FST::Criterion_Subset_Size< RETURNTYPE, SUBSET > Class Template Reference

Returns the (positive) subset size sub->get_d() - since FST4 searches maximize, this rates LARGER subsets higher. Wrap in Criterion_Negative to favor smaller subsets instead. More...

#include <criterion_subsetsize.hpp>

Inheritance diagram for FST::Criterion_Subset_Size< RETURNTYPE, SUBSET >:

Public Types
typedef Clonable_Impl< Criterion_Subset_Size, Criterion< RETURNTYPE, SUBSET > >	parent_impl
	implements clone(); sharing/stateless_clone throw in Criterion
typedef std::shared_ptr< SUBSET >	PSubset
	shared pointer to the feature subset being evaluated
Public Types inherited from FST::Criterion< RETURNTYPE, SUBSET >
typedef std::shared_ptr< SUBSET >	PSubset
	shared pointer to the feature subset being evaluated

Public Member Functions
virtual bool	evaluate (RETURNTYPE &result, const PSubset sub) override
	Scores the given feature subset; higher is better (FST4 searches maximize).
virtual std::ostream &	print (std::ostream &os) const override
	writes a human-readable identification of the object; base default writes nothing
Public Member Functions inherited from FST::Clonable_Impl< Criterion_Subset_Size< RETURNTYPE, SUBSET >, Criterion< RETURNTYPE, SUBSET > >
Criterion< RETURNTYPE, SUBSET > *	clone () const override
	dispatches to the DEEP_KIND mechanism (default CLONE_DEEP: Derived's copy-constructor)
Criterion< RETURNTYPE, SUBSET > *	sharing_clone () const override
	dispatches to the SHARING_KIND mechanism (default CLONE_INHERIT: defers to Base, which throws by family convention)
Criterion< RETURNTYPE, SUBSET > *	stateless_clone () const override
	dispatches to the STATELESS_KIND mechanism (default CLONE_INHERIT: defers to Base, which throws by family convention)
Public Member Functions inherited from FST::Criterion< RETURNTYPE, SUBSET >
virtual bool	is_monotonic () const
Criterion *	sharing_clone () const override
Criterion *	stateless_clone () const override
Public Member Functions inherited from FST::Clonable
bool	is_clone () const
bool	is_sharing () const
	true if this instance is a sharing_clone() result (referencing, not owning, the source's structures)
bool	is_sharing_clone () const
	true if this instance is BOTH a clone and sharing – i.e. specifically a sharing_clone() result, not a clone()/stateless_clone() one

Private Member Functions
	Criterion_Subset_Size (const Criterion_Subset_Size &css)
	Copy-constructor; the class carries no state of its own beyond what parent_impl copies.

Private Attributes
friend	parent_impl

Additional Inherited Members
Protected Member Functions inherited from FST::Clonable
void	set_cloned (const bool cloned=true)
	marks/unmarks this instance as a clone; call from clone()/stateless_clone() overrides (Clonable_Impl does this automatically)
void	set_sharing (const bool sharing=true)
	marks/unmarks this instance as sharing (see is_sharing())
void	set_sharing_cloned (const bool cloned=true, const bool sharing=true)
	sets both flags at once; call from sharing_clone() overrides (Clonable_Impl does this automatically)

Detailed Description

template<class RETURNTYPE, class SUBSET>
class FST::Criterion_Subset_Size< RETURNTYPE, SUBSET >

Returns the (positive) subset size sub->get_d() - since FST4 searches maximize, this rates LARGER subsets higher. Wrap in Criterion_Negative to favor smaller subsets instead.

This trivial criterion is intended as secondary criterion only to be used in conjunction with Result_Tracker_Regularizer, implementing feature selection regularization (improvement of feature selection generalization ability and result robustness) as described in paper "Somol, Grim, Pudil: The Problem of Fragile Feature Subset Preference in Feature Selection Methods and A Proposal of Algorithmic Workaround. In Proc. ICPR 2010. IEEE Computer Society, 2010". In the fst4 command-line tool this is what --regularize-by subsetsize selects, together with --regularize-margins and --tracker regularizer.

Note

Unlike the model-based criteria, which score the raw marker set they are handed and therefore read Subset::get_d_raw(), this one reads Subset::get_d(): the count of currently selected features EXCLUDING frozen ones, independent of the forward/backward search mode. That is the subset size the search itself manipulates, which is the quantity the regularization trade-off is about.

Examples

demo52t.cpp.

Member Function Documentation

evaluate()

template<class RETURNTYPE, class SUBSET>

virtual bool FST::Criterion_Subset_Size< RETURNTYPE, SUBSET >::evaluate ( RETURNTYPE & result, const PSubset sub )

inlineoverridevirtual

Scores the given feature subset; higher is better (FST4 searches maximize).

Parameters

result	set to the criterion value on success; left unspecified on failure
sub	the (fixed) subset to evaluate – only its selected features are read

Returns

false if the subset cannot be evaluated at all (e.g. too small for the model, or singular statistics). This is NOT a per-candidate reject: callers treat it as fatal for the current search step or run – the sequential-step candidate evaluator marks its whole batch failed, streaming searches abort, and Branch & Bound throws. A criterion that can legitimately be undefined on some subsets must guard against reaching those subsets another way (e.g. a minimum-subset-size constraint), not by relying on evaluate() to skip them.

Implements FST::Criterion< RETURNTYPE, SUBSET >.

print()

template<class RETURNTYPE, class SUBSET>

virtual std::ostream & FST::Criterion_Subset_Size< RETURNTYPE, SUBSET >::print ( std::ostream & os ) const

inlineoverridevirtual

writes a human-readable identification of the object; base default writes nothing

Reimplemented from FST::Clonable.

Member Data Documentation

parent_impl

template<class RETURNTYPE, class SUBSET>

friend FST::Criterion_Subset_Size< RETURNTYPE, SUBSET >::parent_impl

private

grants Clonable_Impl access to the copy-constructor

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

• /Users/psms/dev/devtest1/_src_criteria/criterion_subsetsize.hpp