SHOGUN
4.2.0
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Preprocessor PCA performs principial component analysis on input feature vectors/matrices. When the init method in PCA is called with proper feature matrix X (with say N number of vectors and D feature dimension), a transformation matrix is computed and stored internally. This transformation matrix is then used to transform all D-dimensional feature vectors or feature matrices (with D feature dimensions) supplied via apply_to_feature_matrix or apply_to_feature_vector methods. This tranformation outputs the T-Dimensional approximation of all these input vectors and matrices (where T<=min(D,N)). The transformation matrix is essentially a DxT matrix, the columns of which correspond to the eigenvectors of the covariance matrix(XX') having top T eigenvalues.
This class provides 3 method options to compute the transformation matrix : EVD : Eigen Value Decomposition of Covariance Matrix ( \(XX^T\)) The covariance matrix \(XX^T\) is first formed internally and then its eigenvectors and eigenvalues are computed. The time complexity of this method is \(~10D^3\) and should be used when N > D.
SVD : Singular Value Decomposition of feature matrix X The transpose of feature matrix, \(X^T\), is decomposed using SVD. \(X^T = UDV^T\) The matrix V in this decomposition contains the required eigenvectors and the diagonal entries of the diagonal matrix D correspond to the non-negative eigenvalues. Eigenvalue, \(e_i\), is derived from a diagonal element, \(d_i\), using the formula \(e_i = \frac{\sqrt{d_i}}{N-1}\). The time complexity of this method is \(~14DN^2\) and should be used when N < D.
AUTO : This mode automagically chooses one of the above modes for the user based on whether N > D (chooses EVD) or N < D (chooses SVD).
This class provides 3 modes to determine the value of T :
FIXED_NUMBER : T is supplied by user directly using set_target_dims method
VARIANCE_EXPLAINED : The user supplies the fractional variance that he wants preserved in the target dimension T. From this supplied fractional variance (thresh), T is calculated as the smallest k such that the ratio of sum of largest k eigenvalues over total sum of all eigenvalues is greater than thresh.
THRESH : The user supplies a threshold. All eigenvectors with corresponding eigenvalue greater than the supplied threshold are chosen.
An option for whitening the transformation matrix is also given - do_whitening. Setting this option normalizes the eigenvectors (ie. the columns of transformation matrix) by dividing them with the square root of corresponding eigenvalues.
Note that vectors/matrices don't have to have zero mean as it is substracted within the class.
Public Member Functions | |
CPCA (bool do_whitening=false, EPCAMode mode=FIXED_NUMBER, float64_t thresh=1e-6, EPCAMethod method=AUTO, EPCAMemoryMode mem_mode=MEM_REALLOCATE) | |
CPCA (EPCAMethod method, bool do_whitening=false, EPCAMemoryMode mem=MEM_REALLOCATE) | |
virtual | ~CPCA () |
virtual bool | init (CFeatures *features) |
virtual void | cleanup () |
virtual SGMatrix< float64_t > | apply_to_feature_matrix (CFeatures *features) |
virtual SGVector< float64_t > | apply_to_feature_vector (SGVector< float64_t > vector) |
SGMatrix< float64_t > | get_transformation_matrix () |
SGVector< float64_t > | get_eigenvalues () |
SGVector< float64_t > | get_mean () |
virtual const char * | get_name () const |
virtual EPreprocessorType | get_type () const |
EPCAMemoryMode | get_memory_mode () const |
void | set_memory_mode (EPCAMemoryMode e) |
void | set_eigenvalue_zero_tolerance (float64_t eigenvalue_zero_tolerance=1e-15) |
float64_t | get_eigenvalue_zero_tolerance () const |
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 CFeatures * | apply (CFeatures *features) |
virtual EFeatureClass | get_feature_class () |
return that we are dense features (just fixed size matrices) More... | |
virtual EFeatureType | get_feature_type () |
return feature type More... | |
virtual CSGObject * | shallow_copy () const |
virtual CSGObject * | deep_copy () const |
virtual bool | is_generic (EPrimitiveType *generic) const |
template<class T > | |
void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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void | set_generic () |
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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 | |
void | init () |
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 | |
SGMatrix< float64_t > | m_transformation_matrix |
int32_t | num_dim |
int32_t | num_old_dim |
SGVector< float64_t > | m_mean_vector |
SGVector< float64_t > | m_eigenvalues_vector |
bool | m_initialized |
bool | m_whitening |
EPCAMode | m_mode |
float64_t | m_thresh |
EPCAMemoryMode | m_mem_mode |
EPCAMethod | m_method |
float64_t | m_eigenvalue_zero_tolerance |
int32_t | m_target_dim |
CDistance * | m_distance |
CKernel * | m_kernel |
CEmbeddingConverter * | m_converter |
CPCA | ( | bool | do_whitening = false , |
