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CGaussianKernel Class Reference

Detailed Description

The well known Gaussian kernel (swiss army knife for SVMs) computed on CDotFeatures.

It is computed as

\[ k({\bf x},{\bf x'})= exp(-\frac{||{\bf x}-{\bf x'}||^2}{\tau}) \]

where $\tau$ is the kernel width.

The compact version as given in Bart Hamers' thesis Kernel Models for Large Scale Applications (Eq. 4.10) is computed as

\[ k({\bf x},{\bf x'})= max(0, (1-\frac{||{\bf x}-{\bf x'}||}{3\tau})^v)) * exp(-\frac{||{\bf x}-{\bf x'}||^2}{\tau}) \]

where $\tau$ is the kernel width.

Definition at line 44 of file GaussianKernel.h.

Inheritance diagram for CGaussianKernel:
Inheritance graph
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Public Member Functions

 CGaussianKernel ()
 CGaussianKernel (int32_t size, float64_t width)
 CGaussianKernel (CDotFeatures *l, CDotFeatures *r, float64_t width, int32_t size=10)
virtual ~CGaussianKernel ()
virtual bool init (CFeatures *l, CFeatures *r)
virtual void cleanup ()
virtual EKernelType get_kernel_type ()
virtual const char * get_name () const
virtual void set_width (float64_t w)
virtual float64_t get_width () const
void set_compact_enabled (bool compact)
bool get_compact_enabled ()
- Public Member Functions inherited from CDotKernel
 CDotKernel ()
 CDotKernel (int32_t cachesize)
 CDotKernel (CFeatures *l, CFeatures *r)
virtual EFeatureClass get_feature_class ()
virtual EFeatureType get_feature_type ()
- Public Member Functions inherited from CKernel
 CKernel ()
 CKernel (int32_t size)
 CKernel (CFeatures *l, CFeatures *r, int32_t size)
virtual ~CKernel ()
float64_t kernel (int32_t idx_a, int32_t idx_b)
SGMatrix< float64_tget_kernel_matrix ()
virtual SGVector< float64_tget_kernel_col (int32_t j)
virtual SGVector< float64_tget_kernel_row (int32_t i)
template<class T >
SGMatrix< T > get_kernel_matrix ()
virtual bool set_normalizer (CKernelNormalizer *normalizer)
virtual CKernelNormalizerget_normalizer ()
virtual bool init_normalizer ()
void load (CFile *loader)
void save (CFile *writer)
CFeaturesget_lhs ()
CFeaturesget_rhs ()
virtual int32_t get_num_vec_lhs ()
virtual int32_t get_num_vec_rhs ()
virtual bool has_features ()
bool get_lhs_equals_rhs ()
virtual void remove_lhs_and_rhs ()
virtual void remove_lhs ()
virtual void remove_rhs ()
 takes all necessary steps if the rhs is removed from kernel
void set_cache_size (int32_t size)
int32_t get_cache_size ()
void list_kernel ()
bool has_property (EKernelProperty p)
virtual void clear_normal ()
virtual void add_to_normal (int32_t vector_idx, float64_t weight)
EOptimizationType get_optimization_type ()
virtual void set_optimization_type (EOptimizationType t)
bool get_is_initialized ()
virtual bool init_optimization (int32_t count, int32_t *IDX, float64_t *weights)
virtual bool delete_optimization ()
bool init_optimization_svm (CSVM *svm)
virtual float64_t compute_optimized (int32_t vector_idx)
virtual void compute_batch (int32_t num_vec, int32_t *vec_idx, float64_t *target, int32_t num_suppvec, int32_t *IDX, float64_t *alphas, float64_t factor=1.0)
float64_t get_combined_kernel_weight ()
void set_combined_kernel_weight (float64_t nw)
virtual int32_t get_num_subkernels ()
virtual void compute_by_subkernel (int32_t vector_idx, float64_t *subkernel_contrib)
virtual const float64_tget_subkernel_weights (int32_t &num_weights)
virtual void set_subkernel_weights (SGVector< float64_t > weights)
- 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)
SGIOget_global_io ()
void set_global_parallel (Parallel *parallel)
Parallelget_global_parallel ()
void set_global_version (Version *version)
Versionget_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 float64_t compute (int32_t idx_a, int32_t idx_b)
virtual void load_serializable_post () throw (ShogunException)

