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CMultidimensionalScaling Class Reference

Detailed Description

class Multidimensionalscaling is used to perform multidimensional scaling (capable of landmark approximation if requested).

Description of classical embedding is given on p.261 (Section 12.1) of Borg, I., & Groenen, P. J. F. (2005). Modern multidimensional scaling: Theory and applications. Springer.

Description of landmark MDS approximation is given in

Sparse multidimensional scaling using landmark points V De Silva, J B Tenenbaum (2004) Technology, p. 1-4

Note that target dimension should be set with reasonable value (using set_target_dim). In case it is higher than intrinsic dimensionality of the dataset 'extra' features of the output might be inconsistent (essentially, according to zero or negative eigenvalues). In this case a warning is fired.

It is possible to apply multidimensional scaling to any given distance using apply_to_distance_matrix method. By default euclidean distance is used (with parallel instance replaced by preprocessor's one).

Faster landmark approximation is parallel using posix threads. As for choice of landmark number it should be at least 3 for proper triangulation. For reasonable embedding accuracy greater values (30%-50% of total examples number) is pretty good for the most tasks.

Uses implementation from the Tapkee library.

To use this converter with static interfaces please refer it by sg('create_converter','mds');

Definition at line 60 of file MultidimensionalScaling.h.

Inheritance diagram for CMultidimensionalScaling:
[legend]

Public Member Functions

 CMultidimensionalScaling ()
 
virtual ~CMultidimensionalScaling ()
 
virtual CDenseFeatures
< float64_t > * 		embed_distance (CDistance *distance)
 
virtual CFeatures * apply (CFeatures *features)
 
const char * get_name () const
 
SGVector< float64_t > get_eigenvalues () const
 
void set_landmark_number (int32_t num)
 
int32_t get_landmark_number () const
 
void set_landmark (bool landmark)
 
bool get_landmark () const
 
virtual CDenseFeatures
< float64_t > * 		embed (CFeatures *features)
 
void set_target_dim (int32_t dim)
 
int32_t get_target_dim () const
 
void set_distance (CDistance *distance)
 
CDistance * get_distance () const
 
void set_kernel (CKernel *kernel)
 
CKernel * get_kernel () const
 
virtual CSGObject * shallow_copy () const
 
virtual CSGObject * deep_copy () const
 
virtual bool is_generic (EPrimitiveType *generic) const
 
template<class T >
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
template<>
void set_generic ()
 
void unset_generic ()
 
virtual void print_serializable (const char *prefix="")
 
virtual bool save_serializable (CSerializableFile *file, const char *prefix="")
 
virtual bool load_serializable (CSerializableFile *file, const char *prefix="")
 
void set_global_io (SGIO *io)
 
SGIO * get_global_io ()
 
void set_global_parallel (Parallel *parallel)
 
Parallel * get_global_parallel ()
 
void set_global_version (Version *version)
 
Version * get_global_version ()
 
SGStringList< char > get_modelsel_names ()
 
void print_modsel_params ()
 
char * get_modsel_param_descr (const char *param_name)
 
index_t get_modsel_param_index (const char *param_name)
 
void build_gradient_parameter_dictionary (CMap< TParameter *, CSGObject * > *dict)
 
bool has (const std::string &name) const
 
template<typename T >
bool has (const Tag< T > &tag) const
 
template<typename T , typename U = void>
bool has (const std::string &name) const
 
template<typename T >
void set (const Tag< T > &_tag, const T &value)
 
template<typename T , typename U = void>
void set (const std::string &name, const T &value)
 
template<typename T >
T get (const Tag< T > &_tag) const
 
template<typename T , typename U = void>
T get (const std::string &name) const
 
virtual void update_parameter_hash ()
 
virtual bool parameter_hash_changed ()
 
virtual bool equals (CSGObject *other, float64_t accuracy=0.0, bool tolerant=false)
 
virtual CSGObject * clone ()
 

