root/library/bdm/stat/emix.h @ 750

/*!
  \file
  \brief Probability distributions for Mixtures of pdfs
  \author Vaclav Smidl.

  -----------------------------------
  BDM++ - C++ library for Bayesian Decision Making under Uncertainty

  Using IT++ for numerical operations
  -----------------------------------
*/

#ifndef EMIX_H
#define EMIX_H

#define LOG2  0.69314718055995

#include "../shared_ptr.h"
#include "exp_family.h"

namespace bdm {

//this comes first because it is used inside emix!

/*! \brief Class representing ratio of two densities
which arise e.g. by applying the Bayes rule.
It represents density in the form:
\f[
f(rv|rvc) = \frac{f(rv,rvc)}{f(rvc)}
\f]
where \f$ f(rvc) = \int f(rv,rvc) d\ rv \f$.

In particular this type of arise by conditioning of a mixture model.

At present the only supported operation is evallogcond().
 */
class mratio: public pdf {
protected:
        //! Nominator in the form of pdf
        const epdf* nom;

        //!Denominator in the form of epdf
        shared_ptr<epdf> den;

        //!flag for destructor
        bool destroynom;
        //!datalink between conditional and nom
        datalink_m2e dl;
public:
        //!Default constructor. By default, the given epdf is not copied!
        //! It is assumed that this function will be used only temporarily.
        mratio ( const epdf* nom0, const RV &rv, bool copy = false ) : pdf ( ), dl ( ) {
                // adjust rv and rvc

                set_rv ( rv ); // TODO co kdyby tohle samo uz nastavovalo dimension?!?!
                dim = rv._dsize();

                rvc = nom0->_rv().subt ( rv );
                dimc = rvc._dsize();

                //prepare data structures
                if ( copy ) {
                        bdm_error ( "todo" );
                        // destroynom = true;
                } else {
                        nom = nom0;
                        destroynom = false;
                }
                bdm_assert_debug ( rvc.length() > 0, "Makes no sense to use this object!" );

                // build denominator
                den = nom->marginal ( rvc );
                dl.set_connection ( rv, rvc, nom0->_rv() );
        };

        double evallogcond ( const vec &val, const vec &cond ) {
                double tmp;
                vec nom_val ( dimension() + dimc );
                dl.pushup_cond ( nom_val, val, cond );
                tmp = exp ( nom->evallog ( nom_val ) - den->evallog ( cond ) );
                return tmp;
        }
        //! Object takes ownership of nom and will destroy it
        void ownnom() {
                destroynom = true;
        }
        //! Default destructor
        ~mratio() {
                if ( destroynom ) {
                        delete nom;
                }
        }

private:
        // not implemented
        mratio ( const mratio & );
        mratio &operator= ( const mratio & );
};

/*!
* \brief Mixture of epdfs

Density function:
\f[
f(x) = \sum_{i=1}^{n} w_{i} f_i(x), \quad \sum_{i=1}^n w_i = 1.
\f]
where \f$f_i(x)\f$ is any density on random variable \f$x\f$, called \a component,

*/
class emix : public epdf {
protected:
        //! weights of the components
        vec w;

        //! Component (epdfs)
        Array<shared_ptr<epdf> > Coms;

public:
        //! Default constructor
        emix ( ) : epdf ( ) { }

        /*!
          \brief Set weights \c w and components \c Coms

          Shared pointers in Coms are kept inside this instance and
          shouldn't be modified after being passed to this method.
        */
        void set_parameters ( const vec &w, const Array<shared_ptr<epdf> > &Coms );
    
        virtual void validate ();

        vec sample() const;

        vec mean() const;

        vec variance() const;

        double evallog ( const vec &val ) const;

        vec evallog_mat ( const mat &Val ) const;

        //! Auxiliary function that returns pdflog for each component
        mat evallog_coms ( const mat &Val ) const;

        shared_ptr<epdf> marginal ( const RV &rv ) const;
        //! Update already existing marginal density  \c target
        void marginal ( const RV &rv, emix &target ) const;
        shared_ptr<pdf> condition ( const RV &rv ) const;

        //Access methods
        //! returns a pointer to the internal mean value. Use with Care!
        vec& _w() {
                return w;
        }

        //!access function
        shared_ptr<epdf> _Coms ( int i ) {
                return Coms ( i );
        }

        void set_rv ( const RV &rv ) {
                epdf::set_rv ( rv );
                for ( int i = 0; i < Coms.length(); i++ ) {
                        Coms ( i )->set_rv ( rv );
                }
        }

