seq_step_ensemble.hpp

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#ifndef FSTSEARCHSEQSTEPENSEMBLE_H
#define FSTSEARCHSEQSTEPENSEMBLE_H
 /* 
=========================================================================
Copyright and license:
  * FST4 software (with the exception of any bundled or externally linked
    third-party components) is Copyright (C) 2000-present Institute of
    Information Theory and Automation of the Czech Academy of Sciences (UTIA).
  * FST4 is free software: you can redistribute it and/or modify it under
    the terms of the GNU Affero General Public License as published by the
    Free Software Foundation, version 3. The full text of the license is in
    the file LICENSE in the distribution root and at
    https://www.gnu.org/licenses/agpl-3.0.html.
  * FST4 is distributed in the hope that it will be useful, but WITHOUT ANY
    WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public
    License for more details.
  * Closed-source use without the AGPL's copyleft obligations requires a
    commercial license from UTIA; in case of interest write to
    utia@utia.cas.cz. LICENSING.md in the distribution root explains both
    options, the contributor license agreement that every contribution
    requires, and the contacts (technical questions and pull requests:
    somol@utia.cas.cz, with "FST" in the subject line).
========================================================================== */
 
#include <memory>
#include <cassert>
#include <iostream>
#include <sstream>
#include <list>
#include <vector>
#include <map>
#include "error.hpp"
#include "global.hpp"
#include "seq_step.hpp"
#include "criterion.hpp"
#include "candidate_evaluator.hpp"
#include "candidate_evaluator_sequential.hpp"
 
/*============== Template parameter type naming conventions ==============
--------- Numeric types: -------------------------------------------------
DATATYPE - data sample values - usually real numbers (but may be integers
          in text processing etc.)
REALTYPE - must be real numbers - for representing intermediate results of 
          calculations like mean, covariance etc.
IDXTYPE - index values for enumeration of data samples - (nonnegative) integers, 
          extent depends on numbers of samples in data
DIMTYPE - index values for enumeration of features (dimensions), or classes (not 
          class sizes) - (nonnegative) integers, usually lower extent than IDXTYPE, 
          but be aware of expressions like _classes*_features*_features ! 
          in linearized representations of feature matrices for all classes
BINTYPE - feature selection marker type - represents ca. <10 different feature 
          states (selected, deselected, sel./desel. temporarily 1st nested loop, 2nd...)
RETURNTYPE - criterion value: real value, but may be extended in future to support 
          multiple values 
--------- Class types: ---------------------------------------------------
SUBSET       - class of class type Subset 
CLASSIFIER   - class implementing interface defined in abstract class Classifier 
EVALUATOR    - class implementing interface defined in abstract class Sequential_Step 
DISTANCE     - class implementing interface defined in abstract class Distance 
DATAACCESSOR - class implementing interface defined in abstract class Data_Accessor 
INTERVALCONTAINER - class of class type Data_Intervaller 
CONTAINER    - STL container of class type Data_Interval  
========================================================================== */
 
namespace FST {
 
//----------------------------------------------------------------------------

template<class RETURNTYPE, typename DIMTYPE, class SUBSET, class CRITERION>
class Sequential_Step_Ensemble : public Sequential_Step<RETURNTYPE,DIMTYPE,SUBSET,CRITERION>{
public:
        typedef Sequential_Step<RETURNTYPE,DIMTYPE,SUBSET,CRITERION> parent; 
        typedef std::shared_ptr<CRITERION> PCriterion;             
        typedef std::shared_ptr<Criterion<RETURNTYPE,SUBSET> > PAbstractCriterion; 
        typedef std::vector<PAbstractCriterion> PAbstractCriteria; 
        typedef std::shared_ptr<PAbstractCriteria> PEnsembleCriteria; 
        typedef std::shared_ptr<SUBSET> PSubset;                  
        typedef Candidate_Evaluator<RETURNTYPE,DIMTYPE,SUBSET,Criterion<RETURNTYPE,SUBSET> > EVALUATORENGINE; 
        typedef std::shared_ptr<EVALUATORENGINE> PEvaluatorEngine; 
        Sequential_Step_Ensemble(const PEnsembleCriteria ensemble, PEvaluatorEngine engine=PEvaluatorEngine()):Sequential_Step<RETURNTYPE,DIMTYPE,SUBSET,CRITERION>(),_engine(engine),track(false) {assert(ensemble); _ensemble=ensemble; if(!_engine) _engine.reset(new Candidate_Evaluator_Sequential<RETURNTYPE,DIMTYPE,SUBSET,Criterion<RETURNTYPE,SUBSET> >()); notify("Sequential_Step_Ensemble constructor.");}
        virtual ~Sequential_Step_Ensemble() {notify("Sequential_Step_Ensemble destructor.");}
 
