Detailed Description

This class can be used to convert a document collection contained in a CStringFeatures<char> object where each document is stored as a single vector into a hashed Bag-of-Words representation. Like in the standard Bag-of-Words representation, this class considers each document as a collection of tokens, which are then hashed into a new feature space of a specified dimension. This class is very flexible and allows the user to specify the tokenizer used to tokenize each document, specify whether the results should be normalized with regards to the sqrt of the document size, as well as to specify whether he wants to combine different tokens. The latter implements a k-skip n-grams approach, meaning that you can combine up to n tokens, while skipping up to k. Eg. for the tokens ["a", "b", "c", "d"], with n_grams = 2 and skips = 2, one would get the following combinations : ["a", "ab", "ac" (skipped 1), "ad" (skipped 2), "b", "bc", "bd" (skipped 1), "c", "cd", "d"].

Definition at line 37 of file HashedDocConverter.h.

Inheritance diagram for CHashedDocConverter:

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Public Member Functions
	CHashedDocConverter ()
	CHashedDocConverter (int32_t hash_bits, bool normalize=false, int32_t n_grams=1, int32_t skips=0)
	CHashedDocConverter (CTokenizer *tzer, int32_t hash_bits, bool normalize=false, int32_t n_grams=1, int32_t skips=0)
virtual	~CHashedDocConverter ()
virtual CFeatures *	apply (CFeatures *features)
SGSparseVector< float64_t >	apply (SGVector< char > document)
virtual const char *	get_name () const
void	set_normalization (bool normalize)
void	set_k_skip_n_grams (int32_t k, int32_t n)
virtual CSGObject *	shallow_copy () const
virtual CSGObject *	deep_copy () const
virtual bool	is_generic (EPrimitiveType *generic) const
template<class T >
void	set_generic ()
void	unset_generic ()
virtual void	print_serializable (const char *prefix="")
virtual bool	save_serializable (CSerializableFile file, const char prefix="", int32_t param_version=Version::get_version_parameter())
virtual bool	load_serializable (CSerializableFile file, const char prefix="", int32_t param_version=Version::get_version_parameter())
DynArray< TParameter * > *	load_file_parameters (const SGParamInfo param_info, int32_t file_version, CSerializableFile file, const char *prefix="")
DynArray< TParameter * > *	load_all_file_parameters (int32_t file_version, int32_t current_version, CSerializableFile file, const char prefix="")
void	map_parameters (DynArray< TParameter * > param_base, int32_t &base_version, DynArray< const SGParamInfo > *target_param_infos)
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)
virtual bool	update_parameter_hash ()
virtual bool	equals (CSGObject *other, float64_t accuracy=0.0)
virtual CSGObject *	clone ()

Static Public Member Functions
static void	generate_ngram_hashes (CDynamicArray< uint32_t > hashes, CDynamicArray< index_t > ngram_hashes, int32_t num_bits, int32_t ngrams, int32_t tokens_to_skip)

Public Attributes
SGIO *	io
Parallel *	parallel
Version *	version
Parameter *	m_parameters
Parameter *	m_model_selection_parameters
Parameter *	m_gradient_parameters
ParameterMap *	m_parameter_map
uint32_t	m_hash

Protected Member Functions
void	init (CTokenizer *tzer, int32_t d, bool normalize, int32_t n_grams, int32_t skips)
int32_t	count_distinct_indices (CDynamicArray< uint32_t > &hashed_indices)
SGSparseVector< float64_t >	create_hashed_representation (CDynamicArray< uint32_t > &hashed_indices)
virtual TParameter *	migrate (DynArray< TParameter * > param_base, const SGParamInfo target)
virtual void	one_to_one_migration_prepare (DynArray< TParameter * > param_base, const SGParamInfo target, TParameter &replacement, TParameter &to_migrate, char *old_name=NULL)
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)

Protected Attributes
int32_t	num_bits
CTokenizer *	tokenizer
bool	should_normalize
int32_t	ngrams
int32_t	tokens_to_skip

Constructor & Destructor Documentation

CHashedDocConverter ( )

Default constructor

Definition at line 24 of file HashedDocConverter.cpp.

CHashedDocConverter	(	int32_t	hash_bits,
		bool	normalize = `false`,
		int32_t	n_grams = `1`,
		int32_t	skips = `0`
	)

Constructor Creates tokens on whitespace

Parameters

hash_bits	the number of bits of the hash. Means a dimension of size 2^(hash_bits).
normalize	whether to normalize vectors or not
n_grams	the max number of tokens to consider when combining tokens
skips	the max number of tokens to skip when combining tokens

Definition at line 29 of file HashedDocConverter.cpp.

