Detailed Description

LocalTangentSpaceAlignment used to embed data using Local Tangent Space Alignment (LTSA) algorithm as described in:

Zhang, Z., & Zha, H. (2002). Principal Manifolds and Nonlinear Dimension Reduction via Local Tangent Space Alignment. Journal of Shanghai University English Edition, 8(4), 406-424. SIAM. Retrieved from http://arxiv.org/abs/cs/0212008

Due to performance reasons on high-dimensional datasets please use KernelLocalTangentSpaceAlignment with linear kernel.

The stated eigenproblem is solved in the same way as CLocallyLinearEmbedding (LAPACK or ARPACK if available).

The local tangent space alignment step is parallel. Neighborhood determination is parallel as in CLocallyLinearEmbedding.

This algorithm is pretty stable for variations of k parameter value but be sure it is set with a consistent value (at least 3-5) for reasonable results.

Please do not use multithreading whether your LAPACK is not thread-safe.

Definition at line 50 of file LocalTangentSpaceAlignment.h.

Inheritance diagram for CLocalTangentSpaceAlignment:

[legend]

Public Member Functions
	CLocalTangentSpaceAlignment ()
virtual	~CLocalTangentSpaceAlignment ()
virtual const char *	get_name () const
Public Member Functions inherited from CLocallyLinearEmbedding
	CLocallyLinearEmbedding ()
virtual	~CLocallyLinearEmbedding ()
virtual CFeatures *	apply (CFeatures *features)
void	set_k (int32_t k)
int32_t	get_k () const
void	set_max_k (int32_t max_k)
int32_t	get_max_k () const
void	set_auto_k (bool auto_k)
bool	get_auto_k () const
void	set_reconstruction_shift (float64_t reconstruction_shift)
float64_t	get_reconstruction_shift () const
void	set_nullspace_shift (float64_t nullspace_shift)
float64_t	get_nullspace_shift () const
void	set_use_arpack (bool use_arpack)
bool	get_use_arpack () const
Public Member Functions inherited from CEmbeddingConverter
	CEmbeddingConverter ()
virtual	~CEmbeddingConverter ()
virtual CSimpleFeatures < 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
Public Member Functions inherited from CConverter
	CConverter ()
virtual	~CConverter ()
Public Member Functions inherited from CSGObject
	CSGObject ()
	CSGObject (const CSGObject &orig)
virtual	~CSGObject ()
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="")
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 ()
SGVector< char * >	get_modelsel_names ()
char *	get_modsel_param_descr (const char *param_name)
index_t	get_modsel_param_index (const char *param_name)

Protected Member Functions
virtual SGMatrix< float64_t >	construct_weight_matrix (CSimpleFeatures< float64_t > simple_features, float64_t W_matrix, SGMatrix< int32_t > neighborhood_matrix)
	HELPER.
Protected Member Functions inherited from CLocallyLinearEmbedding
void	init ()
	HELPERS.
virtual SGMatrix< float64_t >	construct_embedding (SGMatrix< float64_t > matrix, int dimension)
virtual SGMatrix< int32_t >	get_neighborhood_matrix (SGMatrix< float64_t > distance_matrix, int32_t k)
int32_t	estimate_k (CSimpleFeatures< float64_t > *simple_features, SGMatrix< int32_t > neighborhood_matrix)
float64_t	compute_reconstruction_error (int32_t k, int dim, int N, float64_t feature_matrix, float64_t z_matrix, float64_t covariance_matrix, float64_t resid_vector, float64_t *id_vector, SGMatrix< int32_t > neighborhood_matrix)

Static Protected Member Functions
static void *	run_ltsa_thread (void *p)
	THREAD.
Static Protected Member Functions inherited from CLocallyLinearEmbedding
static void *	run_neighborhood_thread (void *p)
	THREADS.
static void *	run_linearreconstruction_thread (void *p)

Additional Inherited Members
Public Attributes inherited from CSGObject
SGIO *	io
Parallel *	parallel
Version *	version
Parameter *	m_parameters
Parameter *	m_model_selection_parameters
Protected Attributes inherited from CLocallyLinearEmbedding
int32_t	m_k
	FIELDS.
int32_t	m_max_k
float64_t	m_reconstruction_shift
float64_t	m_nullspace_shift
bool	m_use_arpack
bool	m_auto_k

Constructor & Destructor Documentation

CLocalTangentSpaceAlignment ( )

constructor

Definition at line 67 of file LocalTangentSpaceAlignment.cpp.

~CLocalTangentSpaceAlignment ( )

virtual

destructor

Definition at line 72 of file LocalTangentSpaceAlignment.cpp.

Member Function Documentation

SGMatrix< float64_t > construct_weight_matrix	(	CSimpleFeatures< float64_t > *	simple_features,
		float64_t *	W_matrix,
		SGMatrix< int32_t >	neighborhood_matrix
	)