Public Attributes

SGIO * io
 
Parallel * parallel
 
Version * version
 
Parameter * m_parameters
 
Parameter * m_model_selection_parameters
 
Parameter * m_gradient_parameters
 
uint32_t m_hash
 

Protected Member Functions

virtual void init ()
 HELPERS. More...
 
virtual void load_serializable_pre () throw (ShogunException)
 
virtual void load_serializable_post () throw (ShogunException)
 
virtual void save_serializable_pre () throw (ShogunException)
 
virtual void save_serializable_post () throw (ShogunException)
 
template<typename T >
void register_param (Tag< T > &_tag, const T &value)
 
template<typename T >
void register_param (const std::string &name, const T &value)
 

Protected Attributes

SGVector< float64_t > m_eigenvalues
 FIELDS. More...
 
bool m_landmark
 
int32_t m_landmark_number
 
int32_t m_target_dim
 
CDistance * m_distance
 
CKernel * m_kernel
 

Constructor & Destructor Documentation

CMultidimensionalScaling ( )

Definition at line 24 of file MultidimensionalScaling.cpp.

~CMultidimensionalScaling ( )
virtual

Definition at line 43 of file MultidimensionalScaling.cpp.

Member Function Documentation

CFeatures * apply ( CFeatures *  features)
virtual

apply preprocessor to feature matrix, changes feature matrix to the one having target dimensionality

Parameters
featuresfeatures which feature matrix should be processed
Returns
new feature matrix

Implements CEmbeddingConverter.

Definition at line 102 of file MultidimensionalScaling.cpp.

void build_gradient_parameter_dictionary ( CMap< TParameter *, CSGObject * > *  dict)
inherited

Builds a dictionary of all parameters in SGObject as well of those of SGObjects that are parameters of this object. Dictionary maps parameters to the objects that own them.

Parameters
dictdictionary of parameters to be built.

Definition at line 630 of file SGObject.cpp.

CSGObject * clone ( )
virtualinherited

Creates a clone of the current object. This is done via recursively traversing all parameters, which corresponds to a deep copy. Calling equals on the cloned object always returns true although none of the memory of both objects overlaps.

Returns
an identical copy of the given object, which is disjoint in memory. NULL if the clone fails. Note that the returned object is SG_REF'ed

Definition at line 747 of file SGObject.cpp.

CSGObject * deep_copy ( ) const
virtualinherited

A deep copy. All the instance variables will also be copied.

Definition at line 231 of file SGObject.cpp.

CDenseFeatures< float64_t > * embed ( CFeatures *  features)
virtualinherited

embed given features, acts the same as apply, but returns DenseFeatures

Parameters
featuresfeatures to embed
Returns
embedding simple features

Definition at line 35 of file EmbeddingConverter.cpp.

CDenseFeatures< float64_t > * embed_distance ( CDistance *  distance)
virtual

apply preprocessor to CDistance

Parameters
distance(should be approximate euclidean for consistent result)
Returns
new features with distance similar to given as much as possible

Reimplemented in CIsomap.

Definition at line 80 of file MultidimensionalScaling.cpp.

bool equals ( CSGObject *  other,
float64_t  accuracy = 0.0,
bool  tolerant = false 
)
virtualinherited

Recursively compares the current SGObject to another one. Compares all registered numerical parameters, recursion upon complex (SGObject) parameters. Does not compare pointers!

May be overwritten but please do with care! Should not be necessary in most cases.

Parameters
otherobject to compare with
accuracyaccuracy to use for comparison (optional)
tolerantallows linient check on float equality (within accuracy)
Returns
true if all parameters were equal, false if not

Definition at line 651 of file SGObject.cpp.

T get ( const Tag< T > &  _tag) const
inherited

Getter for a class parameter, identified by a Tag. Throws an exception if the class does not have such a parameter.

Parameters
_tagname and type information of parameter
Returns
value of the parameter identified by the input tag

Definition at line 367 of file SGObject.h.

T get ( const std::string &  name) const
inherited

Getter for a class parameter, identified by a name. Throws an exception if the class does not have such a parameter.

Parameters
namename of the parameter
Returns
value of the parameter corresponding to the input name and type

Definition at line 388 of file SGObject.h.

