A categorical distribution. More...

#include <prob_distribution.h>

Public Member Functions
	Categorical_distribution ()
	Construct an empty distribution. More...

	Categorical_distribution (const std::vector< double > &ps, const T &t1=T(1))
	Constructs a categorical distribution over the integers {t1, ..., t1 + K}, where K is the length of the given vector. More...

	Categorical_distribution (const Vector &ps, const T &=T(1))
	Constructs a categorical distribution over the integers {1, ..., K}, where K is the length of the given vector. More...

	Categorical_distribution (const std::vector< T > &values, const std::vector< double > &probabilities)
	Constructs a categorical distribution over a set of values. More...

	Categorical_distribution (const std::map< T, double > &d)
	Constructs a categorical distribution over a set of values. More...

	Categorical_distribution (const std::map< T, size_t > &m)
	Constructs an empirical distribution from a map of vals to counts. More...

	Categorical_distribution (const T &min, const T &max, const T &step)
	Constructs a categorical distribution limits. More...

	Categorical_distribution (const T &x1, const T &x2, double p1, double p2)
	Creates a two-element categorical distribution. More...

	Categorical_distribution (const Categorical_distribution< T > &cd)
	Copy-ctor: needed to make sure init_cdf_ gets called. More...

Categorical_distribution< T > &	operator= (const Categorical_distribution< T > &cd)
	Assignment: needed to make sure init_cdf_ gets called. More...

size_t	size () const
	Size of this distribution. More...

void	erase (const T &key)

void	remove (const T &key)

void	insert (const T &key, double weight=1.0)

void	add (const T &key, double weight=1.0)

	~Categorical_distribution ()

Static Public Member Functions
static Categorical_distribution< T >	construct_from_log_map (const std::map< T, double > &log_map)

Friends
template<class U >
double	pdf (const Categorical_distribution< U > &dist, const U &x)

template<class U >
double	cdf (const Categorical_distribution< U > &dist, const U &x)

template<class U >
U	sample (const Categorical_distribution< U > &dist)

Detailed Description

template<class T = int>
class kjb::Categorical_distribution< T >

A categorical distribution.

This class implements a categorical distribution. This is a discrete probability distribution that assigns a probability to each of a finite number of numbers. It stores an STL map that relates values with probabilities.

Template Parameters

T	The type over which the distribution is over. Must be be a RealType (i.e., a field).

Constructor & Destructor Documentation

template<class T = int>

kjb::Categorical_distribution< T >::Categorical_distribution ( )

inline

Construct an empty distribution.

template<class T>

kjb::Categorical_distribution< T >::Categorical_distribution	(	const std::vector< double > &	ps,
		const T &	t1 = `T(1)`
	)

Constructs a categorical distribution over the integers {t1, ..., t1 + K}, where K is the length of the given vector.

Parameters

ps	A std::vector of probabilities

template<class T>

kjb::Categorical_distribution< T >::Categorical_distribution	(	const Vector &	ps,
		const T &	t1 = `T(1)`
	)

Constructs a categorical distribution over the integers {1, ..., K}, where K is the length of the given vector.

Parameters

ps	A kjb::Vector of probabilities.

template<class T>

kjb::Categorical_distribution< T >::Categorical_distribution	(	const std::vector< T > &	values,
		const std::vector< double > &	probabilities
	)

Constructs a categorical distribution over a set of values.

Parameters

values	A set of values to define probabilities over
probabilities	The probabilities corresponding to the values.

template<class T = int>

kjb::Categorical_distribution< T >::Categorical_distribution ( const std::map< T, double > & d )

inline

Constructs a categorical distribution over a set of values.

Parameters

values_begin	Beginning of a sequence of values to define probabilities over
values_end	End of a sequence of values to define probabilities over
probabilities_begin	The beginning of a sequence of probabilities corresponding to the values.

Precondition: probability sequence has at least std::distance(values_begin, values_end) elements Constructs a categorical distribution from the given map.

