ProductKernel.h

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/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * Copyright (C) 2012 Jacob Walker
 * 
 * Code adapted from CCombinedKernel
 */

#ifndef _PRODUCTKERNEL_H___
#define _PRODUCTKERNEL_H___

#include <shogun/lib/List.h>
#include <shogun/io/SGIO.h>
#include <shogun/kernel/Kernel.h>

#include <shogun/features/Features.h>
#include <shogun/features/CombinedFeatures.h>

namespace shogun
{
class CFeatures;
class CCombinedFeatures;
class CList;
class CListElement;
class CProductKernel : public CKernel
{
    public:
        CProductKernel(int32_t size=10);

        virtual ~CProductKernel();

        virtual bool init(CFeatures* lhs, CFeatures* rhs);

        virtual void cleanup();

        virtual EKernelType get_kernel_type()
        {
            return K_PRODUCT;
        }

        virtual EFeatureType get_feature_type()
        {
            return F_UNKNOWN;
        }

        virtual EFeatureClass get_feature_class()
        {
            return C_COMBINED;
        }

        virtual const char* get_name() const { return "ProductKernel"; }

        void list_kernels();

        inline CKernel* get_first_kernel()
        {
            return (CKernel*) kernel_list->get_first_element();
        }

        inline CKernel* get_first_kernel(CListElement*& current)
        {
            return (CKernel*) kernel_list->get_first_element(current);
        }

        inline CKernel* get_kernel(int32_t idx)
        {
            CKernel * k = get_first_kernel();
            for (int32_t i=0; i<idx; i++)
            {
                SG_UNREF(k);
                k = get_next_kernel();
            }
            return k;
        }

        inline CKernel* get_last_kernel()
        {
            return (CKernel*) kernel_list->get_last_element();
        }

        inline CKernel* get_next_kernel()
        {
            return (CKernel*) kernel_list->get_next_element();
        }

        inline CKernel* get_next_kernel(CListElement*& current)
        {
            return (CKernel*) kernel_list->get_next_element(current);
        }

        inline bool insert_kernel(CKernel* k)
        {
            ASSERT(k);
            adjust_num_lhs_rhs_initialized(k);

            if (!(k->has_property(KP_LINADD)))
                unset_property(KP_LINADD);

            return kernel_list->insert_element(k);
        }

        inline bool append_kernel(CKernel* k)
        {
            ASSERT(k);
            adjust_num_lhs_rhs_initialized(k);

            if (!(k->has_property(KP_LINADD)))
                unset_property(KP_LINADD);

            return kernel_list->append_element(k);
        }


        inline bool delete_kernel()
        {
            CKernel* k=(CKernel*) kernel_list->delete_element();
            SG_UNREF(k);

            if (!k)
            {
                num_lhs=0;
                num_rhs=0;
            }

            return (k!=NULL);
        }


        inline int32_t get_num_subkernels()
        {
            return kernel_list->get_num_elements();
        }

        virtual bool has_features()
        {
            return initialized;
        }

        virtual void remove_lhs();

        virtual void remove_rhs();

        virtual void remove_lhs_and_rhs();

        bool precompute_subkernels();

        CProductKernel* KernelToProductKernel(shogun::CKernel* n)
        {
            return dynamic_cast<CProductKernel*>(n);
        }

        SGMatrix<float64_t> get_parameter_gradient(TParameter* param,
                CSGObject* obj, index_t index);

        inline CList* get_list() {SG_REF(kernel_list); return kernel_list;}

    protected:
        virtual float64_t compute(int32_t x, int32_t y);

        inline void adjust_num_lhs_rhs_initialized(CKernel* k)
        {
            ASSERT(k);

            if (k->get_num_vec_lhs())
            {
                if (num_lhs)
                    ASSERT(num_lhs==k->get_num_vec_lhs());
                num_lhs=k->get_num_vec_lhs();

                if (!get_num_subkernels())
                {
                    initialized=true;
#ifdef USE_SVMLIGHT
                    cache_reset();
#endif //USE_SVMLIGHT
                }
            }
            else
                initialized=false;

            if (k->get_num_vec_rhs())
            {
                if (num_rhs)
                    ASSERT(num_rhs==k->get_num_vec_rhs());
                num_rhs=k->get_num_vec_rhs();

                if (!get_num_subkernels())
                {
                    initialized=true;
#ifdef USE_SVMLIGHT
                    cache_reset();
#endif //USE_SVMLIGHT
                }
            }
            else
                initialized=false;
        }

    private:
        void init();

    protected:
        CList* kernel_list;
        bool initialized;
};
}
#endif /* _PRODUCTKERNEL_H__ */