EPCAMode | mode = FIXED_NUMBER , |
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float64_t | thresh = 1e-6 , |
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EPCAMethod | method = AUTO , |
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EPCAMemoryMode | mem_mode = MEM_REALLOCATE |
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standard constructor
do_whitening | normalize columns(eigenvectors) in transformation matrix |
mode | mode of pca : FIXED_NUMBER/VARIANCE_EXPLAINED/THRESHOLD |
thresh | threshold value for VARIANCE_EXPLAINED or THRESHOLD mode |
method | Matrix decomposition method used : SVD/EVD/AUTO[default] |
mem_mode | memory usage mode of PCA : MEM_REALLOCATE/MEM_IN_PLACE |
CPCA | ( | EPCAMethod | method, |
bool | do_whitening = false , |
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EPCAMemoryMode | mem = MEM_REALLOCATE |
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generic interface for applying the preprocessor. used as a wrapper for apply_to_feature_matrix() method
features | the dense input features |
Implements CPreprocessor.
apply preprocessor to feature matrix
features | features |
Reimplemented from CDimensionReductionPreprocessor.
apply preprocessor to feature vector
vector | feature vector |
Reimplemented from CDimensionReductionPreprocessor.
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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.
dict | dictionary of parameters to be built. |
Definition at line 630 of file SGObject.cpp.
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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.
Definition at line 747 of file SGObject.cpp.
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A deep copy. All the instance variables will also be copied.
Definition at line 231 of file SGObject.cpp.
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.
other | object to compare with |
accuracy | accuracy to use for comparison (optional) |
tolerant | allows linient check on float equality (within accuracy) |
Definition at line 651 of file SGObject.cpp.
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Getter for a class parameter, identified by a Tag. Throws an exception if the class does not have such a parameter.
_tag | name and type information of parameter |
Definition at line 367 of file SGObject.h.
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Getter for a class parameter, identified by a name. Throws an exception if the class does not have such a parameter.
name | name of the parameter |
Definition at line 388 of file SGObject.h.
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getter for distance
Definition at line 88 of file DimensionReductionPreprocessor.cpp.
float64_t get_eigenvalue_zero_tolerance | ( | ) | const |
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return that we are dense features (just fixed size matrices)
Implements CPreprocessor.
Reimplemented in CRandomFourierGaussPreproc.
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EPCAMemoryMode get_memory_mode | ( | ) | const |
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Definition at line 531 of file SGObject.cpp.
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Returns description of a given parameter string, if it exists. SG_ERROR otherwise
param_name | name of the parameter |
Definition at line 555 of file SGObject.cpp.
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Returns index of model selection parameter with provided index
param_name | name of model selection parameter |
Definition at line 568 of file SGObject.cpp.
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Reimplemented from CDimensionReductionPreprocessor.
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getter for target dimension
Definition at line 76 of file DimensionReductionPreprocessor.cpp.
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Reimplemented from CDimensionReductionPreprocessor.
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Checks if object has a class parameter identified by a name.
name | name of the parameter |
Definition at line 289 of file SGObject.h.
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Checks if object has a class parameter identified by a Tag.
tag | tag of the parameter containing name and type information |
Definition at line 301 of file SGObject.h.
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Checks if a type exists for a class parameter identified by a name.
name | name of the parameter |
Definition at line 312 of file SGObject.h.
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initialize preprocessor from features
features |
Reimplemented from CDimensionReductionPreprocessor.
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If the SGSerializable is a class template then TRUE will be returned and GENERIC is set to the type of the generic.
generic | set to the type of the generic if returning TRUE |
Definition at line 329 of file SGObject.cpp.