CHashedDocConverter	(	CTokenizer *	tzer,
		int32_t	hash_bits,
		bool	normalize = `false`,
		int32_t	n_grams = `1`,
		int32_t	skips = `0`
	)

Constructor

Parameters

tzer	the tokenizer to use
hash_bits	the number of bits of the hash. Means a dimension of size 2^(hash_bits).
normalize	whether to normalize vectors or not
n_grams	the max number of tokens to consider when combining tokens
skips	the max number of tokens to skip when combining tokens

Definition at line 35 of file HashedDocConverter.cpp.

~CHashedDocConverter ( )

virtual

Destructor

Definition at line 41 of file HashedDocConverter.cpp.

Member Function Documentation

CFeatures * apply ( CFeatures * features )

virtual

Hashes each string contained in features

Parameters

features the strings to be hashed. Must be an instance of CStringFeatures.

Returns: a CSparseFeatures object containing the hashes of the strings.

Implements CConverter.

Definition at line 82 of file HashedDocConverter.cpp.

SGSparseVector< float64_t > apply ( SGVector< char > document )

Hashes the tokens contained in document

Parameters

document the char vector to tokenize and hash

Returns: a SGSparseVector with the hashed representation of the document

Reading n+s-1 tokens

Reading token and storing index to hashed_indices

For remaining combinations

Normalizing vector

Definition at line 102 of file HashedDocConverter.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

dict	dictionary of parameters to be built.

Definition at line 1196 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 1313 of file SGObject.cpp.

int32_t count_distinct_indices ( CDynamicArray< uint32_t > & hashed_indices )

protected

This method takes a dynamic array as an argument, sorts it and returns the number of the distinct elements(indices here) in the array.

Parameters

hashed_indices the array to sort and count elements

Returns: the number of distinct elements

Counting nnz features

Definition at line 215 of file HashedDocConverter.cpp.

SGSparseVector< float64_t > create_hashed_representation ( CDynamicArray< uint32_t > & hashed_indices )

protected

This method takes the dynamic array containing all the hashed indices of a document and returns a compact sparse representation with each index found and with the count of such index

Parameters

hashed_indices the array containing the hashed indices

Returns: the compact hashed document representation

Definition at line 171 of file HashedDocConverter.cpp.

virtual CSGObject* deep_copy ( ) const

virtualinherited

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

Definition at line 160 of file SGObject.h.

bool equals	(	CSGObject *	other,
		float64_t	accuracy = `0.0`
	)

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

other	object to compare with
accuracy	accuracy to use for comparison (optional)

Returns: true if all parameters were equal, false if not

Definition at line 1217 of file SGObject.cpp.

void generate_ngram_hashes	(	CDynamicArray< uint32_t > *	hashes,
		CDynamicArray< index_t > *	ngram_hashes,
		int32_t	num_bits,
		int32_t	ngrams,
		int32_t	tokens_to_skip
	)

static

Generate all the k-skip ngram combinations for the tokens in the CDynArray hashes and then hash limit them to a specific dimension

Parameters

hashes	the hashes of the tokens to combine as k-skip ngrams
ngram_hashes	the dynamic array in which to store the created indices
num_bits	the dimension in which to limit the hashed indices (means a dimension of size 2^num_bits)
ngrams	the max number of tokens to combine
tokens_to_skip	the max number of tokens to skip when combining (starting always from the second one)

Returns: an array containing the hashed indices of the combined tokens

Definition at line 192 of file HashedDocConverter.cpp.

SGIO * get_global_io ( )

inherited

get the io object

Returns: io object

Definition at line 214 of file SGObject.cpp.

Parallel * get_global_parallel ( )

inherited

get the parallel object

Returns: parallel object

Definition at line 249 of file SGObject.cpp.

Version * get_global_version ( )

inherited

get the version object

Returns: version object

Definition at line 262 of file SGObject.cpp.

SGStringList< char > get_modelsel_names ( )

inherited

Returns: vector of names of all parameters which are registered for model selection

Definition at line 1100 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_name name of the parameter

Returns: description of the parameter

Definition at line 1124 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_name name of model selection parameter

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

Definition at line 1137 of file SGObject.cpp.

const char * get_name ( ) const

virtual

Returns: object name

Reimplemented from CConverter.

Definition at line 77 of file HashedDocConverter.cpp.

void init	(	CTokenizer *	tzer,
		int32_t	d,
		bool	normalize,
		int32_t	n_grams,
		int32_t	skips
	)

protected

init

Definition at line 46 of file HashedDocConverter.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

generic set to the type of the generic if returning TRUE

Returns: TRUE if a class template.

