gum::Dirichlet Class Reference

A class for sampling w.r.t. More...

#include <agrum/base/core/math/Dirichlet.h>

Public Types
using	param_type = std::vector< float >
	The parameter type.
using	result_type = std::vector< float >
	The type for the samples generated.

Public Member Functions
Constructors / Destructors
	Dirichlet (const param_type &params)
	Default constructor.
	Dirichlet (const Dirichlet &from)
	Copy constructor.
	Dirichlet (Dirichlet &&from)
	Move constructor.
	~Dirichlet ()
	Class destructor.
Operators
Dirichlet &	operator= (const Dirichlet &from)
	Copy operator.
Dirichlet &	operator= (Dirichlet &&from)
	Move operator.
result_type	operator() ()
	Returns a sample from the Dirichlet distribution.
result_type	operator() (const param_type &p)
	Returns a sample from the Dirichlet distribution.
Accessors / Modifiers
const param_type &	param () const noexcept
	Returns the parameters of the distribution.
void	param (const param_type &p)
	Sets the parameters of the distribution.
float	min () const noexcept
	Returns the greatest lower bound of the range of values returned by gum::Dirichlet::operator()().
float	max () const noexcept
	Returns the lowest higher bound of the range of values returned by gum::Dirichlet::operator()().

Private Attributes
std::gamma_distribution< float >	_gamma_
	The gamma distribution used to compute the Dirichlet unnormalized samples.
param_type	_params_
	The parameters of the distribution.

Detailed Description

A class for sampling w.r.t.

Dirichlet distributions.

Definition at line 69 of file Dirichlet.h.

Member Typedef Documentation

param_type

using gum::Dirichlet::param_type = std::vector< float >

The parameter type.

Definition at line 72 of file Dirichlet.h.

result_type

using gum::Dirichlet::result_type = std::vector< float >

The type for the samples generated.

Definition at line 75 of file Dirichlet.h.

Constructor & Destructor Documentation

Dirichlet() [1/3]

INLINE gum::Dirichlet::Dirichlet

(

const param_type &

params

)

Default constructor.

Parameters

params	The distribution parameters.
seed	The distribution seed.

Definition at line 54 of file Dirichlet_inl.h.

                                                      : _params_(params) {
    GUM_CONSTRUCTOR(Dirichlet);
    for (const auto& a: params)
      if (a <= 0.0f) { GUM_ERROR(OutOfBounds, "Dirichlet: all alpha parameters must be > 0") }
  }

References Dirichlet(), _params_, and GUM_ERROR.

Referenced by Dirichlet(), Dirichlet(), Dirichlet(), ~Dirichlet(), operator=(), and operator=().

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Dirichlet() [2/3]

INLINE gum::Dirichlet::Dirichlet

(

const Dirichlet &

from

)

Copy constructor.

Parameters

from	The distribution to copy.

Definition at line 61 of file Dirichlet_inl.h.

                                                   :
      _gamma_(from._gamma_), _params_(from._params_) {
    GUM_CONS_CPY(Dirichlet);
  }

References Dirichlet(), _gamma_, and _params_.

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Dirichlet() [3/3]

INLINE gum::Dirichlet::Dirichlet

(

Dirichlet &&

from

)

Move constructor.

Parameters

from	The distribution to move.

Definition at line 67 of file Dirichlet_inl.h.

                                              :
      _gamma_(std::move(from._gamma_)), _params_(std::move(from._params_)) {
    GUM_CONS_MOV(Dirichlet);
  }

References Dirichlet(), _gamma_, and _params_.

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~Dirichlet()

INLINE gum::Dirichlet::~Dirichlet

(

)

Class destructor.

Definition at line 73 of file Dirichlet_inl.h.

{ GUM_DESTRUCTOR(Dirichlet); }

References Dirichlet().

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Member Function Documentation

max()

INLINE float gum::Dirichlet::max ( ) const

noexcept

Returns the lowest higher bound of the range of values returned by gum::Dirichlet::operator()().

Returns

Returns the lowest higher bound of the range of values returned by gum::Dirichlet::operator()().

Definition at line 145 of file Dirichlet_inl.h.

{ return 1.0f; }

min()

INLINE float gum::Dirichlet::min ( ) const

noexcept

Returns the greatest lower bound of the range of values returned by gum::Dirichlet::operator()().

Returns

Returns the greatest lower bound of the range of values returned by gum::Dirichlet::operator()().

