSwarm ()

virtual RandomVariateGeneratorType::IntegerType	GetSeed ()

const std::string	GetStopConditionDescription () const override

virtual bool	GetUseSeed ()

MeasureType	GetValue () const

virtual void	InitializeNormalDistributionOff ()

virtual void	InitializeNormalDistributionOn ()

void	PrintSwarm (std::ostream &os, Indent indent) const

virtual void	PrintSwarmOff ()

virtual void	PrintSwarmOn ()

virtual void	SetFunctionConvergenceTolerance (MeasureType _arg)

virtual void	SetInitializeNormalDistribution (bool _arg)

virtual void	SetMaximalNumberOfIterations (NumberOfIterationsType _arg)

virtual void	SetNumberOfGenerationsWithMinimalImprovement (NumberOfGenerationsType _arg)

void	SetNumberOfParticles (NumberOfParticlesType n)

void	SetParametersConvergenceTolerance (ValueType convergenceTolerance, unsigned int sz)

virtual void	SetParametersConvergenceTolerance (ParametersType _arg)

virtual void	SetPercentageParticlesConverged (double _arg)

virtual void	SetPrintSwarm (bool _arg)

virtual void	SetSeed (RandomVariateGeneratorType::IntegerType _arg)

virtual void	SetUseSeed (bool _arg)

void	StartOptimization () override

virtual void	UseSeedOff ()

virtual void	UseSeedOn ()

void	SetInitialSwarm (const SwarmType &initialSwarm)

void	ClearSwarm ()

virtual void	SetParameterBounds (ParameterBoundsType &bounds)

void	SetParameterBounds (std::pair< ParametersType::ValueType, ParametersType::ValueType > &bounds, unsigned int n)

Public Member Functions inherited from itk::SingleValuedNonLinearOptimizer
virtual ::itk::LightObject::Pointer	CreateAnother () const

virtual const CostFunctionType *	GetCostFunction () const

virtual CostFunctionType *	GetModifiableCostFunction ()

MeasureType	GetValue (const ParametersType &parameters) const

virtual void	SetCostFunction (CostFunctionType *costFunction)

Public Member Functions inherited from itk::Optimizer
virtual const ParametersType &	GetCurrentPosition () const

virtual const ParametersType &	GetInitialPosition () const

virtual void	SetInitialPosition (const ParametersType &param)

void	SetScales (const ScalesType &scales)

virtual const ScalesType &	GetScales () const

virtual const ScalesType &	GetInverseScales () const

Public Member Functions inherited from itk::Object
unsigned long	AddObserver (const EventObject &event, Command *)

unsigned long	AddObserver (const EventObject &event, Command *) const

virtual void	DebugOff () const

virtual void	DebugOn () const

Command *	GetCommand (unsigned long tag)

bool	GetDebug () const

MetaDataDictionary &	GetMetaDataDictionary ()

const MetaDataDictionary &	GetMetaDataDictionary () const

virtual ModifiedTimeType	GetMTime () const

virtual const TimeStamp &	GetTimeStamp () const

bool	HasObserver (const EventObject &event) const

void	InvokeEvent (const EventObject &)

void	InvokeEvent (const EventObject &) const

virtual void	Modified () const

void	Register () const override

void	RemoveAllObservers ()

void	RemoveObserver (unsigned long tag)

void	SetDebug (bool debugFlag) const

void	SetReferenceCount (int) override

void	UnRegister () const noexceptoverride

void	SetMetaDataDictionary (const MetaDataDictionary &rhs)

void	SetMetaDataDictionary (MetaDataDictionary &&rrhs)

virtual void	SetObjectName (std::string _arg)

virtual const std::string &	GetObjectName () const

Public Member Functions inherited from itk::LightObject
virtual void	Delete ()

virtual int	GetReferenceCount () const

	itkCloneMacro (Self)

void	Print (std::ostream &os, Indent indent=0) const

Static Public Member Functions
static Pointer	New ()

Static Public Member Functions inherited from itk::SingleValuedNonLinearOptimizer
static Pointer	New ()

Static Public Member Functions inherited from itk::NonLinearOptimizer
static Pointer	New ()

Static Public Member Functions inherited from itk::Optimizer
static Pointer	New ()

Static Public Member Functions inherited from itk::Object
static bool	GetGlobalWarningDisplay ()

static void	GlobalWarningDisplayOff ()

static void	GlobalWarningDisplayOn ()

static Pointer	New ()

static void	SetGlobalWarningDisplay (bool flag)

Static Public Member Functions inherited from itk::LightObject
static void	BreakOnError ()

static Pointer	New ()

Protected Member Functions
	ParticleSwarmOptimizer ()

void	PrintSelf (std::ostream &os, Indent indent) const override

void	UpdateSwarm () override

	~ParticleSwarmOptimizer () override

Protected Member Functions inherited from itk::ParticleSwarmOptimizerBase
void	FileInitialization ()

virtual void	Initialize ()

	ParticleSwarmOptimizerBase ()

void	PrintParamtersType (const ParametersType &x, std::ostream &os) const

void	PrintSelf (std::ostream &os, Indent indent) const override

void	RandomInitialization ()

virtual void	ValidateSettings ()

	~ParticleSwarmOptimizerBase () override

Protected Member Functions inherited from itk::SingleValuedNonLinearOptimizer
void	PrintSelf (std::ostream &os, Indent indent) const override

	SingleValuedNonLinearOptimizer ()

	~SingleValuedNonLinearOptimizer () override=default

Protected Member Functions inherited from itk::NonLinearOptimizer
	NonLinearOptimizer ()=default

	~NonLinearOptimizer () override

Protected Member Functions inherited from itk::Optimizer
	Optimizer ()

virtual void	SetCurrentPosition (const ParametersType &param)

	~Optimizer () override=default

Protected Member Functions inherited from itk::Object
	Object ()

bool	PrintObservers (std::ostream &os, Indent indent) const

virtual void	SetTimeStamp (const TimeStamp &time)

	~Object () override

Protected Member Functions inherited from itk::LightObject
virtual LightObject::Pointer	InternalClone () const

	LightObject ()

virtual void	PrintHeader (std::ostream &os, Indent indent) const

virtual void	PrintTrailer (std::ostream &os, Indent indent) const

virtual	~LightObject ()

Private Attributes
ParametersType::ValueType	m_GlobalCoefficient

ParametersType::ValueType	m_InertiaCoefficient

ParametersType::ValueType	m_PersonalCoefficient

Additional Inherited Members
Protected Attributes inherited from itk::ParticleSwarmOptimizerBase
CostFunctionType::MeasureType	m_FunctionBestValue {0}

std::vector< MeasureType >	m_FunctionBestValueMemory

CostFunctionType::MeasureType	m_FunctionConvergenceTolerance

bool	m_InitializeNormalDistribution

NumberOfIterationsType	m_IterationIndex {0}

NumberOfIterationsType	m_MaximalNumberOfIterations

NumberOfGenerationsType	m_NumberOfGenerationsWithMinimalImprovement

NumberOfParticlesType	m_NumberOfParticles

ParameterBoundsType	m_ParameterBounds

ParametersType	m_ParametersBestValue

ParametersType	m_ParametersConvergenceTolerance

std::vector< ParticleData >	m_Particles

double	m_PercentageParticlesConverged

bool	m_PrintSwarm

RandomVariateGeneratorType::IntegerType	m_Seed

std::ostringstream	m_StopConditionDescription

bool	m_UseSeed

Protected Attributes inherited from itk::SingleValuedNonLinearOptimizer
CostFunctionPointer	m_CostFunction

Protected Attributes inherited from itk::Optimizer
ParametersType	m_CurrentPosition

bool	m_ScalesInitialized { false }

Protected Attributes inherited from itk::LightObject
std::atomic< int >	m_ReferenceCount

Member Typedef Documentation

using itk::ParticleSwarmOptimizer::ConstPointer = SmartPointer<const Self>

Definition at line 70 of file itkParticleSwarmOptimizer.h.

using itk::ParticleSwarmOptimizer::Pointer = SmartPointer<Self>

Definition at line 69 of file itkParticleSwarmOptimizer.h.

using itk::ParticleSwarmOptimizer::Self = ParticleSwarmOptimizer

Standard "Self" type alias.

Definition at line 67 of file itkParticleSwarmOptimizer.h.

using itk::ParticleSwarmOptimizer::Superclass = ParticleSwarmOptimizerBase

Definition at line 68 of file itkParticleSwarmOptimizer.h.

Constructor & Destructor Documentation

itk::ParticleSwarmOptimizer::ParticleSwarmOptimizer ( )

protected

itk::ParticleSwarmOptimizer::~ParticleSwarmOptimizer ( )

overrideprotected

Member Function Documentation

virtual::itk::LightObject::Pointer itk::ParticleSwarmOptimizer::CreateAnother ( ) const

virtual

Create an object from an instance, potentially deferring to a factory. This method allows you to create an instance of an object that is exactly the same type as the referring object. This is useful in cases where an object has been cast back to a base class.

Reimplemented from itk::NonLinearOptimizer.

virtual double itk::ParticleSwarmOptimizer::GetGlobalCoefficient ( )

virtual

virtual double itk::ParticleSwarmOptimizer::GetInertiaCoefficient ( )

virtual

virtual const char* itk::ParticleSwarmOptimizer::GetNameOfClass ( ) const

virtual

Run-time type information (and related methods).

Reimplemented from itk::ParticleSwarmOptimizerBase.

virtual double itk::ParticleSwarmOptimizer::GetPersonalCoefficient ( )

virtual

static Pointer itk::ParticleSwarmOptimizer::New ( )

static

Method for creation through the object factory.

Examples:: Examples/IO/XML/ParticleSwarmOptimizerReadWrite.cxx.

void itk::ParticleSwarmOptimizer::PrintSelf	(	std::ostream &	os,
		Indent	indent
	)		const

overrideprotectedvirtual

Methods invoked by Print() to print information about the object including superclasses. Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from itk::Optimizer.

virtual void itk::ParticleSwarmOptimizer::SetGlobalCoefficient ( double _arg )

virtual

virtual void itk::ParticleSwarmOptimizer::SetInertiaCoefficient ( double _arg )

virtual

The Particle swarm optimizer uses the following update formula: v_i(t+1) = w*v_i(t) + c_1*uniform(0,1)*(p_i-x_i(t)) + c_2*uniform(0,1)*(p_g-x_i(t)) x_i(t+1) = clampToBounds(x_i(t) + v_i(t+1)) where w - inertia constant c_1 - personal coefficient c_2 - global coefficient p_i - parameters yielding the best function value obtained by this particle p_g - parameters yielding the best function value obtained by all particles

virtual void itk::ParticleSwarmOptimizer::SetPersonalCoefficient ( double _arg )

virtual

void itk::ParticleSwarmOptimizer::UpdateSwarm ( )

overrideprotectedvirtual

Implement your update rule in this function.

Implements itk::ParticleSwarmOptimizerBase.