Definition at line 268 of file SGObject.cpp.

DynArray< TParameter * > * load_all_file_parameters	(	int32_t	file_version,
		int32_t	current_version,
		CSerializableFile *	file,
		const char *	prefix = `""`
	)

inherited

maps all parameters of this instance to the provided file version and loads all parameter data from the file into an array, which is sorted (basically calls load_file_parameter(...) for all parameters and puts all results into a sorted array)

Parameters

file_version	parameter version of the file
current_version	version from which mapping begins (you want to use Version::get_version_parameter() for this in most cases)
file	file to load from
prefix	prefix for members

Returns: (sorted) array of created TParameter instances with file data

Definition at line 673 of file SGObject.cpp.

DynArray< TParameter * > * load_file_parameters	(	const SGParamInfo *	param_info,
		int32_t	file_version,
		CSerializableFile *	file,
		const char *	prefix = `""`
	)

inherited

loads some specified parameters from a file with a specified version The provided parameter info has a version which is recursively mapped until the file parameter version is reached. Note that there may be possibly multiple parameters in the mapping, therefore, a set of TParameter instances is returned

Parameters

param_info	information of parameter
file_version	parameter version of the file, must be <= provided parameter version
file	file to load from
prefix	prefix for members

Returns: new array with TParameter instances with the attached data

Definition at line 514 of file SGObject.cpp.

bool load_serializable	(	CSerializableFile *	file,
		const char *	prefix = `""`,
		int32_t	param_version = `Version::get_version_parameter()`
	)

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

file	where to load from
prefix	prefix for members
param_version	(optional) a parameter version different to (this is mainly for testing, better do not use)

Returns: TRUE if done, otherwise FALSE

Definition at line 345 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

ShogunException Will be thrown if an error occurres.

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

Definition at line 1029 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

ShogunException Will be thrown if an error occurres.

Reimplemented in CDynamicArray< T >, CDynamicArray< float64_t >, CDynamicArray< float32_t >, CDynamicArray< int32_t >, CDynamicArray< char >, CDynamicArray< bool >, CDynamicArray< uint64_t >, and CDynamicObjectArray.

Definition at line 1024 of file SGObject.cpp.

void map_parameters	(	DynArray< TParameter * > *	param_base,
		int32_t &	base_version,
		DynArray< const SGParamInfo * > *	target_param_infos
	)

inherited

Takes a set of TParameter instances (base) with a certain version and a set of target parameter infos and recursively maps the base level wise to the current version using CSGObject::migrate(...). The base is replaced. After this call, the base version containing parameters should be of same version/type as the initial target parameter infos. Note for this to work, the migrate methods and all the internal parameter mappings have to match

Parameters

param_base	set of TParameter instances that are mapped to the provided target parameter infos
base_version	version of the parameter base
target_param_infos	set of SGParamInfo instances that specify the target parameter base

Definition at line 711 of file SGObject.cpp.

TParameter * migrate	(	DynArray< TParameter * > *	param_base,
		const SGParamInfo *	target
	)

protectedvirtualinherited

creates a new TParameter instance, which contains migrated data from the version that is provided. The provided parameter data base is used for migration, this base is a collection of all parameter data of the previous version. Migration is done FROM the data in param_base TO the provided param info Migration is always one version step. Method has to be implemented in subclasses, if no match is found, base method has to be called.

If there is an element in the param_base which equals the target, a copy of the element is returned. This represents the case when nothing has changed and therefore, the migrate method is not overloaded in a subclass

Parameters

param_base	set of TParameter instances to use for migration
target	parameter info for the resulting TParameter

Returns: a new TParameter instance with migrated data from the base of the type which is specified by the target parameter

Definition at line 918 of file SGObject.cpp.

void one_to_one_migration_prepare	(	DynArray< TParameter * > *	param_base,
		const SGParamInfo *	target,
		TParameter *&	replacement,
		TParameter *&	to_migrate,
		char *	old_name = `NULL`
	)

protectedvirtualinherited

This method prepares everything for a one-to-one parameter migration. One to one here means that only ONE element of the parameter base is needed for the migration (the one with the same name as the target). Data is allocated for the target (in the type as provided in the target SGParamInfo), and a corresponding new TParameter instance is written to replacement. The to_migrate pointer points to the single needed TParameter instance needed for migration. If a name change happened, the old name may be specified by old_name. In addition, the m_delete_data flag of to_migrate is set to true. So if you want to migrate data, the only thing to do after this call is converting the data in the m_parameter fields. If unsure how to use - have a look into an example for this. (base_migration_type_conversion.cpp for example)