        // NOTE: crit (as well as all criteria in ensemble) is expected to be already initialize()d before use here
        inline bool evaluate_candidates(RETURNTYPE &result, const PSubset sub, const PCriterion crit, const DIMTYPE _generalization_level=1, std::ostream& os=std::cout) override; 

        virtual std::ostream& print(std::ostream& os) const override {
                if(_engine->is_threaded()) os << "Sequential_Step_Ensemble(threads="<<_engine->get_max_threads()<<")";
                else os << "Sequential_Step_Ensemble()";
                if(parent::result_tracker_active()) os << " with " << *parent::_tracker;
                return os;
        }
protected:
        inline bool order_candidates(const PSubset sub);
 
        PEvaluatorEngine _engine; 
        PEnsembleCriteria _ensemble; 
        
        class SubsetCandidate {
        public:
                SubsetCandidate(const RETURNTYPE value, const PSubset sub, const DIMTYPE tfeature) : _value(value), _sub(new SUBSET(*sub)), _tempfeature(tfeature) {}
                SubsetCandidate(const SubsetCandidate& fc) : _value(fc._value), _sub(fc._sub), _tempfeature(fc._tempfeature) {}
                RETURNTYPE _value;
                const PSubset _sub;         
                const DIMTYPE _tempfeature; 
        };
        typedef std::shared_ptr<SubsetCandidate> PSubsetCandidate; 
        typedef std::list<SubsetCandidate> CANDIDATELIST;          
        typedef std::shared_ptr<CANDIDATELIST> PCANDIDATELIST;     
        typedef std::vector<PCANDIDATELIST> CANDIDATELISTS;        
        CANDIDATELISTS _lists; 
        typedef std::map<DIMTYPE, PSubsetCandidate> FINALVALUES;   
        FINALVALUES _final; 
 
        typename CANDIDATELISTS::iterator oiter; 
        typename CANDIDATELIST::iterator iter;   
        typename FINALVALUES::iterator fiter;    
 
private:
        std::unique_ptr<SUBSET> tmp_step_sub; 
        bool track; 
};
 
 
template<class RETURNTYPE, typename DIMTYPE, class SUBSET, class CRITERION>
bool Sequential_Step_Ensemble<RETURNTYPE,DIMTYPE,SUBSET,CRITERION>::order_candidates(const PSubset sub)
{
        assert(sub);
        assert(_engine);
        assert(_ensemble);
        assert(!_ensemble->empty());
        assert(_ensemble->size()==_lists.size());
 
        _final.clear();
 
        // first pass (master, no criterion evaluation): register each candidate's temporary
        // feature in _final and count the candidates (the threaded engine sizes its result
        // storage from the count)
        DIMTYPE _tfeat;
        DIMTYPE _candidates=0;
        bool b=sub->getFirstCandidateSubset(1,false/*reverse*/); if(!b) return false; // no candidate subsets can be traversed for whatever reason
        while(b) {
                if(!sub->getFirstTemporaryFeature(_tfeat)) return false; // just one exists due to the getFirstCandidateSubset(1,false/*reverse*/) call above
                assert(_tfeat<sub->get_n());
                PSubsetCandidate _cs(new SubsetCandidate(0.0,sub,_tfeat));
                _final.insert( make_pair(_tfeat,_cs));
                ++_candidates;
                b=sub->getNextCandidateSubset();
        }
        if(_candidates==0) return false;
 
        // per-member engine batches: candidates are re-enumerated for each ensemble member and
        // evaluated through the injected engine; the per-result callback (fired on the master in
        // candidate order) does the sorted insertion into the member's ordered list, so the
        // resulting lists are the same for any thread count. The candidate's temporary feature
        // rides along as the engine's feature tag.
        for(typename PAbstractCriteria::size_type j=0;j<_ensemble->size();j++)
        {
                PCANDIDATELIST lst=_lists[j];
                typename EVALUATORENGINE::ResultCallback on_result=[lst](const RETURNTYPE val, const PSubset &csub, const DIMTYPE tfeat) {
                        typename CANDIDATELIST::iterator it;
                        for(it=lst->begin(); it!=lst->end() && val<it->_value; it++);
                        lst->insert(it,SubsetCandidate(val,csub,tfeat));
                };
                _engine->initialize((*_ensemble)[j],_candidates,on_result);
                b=sub->getFirstCandidateSubset(1,false/*reverse*/); if(!b) return false;
                while(b) {
                        if(!sub->getFirstTemporaryFeature(_tfeat)) return false;
                        if(!_engine->add_candidate(sub,_tfeat)) return false;
                        b=sub->getNextCandidateSubset();
                }
                if(!_engine->collect()) return false;
        }
        return true;
}
 
template<class RETURNTYPE, typename DIMTYPE, class SUBSET, class CRITERION>
bool Sequential_Step_Ensemble<RETURNTYPE,DIMTYPE,SUBSET,CRITERION>::evaluate_candidates(RETURNTYPE &result, const PSubset sub, const PCriterion crit, const DIMTYPE _generalization_level, std::ostream& os)
{
        assert(sub);
        assert(sub->get_n()>0);
        assert(crit);
        assert(_ensemble);
        assert(!_ensemble->empty());
        if(_generalization_level!=1) throw FST::fst_error("Sequential_Step_Ensemble currently does not support generalization level other than 1.");
        track=parent::result_tracker_active();
        
