itpp::Vector_Quantizer Class Reference

Class for vector quantization. More...

#include <itpp/srccode/vq.h>

Public Member Functions
	Vector_Quantizer ()
	Default constructor.
	Vector_Quantizer (const char *Name)
	Create a VQ from a VQ file.
int	encode (const vec &x)
	Encode the input vector.
ivec	encode (const vec &x, int num)
	Encode the input vector, and return the num best indices.
vec	decode (int Index) const
	Decode the index.
Array< vec >	decode (const ivec &Index) const
	Decode the indices.
vec	Q (const vec &x)
	Quantize the input vector.
vec	operator() (const vec &x)
	Quantize the input vector.
void	set_codebook (const mat &CB)
	Initialize the codebook by a matrix.
mat	get_codebook () const
	Returns the codebook.
void	set_codevector (int Index, const vec &indata)
	Set a codevector in the codebook.
vec	get_codevector (int Index) const
	Returns the codevector at the given index.
void	modify_codevector (int no, double mul, const vec &add)
	Rescale and translate a codevector.
int	size () const
	Returns the size (number of codevectors) of the VQ.
int	dim () const
	Returns the dimension of the VQ.
int	nobits () const
	Returns the number of bits of the VQ [log2(size)/dim].
void	load (const char *Name)
	Load the codebook from a file.
void	save (const char *Name) const
	Save the codebook to a file.
double	latest_distortion ()
	Returns the distortion at the latest time a vector was encoded.

Protected Attributes
vec	CodeBook
	The vector containing the code book.
int	Size
	The size of the code book.
int	Dim
	The dimension of the code book.
double	LatestDist
	The distortion at the latest time a vector was encoded.

Detailed Description

Class for vector quantization.

The following code illustrates how the VQ can be initialized from a file and used to quantize a random vector.

Vector_Quantizer Quantizer;
vec     x,y;
int     i;
 
Quantizer.load("randomvq.vq");
x=randn(Quantizer.dim());
i=Quantizer.encode(x);
y=Quantizer.decode(i);

Definition at line 62 of file vq.h.

Member Function Documentation

decode()

vec itpp::Vector_Quantizer::decode ( int  Index ) const

inline

Decode the index.

Definition at line 130 of file vq.h.

References get_codevector().

Referenced by Q().

Q()

vec itpp::Vector_Quantizer::Q ( const vec &  x )

inline

Quantize the input vector.

Definition at line 131 of file vq.h.

References decode(), and encode().

Referenced by operator()().

operator()()

vec itpp::Vector_Quantizer::operator() ( const vec &  x )

inline

Quantize the input vector.

Definition at line 132 of file vq.h.

References Q().

size()

int itpp::Vector_Quantizer::size ( ) const

inline

Returns the size (number of codevectors) of the VQ.

Definition at line 126 of file vq.h.

References Size.

dim()

int itpp::Vector_Quantizer::dim ( ) const

inline

Returns the dimension of the VQ.

Definition at line 128 of file vq.h.

References Dim.

nobits()

int itpp::Vector_Quantizer::nobits ( ) const

inline

Returns the number of bits of the VQ [log2(size)/dim].

Definition at line 127 of file vq.h.

References itpp::levels2bits(), and Size.

load()

void itpp::Vector_Quantizer::load

(

const char *

Name

)

Load the codebook from a file.

Parameters

Name	The name of the VQ file

The file format is a textfile where each row is a vector from the codebook.

save()

void itpp::Vector_Quantizer::save

(

const char *

Name

)

const

Save the codebook to a file.

Parameters

Name	The name of the VQ file

The file format is a textfile where each row is a vector from the codebook.

latest_distortion()

double itpp::Vector_Quantizer::latest_distortion ( )

inline

Returns the distortion at the latest time a vector was encoded.

Definition at line 129 of file vq.h.

References LatestDist.

Member Data Documentation

CodeBook

vec itpp::Vector_Quantizer::CodeBook

protected

The vector containing the code book.

Definition at line 115 of file vq.h.

Size

int itpp::Vector_Quantizer::Size

protected

The size of the code book.

Definition at line 117 of file vq.h.

Referenced by nobits(), and size().

Dim

int itpp::Vector_Quantizer::Dim

protected

The dimension of the code book.

Definition at line 119 of file vq.h.

Referenced by dim().

LatestDist

double itpp::Vector_Quantizer::LatestDist

protected

The distortion at the latest time a vector was encoded.

Definition at line 121 of file vq.h.

Referenced by latest_distortion().

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

• itpp/srccode/vq.h