        //! Load from structure with elements:
        //!  \code
        //! { class='emix';
        //!   pdfs = (..., ...);     // list of pdfs in the mixture
        //!   weights = ( 0.5, 0.5 ); // weights of pdfs in the mixture
        //! }
        //! \endcode
        //!@}
        void from_setting ( const Setting &set ) {

                vec w0;
                Array<shared_ptr<epdf> > Coms0;

                UI::get ( Coms0, set, "pdfs", UI::compulsory );

                if ( !UI::get ( w0, set, "weights", UI::optional ) ) {
                        int len = Coms.length();
                        w0.set_length ( len );
                        w0 = 1.0 / len;
                }

                // TODO asi lze nacitat primocare do w a coms, jen co bude hotovy validate()
                set_parameters ( w0, Coms0 );
                validate();
        }
};
SHAREDPTR ( emix );
UIREGISTER ( emix );

/*!
* \brief Mixture of egiws

*/
class egiwmix : public egiw {
protected:
        //! weights of the components
        vec w;
        //! Component (epdfs)
        Array<egiw*> Coms;
        //!Flag if owning Coms
        bool destroyComs;
public:
        //!Default constructor
        egiwmix ( ) : egiw ( ) {};

        //! Set weights \c w and components \c Coms
        //!By default Coms are copied inside. Parameter \c copy can be set to false if Coms live externally. Use method ownComs() if Coms should be destroyed by the destructor.
        void set_parameters ( const vec &w, const Array<egiw*> &Coms, bool copy = false );

        //!return expected value
        vec mean() const;

        //!return a sample from the density
        vec sample() const;

        //!return the expected variance
        vec variance() const;

        // TODO!!! Defined to follow ANSI and/or for future development
        void mean_mat ( mat &M, mat&R ) const {};
        double evallog_nn ( const vec &val ) const {
                return 0;
        };
        double lognc () const {
                return 0;
        }

        shared_ptr<epdf> marginal ( const RV &rv ) const;
        //! marginal density update
        void marginal ( const RV &rv, emix &target ) const;

//Access methods
        //! returns a pointer to the internal mean value. Use with Care!
        vec& _w() {
                return w;
        }
        virtual ~egiwmix() {
                if ( destroyComs ) {
                        for ( int i = 0; i < Coms.length(); i++ ) {
                                delete Coms ( i );
                        }
                }
        }
        //! Auxiliary function for taking ownership of the Coms()
        void ownComs() {
                destroyComs = true;
        }

        //!access function
        egiw* _Coms ( int i ) {
                return Coms ( i );
        }

        void set_rv ( const RV &rv ) {
                egiw::set_rv ( rv );
                for ( int i = 0; i < Coms.length(); i++ ) {
                        Coms ( i )->set_rv ( rv );
                }
        }

        //! Approximation of a GiW mix by a single GiW pdf
        egiw* approx();
};

/*! \brief Chain rule decomposition of epdf

Probability density in the form of Chain-rule decomposition:
\[
f(x_1,x_2,x_3) = f(x_1|x_2,x_3)f(x_2,x_3)f(x_3)
\]
Note that
*/
class mprod: public pdf {
private:
        Array<shared_ptr<pdf> > pdfs;

        //! Data link for each pdfs
        Array<shared_ptr<datalink_m2m> > dls;

protected:
        //! dummy epdf used only as storage for RV and dim
        epdf iepdf;

public:
        //! \brief Default constructor
        mprod() { }

        /*!\brief Constructor from list of mFacs
        */
        mprod ( const Array<shared_ptr<pdf> > &mFacs ) {
                set_elements ( mFacs );
        }
        //! Set internal \c pdfs from given values
        void set_elements ( const Array<shared_ptr<pdf> > &mFacs );

        double evallogcond ( const vec &val, const vec &cond );

        vec evallogcond_mat ( const mat &Dt, const vec &cond );

        vec evallogcond_mat ( const Array<vec> &Dt, const vec &cond );

        //TODO smarter...
        vec samplecond ( const vec &cond ) {
                //! Ugly hack to help to discover if mpfs are not in proper order. Correct solution = check that explicitely.
                vec smp = std::numeric_limits<double>::infinity() * ones ( dimension() );
                vec smpi;
                // Hard assumption here!!! We are going backwards, to assure that samples that are needed from smp are already generated!
                for ( int i = ( pdfs.length() - 1 ); i >= 0; i-- ) {
                        // generate contribution of this pdf
                        smpi = pdfs ( i )->samplecond ( dls ( i )->get_cond ( smp , cond ) );
                        // copy contribution of this pdf into smp
                        dls ( i )->pushup ( smp, smpi );
                }
                return smp;
        }