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Load this object from file. If it will fail (returning FALSE) then this object will contain inconsistent data and should not be used!
file | where to load from |
prefix | prefix for members |
Definition at line 402 of file SGObject.cpp.
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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.
ShogunException | will 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.
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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.
ShogunException | will 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.
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Definition at line 295 of file SGObject.cpp.
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prints all parameter registered for model selection and their type
Definition at line 507 of file SGObject.cpp.
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prints registered parameters out
prefix | prefix for members |
Definition at line 341 of file SGObject.cpp.
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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.
_tag | name and type information of parameter |
value | value of the parameter |
Definition at line 439 of file SGObject.h.
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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.
name | name of the parameter |
value | value of the parameter along with type information |
Definition at line 452 of file SGObject.h.
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virtualinherited |
Save this object to file.
file | where to save the object; will be closed during returning if PREFIX is an empty string. |
prefix | prefix for members |
Definition at line 347 of file SGObject.cpp.
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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.
ShogunException | will be thrown if an error occurs. |
Reimplemented in CKernel.
Definition at line 469 of file SGObject.cpp.
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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.
ShogunException | will 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.
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Setter for a class parameter, identified by a Tag. Throws an exception if the class does not have such a parameter.
_tag | name and type information of parameter |
value | value of the parameter |
Definition at line 328 of file SGObject.h.
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Setter for a class parameter, identified by a name. Throws an exception if the class does not have such a parameter.
name | name of the parameter |
value | value of the parameter along with type information |
Definition at line 354 of file SGObject.h.
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setter for distance
distance | distance to set |
Definition at line 81 of file DimensionReductionPreprocessor.cpp.
void set_eigenvalue_zero_tolerance | ( | float64_t | eigenvalue_zero_tolerance = 1e-15 | ) |
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Definition at line 74 of file SGObject.cpp.
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Definition at line 79 of file SGObject.cpp.
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Definition at line 84 of file SGObject.cpp.
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Definition at line 89 of file SGObject.cpp.
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Definition at line 94 of file SGObject.cpp.
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Definition at line 99 of file SGObject.cpp.
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Definition at line 104 of file SGObject.cpp.
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Definition at line 109 of file SGObject.cpp.
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Definition at line 114 of file SGObject.cpp.
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Definition at line 119 of file SGObject.cpp.
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Definition at line 124 of file SGObject.cpp.
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Definition at line 129 of file SGObject.cpp.
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Definition at line 134 of file SGObject.cpp.
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Definition at line 139 of file SGObject.cpp.
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Definition at line 144 of file SGObject.cpp.
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set generic type to T
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set the parallel object
parallel | parallel object to use |
Definition at line 274 of file SGObject.cpp.
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set the version object
version | version object to use |
Definition at line 316 of file SGObject.cpp.
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setter for kernel
kernel | kernel to set |
Definition at line 94 of file DimensionReductionPreprocessor.cpp.
void set_memory_mode | ( | EPCAMemoryMode | e | ) |
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setter for target dimension
dim | target dimension |
Definition at line 70 of file DimensionReductionPreprocessor.cpp.
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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.
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unset generic type
this has to be called in classes specializing a template class
Definition at line 336 of file SGObject.cpp.
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Updates the hash of current parameter combination
Definition at line 281 of file SGObject.cpp.
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io
Definition at line 537 of file SGObject.h.
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protectedinherited |
embedding converter to be used
Definition at line 127 of file DimensionReductionPreprocessor.h.
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distance to be used
Definition at line 121 of file DimensionReductionPreprocessor.h.
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parameters wrt which we can compute gradients
Definition at line 552 of file SGObject.h.
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Hash of parameter values
Definition at line 555 of file SGObject.h.
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kernel to be used
Definition at line 124 of file DimensionReductionPreprocessor.h.
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model selection parameters
Definition at line 549 of file SGObject.h.
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parameters
Definition at line 546 of file SGObject.h.
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target dim of dimensionality reduction preprocessor
Definition at line 118 of file DimensionReductionPreprocessor.h.
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parallel
Definition at line 540 of file SGObject.h.
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version
Definition at line 543 of file SGObject.h.