CDistance * get_distance ( ) const
inherited

getter for distance

Returns
distance

Definition at line 58 of file EmbeddingConverter.cpp.

SGVector< float64_t > get_eigenvalues ( ) const

get last embedding eigenvectors

Returns
vector with last eigenvalues

Definition at line 47 of file MultidimensionalScaling.cpp.

SGIO * get_global_io ( )
inherited

get the io object

Returns
io object

Definition at line 268 of file SGObject.cpp.

Parallel * get_global_parallel ( )
inherited

get the parallel object

Returns
parallel object

Definition at line 310 of file SGObject.cpp.

Version * get_global_version ( )
inherited

get the version object

Returns
version object

Definition at line 323 of file SGObject.cpp.

CKernel * get_kernel ( ) const
inherited

getter for kernel

Returns
kernel

Definition at line 71 of file EmbeddingConverter.cpp.

bool get_landmark ( ) const

getter for landmark parameter

Returns
true if landmark embedding is used

Definition at line 70 of file MultidimensionalScaling.cpp.

int32_t get_landmark_number ( ) const

get number of landmarks

Returns
current number of landmarks

Definition at line 60 of file MultidimensionalScaling.cpp.

SGStringList< char > get_modelsel_names ( )
inherited
Returns
vector of names of all parameters which are registered for model selection

Definition at line 531 of file SGObject.cpp.

char * get_modsel_param_descr ( const char *  param_name)
inherited

Returns description of a given parameter string, if it exists. SG_ERROR otherwise

Parameters
param_namename of the parameter
Returns
description of the parameter

Definition at line 555 of file SGObject.cpp.

index_t get_modsel_param_index ( const char *  param_name)
inherited

Returns index of model selection parameter with provided index

Parameters
param_namename of model selection parameter
Returns
index of model selection parameter with provided name, -1 if there is no such

Definition at line 568 of file SGObject.cpp.

const char * get_name ( ) const
virtual

get name

Reimplemented from CEmbeddingConverter.

Definition at line 75 of file MultidimensionalScaling.cpp.

int32_t get_target_dim ( ) const
inherited

getter for target dimension

Returns
target dimension

Definition at line 46 of file EmbeddingConverter.cpp.

bool has ( const std::string &  name) const
inherited

Checks if object has a class parameter identified by a name.

Parameters
namename of the parameter
Returns
true if the parameter exists with the input name

Definition at line 289 of file SGObject.h.

bool has ( const Tag< T > &  tag) const
inherited

Checks if object has a class parameter identified by a Tag.

Parameters
tagtag of the parameter containing name and type information
Returns
true if the parameter exists with the input tag

Definition at line 301 of file SGObject.h.

bool has ( const std::string &  name) const
inherited

Checks if a type exists for a class parameter identified by a name.

Parameters
namename of the parameter
Returns
true if the parameter exists with the input name and type

Definition at line 312 of file SGObject.h.

void init ( )
protectedvirtual

HELPERS.

default initialization

Reimplemented in CIsomap.

Definition at line 33 of file MultidimensionalScaling.cpp.

bool is_generic ( EPrimitiveType *  generic) const
virtualinherited

If the SGSerializable is a class template then TRUE will be returned and GENERIC is set to the type of the generic.

Parameters
genericset to the type of the generic if returning TRUE
Returns
TRUE if a class template.

Definition at line 329 of file SGObject.cpp.

bool load_serializable ( CSerializableFile *  file,
const char *  prefix = "" 
)
virtualinherited

Load this object from file. If it will fail (returning FALSE) then this object will contain inconsistent data and should not be used!

Parameters
filewhere to load from
prefixprefix for members
Returns
TRUE if done, otherwise FALSE

Definition at line 402 of file SGObject.cpp.

void load_serializable_post ( )
throw (ShogunException
)
protectedvirtualinherited

Can (optionally) be overridden to post-initialize some member variables which are not PARAMETER::ADD'ed. Make sure that at first the overridden method BASE_CLASS::LOAD_SERIALIZABLE_POST is called.