Definition at line 142 of file Dirichlet_inl.h.

{ return 0.0f; }

operator()() [1/2]

INLINE Dirichlet::result_type gum::Dirichlet::operator()

(

)

Returns a sample from the Dirichlet distribution.

Returns

Returns a sample from the Dirichlet distribution.

Definition at line 94 of file Dirichlet_inl.h.

                                                    {
    Size        size = Size(_params_.size());
    result_type res(size);
    if (size == 0) return res;
    float sum = 0.0f;
    while (sum == 0.0f) {
      for (Idx i = 0; i < size; ++i) {
        _gamma_.param(std::gamma_distribution< float >::param_type(_params_[i], 1));
        res[i] = _gamma_(gum::randomGenerator());
        sum += res[i];
      }
    }
    for (Idx i = 0; i < size; ++i) {
      res[i] /= sum;
    }
    return res;
  }

References _gamma_, _params_, and gum::randomGenerator().

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operator()() [2/2]

INLINE Dirichlet::result_type gum::Dirichlet::operator()

(

const param_type &

p

)

Returns a sample from the Dirichlet distribution.

Parameters

p	An object representing the distribution's parameters, obtained by a call to gum::Dirichlet::param(const param_type&).

Definition at line 113 of file Dirichlet_inl.h.

                                                                                   {
    Size        size = Size(parm.size());
    result_type res(size);
    if (size == 0) return res;
    float sum = 0.0f;
    while (sum == 0.0f) {
      for (Idx i = 0; i < size; ++i) {
        _gamma_.param(std::gamma_distribution< float >::param_type(parm[i], 1));
        res[i] = _gamma_(gum::randomGenerator());
        sum += res[i];
      }
    }
    for (Idx i = 0; i < size; ++i) {
      res[i] /= sum;
    }
    return res;
  }

References _gamma_, and gum::randomGenerator().

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operator=() [1/2]

INLINE Dirichlet & gum::Dirichlet::operator=

(

const Dirichlet &

from

)

Copy operator.

Parameters

from	The distribution to copy.

Returns

Returns this gum::Dirichlet distribution.

Definition at line 76 of file Dirichlet_inl.h.

                                                            {
    if (&from != this) {
      _gamma_  = from._gamma_;
      _params_ = from._params_;
    }
    return *this;
  }

References Dirichlet(), _gamma_, and _params_.

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operator=() [2/2]

INLINE Dirichlet & gum::Dirichlet::operator=

(

Dirichlet &&

from

)

Move operator.

Parameters

from	The distribution to move.

Returns

Returns this gum::Dirichlet distribution.

Definition at line 85 of file Dirichlet_inl.h.

                                                       {
    if (&from != this) {
      _gamma_  = std::move(from._gamma_);
      _params_ = std::move(from._params_);
    }
    return *this;
  }

References Dirichlet(), _gamma_, and _params_.

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param() [1/2]

INLINE const Dirichlet::param_type & gum::Dirichlet::param ( ) const

noexcept

Returns the parameters of the distribution.

Returns

Returns the parameters of the distribution.

Definition at line 132 of file Dirichlet_inl.h.

{ return _params_; }

References _params_.

param() [2/2]

INLINE void gum::Dirichlet::param

(

const param_type &

p

)

Sets the parameters of the distribution.

Parameters

p	An object representing the distribution's parameters, obtained by a call to member function param.

Definition at line 135 of file Dirichlet_inl.h.

                                                              {
    for (const auto& a: parm)
      if (a <= 0.0f) { GUM_ERROR(OutOfBounds, "Dirichlet: all alpha parameters must be > 0") }
    _params_ = parm;
  }

References _params_, and GUM_ERROR.

Member Data Documentation

_gamma_

std::gamma_distribution< float > gum::Dirichlet::_gamma_

private

The gamma distribution used to compute the Dirichlet unnormalized samples.

Definition at line 179 of file Dirichlet.h.

Referenced by Dirichlet(), Dirichlet(), operator()(), operator()(), operator=(), and operator=().

_params_

param_type gum::Dirichlet::_params_

private

The parameters of the distribution.

Definition at line 182 of file Dirichlet.h.

Referenced by Dirichlet(), Dirichlet(), Dirichlet(), operator()(), operator=(), operator=(), param(), and param().

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The documentation for this class was generated from the following files:

• agrum/base/core/math/Dirichlet.h
• agrum/base/core/math/Dirichlet_inl.h