        _lists.reserve(_ensemble->size());
        while(_lists.size()<_ensemble->size()) _lists.push_back(PCANDIDATELIST(new CANDIDATELIST));
        assert(_lists.size()==_ensemble->size());
        for(oiter=_lists.begin(); oiter!=_lists.end(); oiter++) (*oiter)->clear();
 
        if(!order_candidates(sub)) {if(parent::output_normal()) {std::ostringstream sos; sos << "FAILURE order_candidates() sub=" << *sub << std::endl << std::endl << std::flush; syncout::print(os,sos);} return false;}
 
        assert(_final.size()>0);
        for(fiter=_final.begin();fiter!=_final.end();fiter++) (*fiter).second->_value=0.0;
 
        // Collect ordering votes: walk each member's best-first list and add the candidate's
        // RANK (1 = the member's most preferred) to that feature's tally in _final. Ranking is
        // DENSE and ties-aware - the rank advances only when the criterion value actually drops,
        // so candidates a member scored equally receive the same rank and the next distinct
        // value gets rank+1 (not rank+number-of-tied). A feature's tally therefore lies between
        // (number of members) for a unanimous first choice and (number of members)*(number of
        // distinct values) at worst, and LOWER is better.
        RETURNTYPE _lastval;
        DIMTYPE _curposition;
        for(oiter=_lists.begin(); oiter!=_lists.end(); oiter++)
        {
                iter=(*oiter)->begin();
                _curposition=1;
                _lastval=iter->_value;
                _final[iter->_tempfeature]->_value+=_curposition;
                iter++;
                while(iter!=(*oiter)->end())
                {
                        if(iter->_value<_lastval) {_curposition++; _lastval=iter->_value;}
                        _final[iter->_tempfeature]->_value+=_curposition;
                        iter++;
                }
        }
        
        if(!tmp_step_sub || tmp_step_sub->get_n()<sub->get_n()) tmp_step_sub.reset(new SUBSET(sub->get_n()));
        
        // Pick the candidate with the LOWEST vote tally. _lastval doubles as the
        // "nothing picked yet" sentinel: a real tally is at least 1 per ensemble member, so the
        // initial 0.0 (tested as <1.0) makes the first entry of _final the provisional winner,
        // after which only a strictly smaller positive tally displaces it. _final is a map keyed
        // by feature index, so when several features tie on the tally the LOWEST feature index
        // wins - the step is deterministic.
        _lastval=0.0;
        _curposition=0;
        for(fiter=_final.begin();fiter!=_final.end();fiter++) 
        {
                if(_lastval<1.0 || ( (*fiter).second->_value < _lastval && (*fiter).second->_value > 0.0 ))
                {
                        _lastval=(*fiter).second->_value; 
                        _curposition=(*fiter).second->_tempfeature;
                        tmp_step_sub->stateless_copy(*((*fiter).second->_sub)); // keep the best candidate's subset
                }
        }
        sub->stateless_copy(*tmp_step_sub);
        assert(sub->get_d()!=0);
        
        if(!crit->evaluate(result,sub)) {if(parent::output_normal()) {std::ostringstream sos; sos << "FAILURE crit->eval() sub=" << *(sub) << std::endl << std::endl << std::flush; syncout::print(os,sos);} return false;}
        if(track) parent::_tracker->add(result,sub);
 
        if(parent::output_detailed()) {
                std::ostringstream sos; 
                sos << "---------------- "<< std::endl;
                sos << "candidate lists: "<< std::endl;
                int lst=0;
                for(oiter=_lists.begin(); oiter!=_lists.end(); oiter++)
                {
                        sos << lst++ << ": ";
                        for(iter=(*oiter)->begin();iter!=(*oiter)->end();iter++) sos << iter->_tempfeature << "," <<iter->_value << " | ";
                        sos << std::endl;
                }
                sos << "final list: "<<std::endl;
                sos << "   ";
                assert(_final.size()>0);
        
                for(fiter=_final.begin();fiter!=_final.end();fiter++) sos << (*fiter).first << ") " << (*fiter).second->_value << " | ";
                sos << std::endl;
                sos << "verified crit value=" << result << std::endl;
                sos << std::endl << std::flush; 
                syncout::print(os,sos);
        }
        
        return true;
}
 
 
} // namespace
#endif // FSTSEARCHSEQSTEPENSEMBLE_H ///:~