Exceptions
ShogunExceptionwill be thrown if an error occurs.

Reimplemented in CKernel, CWeightedDegreePositionStringKernel, CList, CAlphabet, CLinearHMM, CGaussianKernel, CInverseMultiQuadricKernel, CCircularKernel, and CExponentialKernel.

Definition at line 459 of file SGObject.cpp.

void load_serializable_pre ( )
throw (ShogunException
)
protectedvirtualinherited

Can (optionally) be overridden to pre-initialize some member variables which are not PARAMETER::ADD'ed. Make sure that at first the overridden method BASE_CLASS::LOAD_SERIALIZABLE_PRE is called.

Exceptions
ShogunExceptionwill be thrown if an error occurs.

Reimplemented in CDynamicArray< T >, CDynamicArray< float64_t >, CDynamicArray< float32_t >, CDynamicArray< int32_t >, CDynamicArray< char >, CDynamicArray< bool >, and CDynamicObjectArray.

Definition at line 454 of file SGObject.cpp.

bool parameter_hash_changed ( )
virtualinherited
Returns
whether parameter combination has changed since last update

Definition at line 295 of file SGObject.cpp.

void print_modsel_params ( )
inherited

prints all parameter registered for model selection and their type

Definition at line 507 of file SGObject.cpp.

void print_serializable ( const char *  prefix = "")
virtualinherited

prints registered parameters out

Parameters
prefixprefix for members

Definition at line 341 of file SGObject.cpp.

void register_param ( Tag< T > &  _tag,
const T &  value 
)
protectedinherited

Registers a class parameter which is identified by a tag. This enables the parameter to be modified by set() and retrieved by get(). Parameters can be registered in the constructor of the class.

Parameters
_tagname and type information of parameter
valuevalue of the parameter

Definition at line 439 of file SGObject.h.

void register_param ( const std::string &  name,
const T &  value 
)
protectedinherited

Registers a class parameter which is identified by a name. This enables the parameter to be modified by set() and retrieved by get(). Parameters can be registered in the constructor of the class.

Parameters
namename of the parameter
valuevalue of the parameter along with type information

Definition at line 452 of file SGObject.h.

bool save_serializable ( CSerializableFile *  file,
const char *  prefix = "" 
)
virtualinherited

Save this object to file.

Parameters
filewhere to save the object; will be closed during returning if PREFIX is an empty string.
prefixprefix for members
Returns
TRUE if done, otherwise FALSE

Definition at line 347 of file SGObject.cpp.

void save_serializable_post ( )
throw (ShogunException
)
protectedvirtualinherited

Can (optionally) be overridden to post-initialize some member variables which are not PARAMETER::ADD'ed. Make sure that at first the overridden method BASE_CLASS::SAVE_SERIALIZABLE_POST is called.

Exceptions
ShogunExceptionwill be thrown if an error occurs.

Reimplemented in CKernel.

Definition at line 469 of file SGObject.cpp.

void save_serializable_pre ( )
throw (ShogunException
)
protectedvirtualinherited

Can (optionally) be overridden to pre-initialize some member variables which are not PARAMETER::ADD'ed. Make sure that at first the overridden method BASE_CLASS::SAVE_SERIALIZABLE_PRE is called.

Exceptions
ShogunExceptionwill be thrown if an error occurs.

Reimplemented in CKernel, CDynamicArray< T >, CDynamicArray< float64_t >, CDynamicArray< float32_t >, CDynamicArray< int32_t >, CDynamicArray< char >, CDynamicArray< bool >, and CDynamicObjectArray.

Definition at line 464 of file SGObject.cpp.

void set ( const Tag< T > &  _tag,
const T &  value 
)
inherited

Setter for a class parameter, identified by a Tag. Throws an exception if the class does not have such a parameter.

Parameters
_tagname and type information of parameter
valuevalue of the parameter

Definition at line 328 of file SGObject.h.

void set ( const std::string &  name,
const T &  value 
)
inherited

Setter for a class parameter, identified by a name. Throws an exception if the class does not have such a parameter.