        //! Load from structure with elements:
        //!  \code
        //! { class='mprod';
        //!   pdfs = (..., ...);     // list of pdfs in the order of chain rule
        //! }
        //! \endcode
        //!@}
        void from_setting ( const Setting &set ) {
                Array<shared_ptr<pdf> > atmp; //temporary Array
                UI::get ( atmp, set, "pdfs", UI::compulsory );
                set_elements ( atmp );
        }
};
UIREGISTER ( mprod );
SHAREDPTR ( mprod );

//! Product of independent epdfs. For dependent pdfs, use mprod.
class eprod: public epdf {
protected:
        //! Components (epdfs)
        Array<const epdf*> epdfs;
        //! Array of indeces
        Array<datalink*> dls;
public:
        //! Default constructor
        eprod () : epdfs ( 0 ), dls ( 0 ) {};
        //! Set internal
        void set_parameters ( const Array<const epdf*> &epdfs0, bool named = true ) {
                epdfs = epdfs0;//.set_length ( epdfs0.length() );
                dls.set_length ( epdfs.length() );

                bool independent = true;
                if ( named ) {
                        for ( int i = 0; i < epdfs.length(); i++ ) {
                                independent = rv.add ( epdfs ( i )->_rv() );
                                bdm_assert_debug ( independent, "eprod:: given components are not independent." );
                        }
                        dim = rv._dsize();
                } else {
                        dim = 0;
                        for ( int i = 0; i < epdfs.length(); i++ ) {
                                dim += epdfs ( i )->dimension();
                        }
                }
                //
                int cumdim = 0;
                int dimi = 0;
                int i;
                for ( i = 0; i < epdfs.length(); i++ ) {
                        dls ( i ) = new datalink;
                        if ( named ) {
                                dls ( i )->set_connection ( epdfs ( i )->_rv() , rv );
                        } else {
                                dimi = epdfs ( i )->dimension();
                                dls ( i )->set_connection ( dimi, dim, linspace ( cumdim, cumdim + dimi - 1 ) );
                                cumdim += dimi;
                        }
                }
        }

        vec mean() const;

        vec variance() const;

        vec sample() const;

        double evallog ( const vec &val ) const;

        //!access function
        const epdf* operator () ( int i ) const {
                bdm_assert_debug ( i < epdfs.length(), "wrong index" );
                return epdfs ( i );
        }

        //!Destructor
        ~eprod() {
                for ( int i = 0; i < epdfs.length(); i++ ) {
                        delete dls ( i );
                }
        }
};


/*! \brief Mixture of pdfs with constant weights, all pdfs are of equal RV and RVC

*/
class mmix : public pdf {
protected:
        //! Component (pdfs)
        Array<shared_ptr<pdf> > Coms;
        //!weights of the components
        vec w;
public:
        //!Default constructor
        mmix() : Coms ( 0 ) { }

        //! Set weights \c w and components \c R
        void set_parameters ( const vec &w0, const Array<shared_ptr<pdf> > &Coms0 ) {
                //!\todo check if all components are OK
                Coms = Coms0;
                w = w0;

                if ( Coms0.length() > 0 ) {
                        set_rv ( Coms ( 0 )->_rv() );
                        dim = rv._dsize();
                        set_rvc ( Coms ( 0 )->_rvc() );
                        dimc = rvc._dsize();
                }
        }
        double evallogcond ( const vec &dt, const vec &cond ) {
                double ll = 0.0;
                for ( int i = 0; i < Coms.length(); i++ ) {
                        ll += Coms ( i )->evallogcond ( dt, cond );
                }
                return ll;
        }

        vec samplecond ( const vec &cond );

        //! Load from structure with elements:
        //!  \code
        //! { class='mmix';
        //!   pdfs = (..., ...);     // list of pdfs in the mixture
        //!   weights = ( 0.5, 0.5 ); // weights of pdfs in the mixture
        //! }
        //! \endcode
        //!@}
        void from_setting ( const Setting &set ) {
                UI::get ( Coms, set, "pdfs", UI::compulsory );

                // TODO ma byt zde, ci ve validate()?
                if ( Coms.length() > 0 ) {
                        set_rv ( Coms ( 0 )->_rv() );
                        dim = rv._dsize();
                        set_rvc ( Coms ( 0 )->_rvc() );
                        dimc = rvc._dsize();
                }

                if ( !UI::get ( w, set, "weights", UI::optional ) ) {
                        int len = Coms.length();
                        w.set_length ( len );
                        w = 1.0 / len;
                }
        }
};
SHAREDPTR ( mmix );
UIREGISTER ( mmix );

}
#endif //MX_H