PolyFeatures.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.
 *
 * Written (W) 2009 Jonas Behr
 * Copyright (C) 2009 Fraunhofer Institute FIRST and Max-Planck-Society
 */
#ifndef _POLYFEATURES__H__
#define _POLYFEATURES__H__

#include "lib/common.h"
#include "features/DotFeatures.h"
#include "features/SimpleFeatures.h"


namespace shogun
{
class CPolyFeatures : public CDotFeatures
{
    public:
        CPolyFeatures(CSimpleFeatures<float64_t>* feat, int32_t degree, bool normalize);

        virtual ~CPolyFeatures();

        CPolyFeatures(const CPolyFeatures & orig){ 
            SG_PRINT("CPolyFeatures:\n");
            SG_NOTIMPLEMENTED;};

        inline virtual int32_t get_dim_feature_space()
        {
            return m_output_dimensions;
        }

        virtual inline int32_t get_nnz_features_for_vector(int32_t num)
        {
            return m_output_dimensions;
        }

        inline virtual EFeatureType get_feature_type()
        {
            return F_UNKNOWN;
        }

        inline virtual EFeatureClass get_feature_class()
        {
            return C_POLY;
        }

        inline virtual int32_t get_num_vectors()
        {
            if (m_feat)
                return m_feat->get_num_vectors();
            else
                return 0;

        }

        virtual float64_t dot(int32_t vec_idx1, int32_t vec_idx2);

        inline virtual int32_t get_size()
        {
            return sizeof(float64_t);
        }

        CFeatures* duplicate() const;

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

        float64_t dense_dot(int32_t vec_idx1, float64_t* vec2, int32_t vec2_len);

        void add_to_dense_vec(float64_t alpha, int32_t vec_idx1, float64_t* vec2, int32_t vec2_len, bool abs_val);

        struct poly_feature_iterator
        {
            uint16_t* vec;
            int32_t vidx;
            int32_t vlen;
            bool vfree;

            int32_t index;

        };

        virtual void* get_feature_iterator(int32_t vector_index)
        {
            SG_NOTIMPLEMENTED;
            return NULL;
        }

        virtual bool get_next_feature(int32_t& index, float64_t& value, void* iterator)
        {
            SG_NOTIMPLEMENTED;
            return NULL;
        }

        virtual void free_feature_iterator(void* iterator)
        {
            SG_NOTIMPLEMENTED;
        }

    protected: 

        void store_normalization_values();

        void store_multi_index();

        void enumerate_multi_index(const int32_t feat_idx, uint16_t** index, uint16_t* exponents, const int32_t degree);
        void store_multinomial_coefficients();

        int32_t bico2(int32_t n, int32_t k);

        int32_t  bico(int32_t n, int32_t k);

        int32_t calc_feature_space_dimensions(int32_t N, int32_t D);

        int32_t multinomialcoef(int32_t* exps, int32_t len);

        float64_t gammln(float64_t xx);

        float64_t factln(int32_t n);

    protected:

        CSimpleFeatures<float64_t>* m_feat;
        int32_t m_degree;
        bool m_normalize;
        int32_t m_input_dimensions;
        int32_t m_output_dimensions;
        uint16_t* m_multi_index;
        float64_t* m_multinomial_coefficients; 
        float32_t* m_normalization_values; 

};
}
#endif // _POLYFEATURES__H__