Protected Attributes

float64_t width
float64_tsq_lhs
float64_tsq_rhs
bool m_compact

Additional Inherited Members

- Public Attributes inherited from CSGObject
SGIOio
Parallelparallel
Versionversion
Parameterm_parameters
Parameterm_model_selection_parameters
- Static Protected Member Functions inherited from CKernel
template<class T >
static void * get_kernel_matrix_helper (void *p)

Constructor & Destructor Documentation

default constructor

Definition at line 22 of file GaussianKernel.cpp.

CGaussianKernel ( int32_t  size,
float64_t  width 
)

constructor

Parameters
sizecache size
widthwidth

Definition at line 28 of file GaussianKernel.cpp.

CGaussianKernel ( CDotFeatures l,
CDotFeatures r,
float64_t  width,
int32_t  size = 10 
)

constructor

Parameters
lfeatures of left-hand side
rfeatures of right-hand side
widthwidth
sizecache size

Definition at line 35 of file GaussianKernel.cpp.

~CGaussianKernel ( )
virtual

Definition at line 44 of file GaussianKernel.cpp.

Member Function Documentation

void cleanup ( )
virtual

clean up kernel

Reimplemented from CKernel.

Definition at line 49 of file GaussianKernel.cpp.

float64_t compute ( int32_t  idx_a,
int32_t  idx_b 
)
protectedvirtual

compute kernel function for features a and b idx_{a,b} denote the index of the feature vectors in the corresponding feature object

Parameters
idx_aindex a
idx_bindex b
Returns
computed kernel function at indices a,b

Reimplemented from CDotKernel.

Reimplemented in CGaussianShiftKernel.

Definition at line 81 of file GaussianKernel.cpp.

bool get_compact_enabled ( )

return value of the compact option

Returns
whether the compact option is enabled

Definition at line 125 of file GaussianKernel.h.

virtual EKernelType get_kernel_type ( )
virtual

return what type of kernel we are

Returns
kernel type GAUSSIAN

Implements CDotKernel.

Reimplemented in CGaussianShiftKernel.

Definition at line 86 of file GaussianKernel.h.

virtual const char* get_name ( ) const
virtual

return the kernel's name

Returns
name Gaussian

Reimplemented from CDotKernel.

Reimplemented in CGaussianShiftKernel.

Definition at line 92 of file GaussianKernel.h.

virtual float64_t get_width ( ) const
virtual

return the kernel's width

Returns
kernel width

Definition at line 107 of file GaussianKernel.h.

bool init ( CFeatures l,
CFeatures r 
)
virtual

initialize kernel

Parameters
lfeatures of left-hand side
rfeatures of right-hand side
Returns
if initializing was successful

free sq_{r,l}hs first

Reimplemented from CDotKernel.

Definition at line 71 of file GaussianKernel.cpp.

void load_serializable_post ( ) throw (ShogunException)
protectedvirtual

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 occurres.

Reimplemented from CKernel.

Definition at line 105 of file GaussianKernel.cpp.

void set_compact_enabled ( bool  compact)

set the compact option

Parameters
compactvalue of the compact option

Definition at line 116 of file GaussianKernel.h.

virtual void set_width ( float64_t  w)
virtual

set the kernel's width

Parameters
wkernel width

Definition at line 98 of file GaussianKernel.h.

Member Data Documentation

bool m_compact
protected

whether compact output enabled

Definition at line 175 of file GaussianKernel.h.

float64_t* sq_lhs
protected

squared left-hand side

Definition at line 171 of file GaussianKernel.h.

float64_t* sq_rhs
protected

squared right-hand side

Definition at line 173 of file GaussianKernel.h.

float64_t width
protected

width

Definition at line 169 of file GaussianKernel.h.


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

SHOGUN Machine Learning Toolbox - Documentation