Parameters
namename of the parameter
valuevalue of the parameter along with type information

Definition at line 354 of file SGObject.h.

void set_distance ( CDistance *  distance)
inherited

setter for distance

Parameters
distancedistance to set

Definition at line 51 of file EmbeddingConverter.cpp.

void set_generic ( )
inherited

Definition at line 74 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 79 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 84 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 89 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 94 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 99 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 104 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 109 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 114 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 119 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 124 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 129 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 134 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 139 of file SGObject.cpp.

void set_generic ( )
inherited

Definition at line 144 of file SGObject.cpp.

void set_generic ( )
inherited

set generic type to T

void set_global_io ( SGIO *  io)
inherited

set the io object

Parameters
ioio object to use

Definition at line 261 of file SGObject.cpp.

void set_global_parallel ( Parallel *  parallel)
inherited

set the parallel object

Parameters
parallelparallel object to use

Definition at line 274 of file SGObject.cpp.

void set_global_version ( Version *  version)
inherited

set the version object

Parameters
versionversion object to use

Definition at line 316 of file SGObject.cpp.

void set_kernel ( CKernel *  kernel)
inherited

setter for kernel

Parameters
kernelkernel to set

Definition at line 64 of file EmbeddingConverter.cpp.

void set_landmark ( bool  landmark)

setter for landmark parameter

Parameters
landmarktrue if landmark embedding should be used

Definition at line 65 of file MultidimensionalScaling.cpp.

void set_landmark_number ( int32_t  num)

set number of landmarks should be lesser than number of examples and greater than 3 for consistent embedding as triangulation is used

Parameters
numnumber of landmark to be set

Definition at line 52 of file MultidimensionalScaling.cpp.

void set_target_dim ( int32_t  dim)
inherited

setter for target dimension

Parameters
dimtarget dimension

Definition at line 40 of file EmbeddingConverter.cpp.

CSGObject * shallow_copy ( ) const
virtualinherited

A shallow copy. All the SGObject instance variables will be simply assigned and SG_REF-ed.

Reimplemented in CGaussianKernel.

Definition at line 225 of file SGObject.cpp.

void unset_generic ( )
inherited

unset generic type

this has to be called in classes specializing a template class

Definition at line 336 of file SGObject.cpp.

void update_parameter_hash ( )
virtualinherited

Updates the hash of current parameter combination

Definition at line 281 of file SGObject.cpp.

Member Data Documentation

SGIO* io
inherited

io

Definition at line 537 of file SGObject.h.

CDistance* m_distance
protectedinherited

distance to be used

Definition at line 99 of file EmbeddingConverter.h.

SGVector<float64_t> m_eigenvalues
protected

FIELDS.

last embedding eigenvalues

Definition at line 123 of file MultidimensionalScaling.h.

Parameter* m_gradient_parameters
inherited

parameters wrt which we can compute gradients

Definition at line 552 of file SGObject.h.

uint32_t m_hash
inherited

Hash of parameter values

Definition at line 555 of file SGObject.h.

CKernel* m_kernel
protectedinherited

kernel to be used

Definition at line 102 of file EmbeddingConverter.h.

bool m_landmark
protected

use landmark approximation?

Definition at line 126 of file MultidimensionalScaling.h.

int32_t m_landmark_number
protected

number of landmarks

Definition at line 129 of file MultidimensionalScaling.h.

Parameter* m_model_selection_parameters
inherited

model selection parameters

Definition at line 549 of file SGObject.h.

Parameter* m_parameters
inherited

parameters

Definition at line 546 of file SGObject.h.

int32_t m_target_dim
protectedinherited

target dim of dimensionality reduction preprocessor

Definition at line 96 of file EmbeddingConverter.h.

Parallel* parallel
inherited

parallel

Definition at line 540 of file SGObject.h.

Version* version
inherited

version

Definition at line 543 of file SGObject.h.

The documentation for this class was generated from the following files:
SHOGUN Machine Learning Toolbox - Documentation