Parameters

d	A map containing the distribution. It must be such that P(X = x) = d[x].

template<class T = int>

kjb::Categorical_distribution< T >::Categorical_distribution ( const std::map< T, size_t > & m )

inline

Constructs an empirical distribution from a map of vals to counts.

Parameters

m	A map containing the distribution. It must be such that P(X = x) is proportional to m[x].

template<class T>

kjb::Categorical_distribution< T >::Categorical_distribution	(	const T &	min,
		const T &	max,
		const T &	step
	)

Constructs a categorical distribution limits.

Creates a uniform distribution over the set {min, min + step, ..., max}, where each element has probability step / (max - min + 1).

Parameters

min	smallest element of the support
max	largest element of the support
step	gap between elements of the support

template<class T = int>

kjb::Categorical_distribution< T >::Categorical_distribution	(	const T &	x1,
		const T &	x2,
		double	p1,
		double	p2
	)

inline

Creates a two-element categorical distribution.

This constructore creates a two-element distribution, with P(X = x1) = p1 and P(X = x2) = p2. Remember that p1 + p2 = 1.

(wait, so this is just a bernoulli distribution? suggest removing this constructor –kyle, March 13, 2012)

template<class T = int>

kjb::Categorical_distribution< T >::Categorical_distribution ( const Categorical_distribution< T > & cd )

inline

Copy-ctor: needed to make sure init_cdf_ gets called.

template<class T = int>

kjb::Categorical_distribution< T >::~Categorical_distribution ( )

inline

Member Function Documentation

template<class T = int>

void kjb::Categorical_distribution< T >::add	(	const T &	key,
		double	weight = `1.0`
	)

inline

Alias of insert.

Deprecated in favor of the more STL-esque name, insert().

template<class T = int>

static Categorical_distribution<T> kjb::Categorical_distribution< T >::construct_from_log_map ( const std::map< T, double > & log_map )

inlinestatic

Named constructor

Similar to the constructor that recieves a map of value-weight pairs, but in this case, the weights are given in log-space.

This constructor converts to normalized non-log weights, without losing precision even when the unnormalized weights are extremely small.

Author: Kyle Simek

template<class T = int>

void kjb::Categorical_distribution< T >::erase ( const T & key )

inline

Parameters

weight Remove an item from the collection.

Cumulative distrbution will be re-constructed from scratch, requiring O(n) time.

Exceptions

Illegal_argument if key does not exist in the collection.

template<class T = int>

void kjb::Categorical_distribution< T >::insert	(	const T &	key,
		double	weight = `1.0`
	)

inline

Parameters

weight Unnormalized weight of new atom. This is added to the total of atom weights, and the normalization constant is updated.

Running time is O(log n)

template<class T = int>

Categorical_distribution<T>& kjb::Categorical_distribution< T >::operator= ( const Categorical_distribution< T > & cd )

inline

Assignment: needed to make sure init_cdf_ gets called.

template<class T = int>

void kjb::Categorical_distribution< T >::remove ( const T & key )

inline

Alias of erase().

Deprecated in favor of the more STL-esque erase().

template<class T = int>

size_t kjb::Categorical_distribution< T >::size ( ) const

inline

Size of this distribution.

Returns the size of the support of this distribution

Friends And Related Function Documentation

template<class T = int>

template<class U >

double cdf	(	const Categorical_distribution< U > &	dist,
		const U &	x
	)

friend

template<class T = int>

template<class U >

double pdf	(	const Categorical_distribution< U > &	dist,
		const U &	x
	)

friend

template<class T = int>

template<class U >

U sample ( const Categorical_distribution< U > & dist )

friend

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

/work/kobus/src/lib/prob_cpp/prob_distribution.h

Public Member Functions

Static Public Member Functions

Friends

Detailed Description

template<class T = int> class kjb::Categorical_distribution< T >

Constructor & Destructor Documentation

Member Function Documentation

Friends And Related Function Documentation

template<class T = int>
class kjb::Categorical_distribution< T >