Parameters

param_base	set of TParameter instances to use for migration
target	parameter info for the resulting TParameter
replacement	(used as output) here the TParameter instance which is returned by migration is created into
to_migrate	the only source that is used for migration
old_name	with this parameter, a name change may be specified

Definition at line 858 of file SGObject.cpp.

void print_modsel_params ( )

inherited

prints all parameter registered for model selection and their type

Definition at line 1076 of file SGObject.cpp.

void print_serializable ( const char * prefix = "" )

virtualinherited

prints registered parameters out

Parameters

prefix prefix for members

Definition at line 280 of file SGObject.cpp.

bool save_serializable	(	CSerializableFile *	file,
		const char *	prefix = `""`,
		int32_t	param_version = `Version::get_version_parameter()`
	)

virtualinherited

Save this object to file.

Parameters

file	where to save the object; will be closed during returning if PREFIX is an empty string.
prefix	prefix for members
param_version	(optional) a parameter version different to (this is mainly for testing, better do not use)

Returns: TRUE if done, otherwise FALSE

Definition at line 286 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

ShogunException Will be thrown if an error occurres.

Reimplemented in CKernel.

Definition at line 1039 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

ShogunException Will be thrown if an error occurres.

Reimplemented in CKernel, CDynamicArray< T >, CDynamicArray< float64_t >, CDynamicArray< float32_t >, CDynamicArray< int32_t >, CDynamicArray< char >, CDynamicArray< bool >, CDynamicArray< uint64_t >, and CDynamicObjectArray.

Definition at line 1034 of file SGObject.cpp.

void set_generic< complex128_t > ( )

inherited

set generic type to T

Definition at line 41 of file SGObject.cpp.

void set_global_io ( SGIO * io )

inherited

set the io object

Parameters

io	io object to use

Definition at line 207 of file SGObject.cpp.

void set_global_parallel ( Parallel * parallel )

inherited

set the parallel object

Parameters

parallel parallel object to use

Definition at line 220 of file SGObject.cpp.

void set_global_version ( Version * version )

inherited

set the version object

Parameters

version version object to use

Definition at line 255 of file SGObject.cpp.

void set_k_skip_n_grams	(	int32_t	k,
		int32_t	n
	)

Method used to specify the parameters for the quadratic approach of k-skip n-grams. See class description for more details and an example.

Parameters

k	the max number of allowed skips
n	the max number of tokens to combine

Definition at line 238 of file HashedDocConverter.cpp.

void set_normalization ( bool normalize )

specify whether hashed vector should be normalized or not

Parameters

normalize whether to normalize

Definition at line 233 of file HashedDocConverter.cpp.

virtual 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 151 of file SGObject.h.

void unset_generic ( )

inherited

unset generic type

this has to be called in classes specializing a template class

Definition at line 275 of file SGObject.cpp.

bool update_parameter_hash ( )

virtualinherited

Updates the hash of current parameter combination.

Returns: bool if parameter combination has changed since last update.

Definition at line 227 of file SGObject.cpp.

Member Data Documentation

SGIO* io

inherited

io

Definition at line 514 of file SGObject.h.

Parameter* m_gradient_parameters

inherited

parameters wrt which we can compute gradients

Definition at line 529 of file SGObject.h.

uint32_t m_hash

inherited

Hash of parameter values

Definition at line 535 of file SGObject.h.

Parameter* m_model_selection_parameters

inherited

model selection parameters

Definition at line 526 of file SGObject.h.

ParameterMap* m_parameter_map

inherited

map for different parameter versions

Definition at line 532 of file SGObject.h.

Parameter* m_parameters

inherited

parameters

Definition at line 523 of file SGObject.h.

int32_t ngrams

protected

the number of consecutives tokens for quadratic

Definition at line 144 of file HashedDocConverter.h.

int32_t num_bits

protected

the number of bits of the hash

Definition at line 135 of file HashedDocConverter.h.

Parallel* parallel

inherited

parallel

Definition at line 517 of file SGObject.h.

bool should_normalize

protected

whether to normalize or not

Definition at line 141 of file HashedDocConverter.h.

CTokenizer* tokenizer

protected

the tokenizer

Definition at line 138 of file HashedDocConverter.h.

int32_t tokens_to_skip

protected

the number of tokens to skip

Definition at line 147 of file HashedDocConverter.h.

Version* version

inherited

version

Definition at line 520 of file SGObject.h.

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

Detailed Description

Public Member Functions

Static Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation