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 <shogun/lib/config.h>

#include <shogun/lib/common.h>
#include <shogun/features/DotFeatures.h>
#include <shogun/features/DenseFeatures.h>


namespace shogun
{
class CPolyFeatures : public CDotFeatures
{
    public:
        CPolyFeatures();

        CPolyFeatures(CDenseFeatures<float64_t>* feat, int32_t degree, bool normalize);

        virtual ~CPolyFeatures();

        CPolyFeatures(const CPolyFeatures & orig);

        virtual int32_t get_dim_feature_space() const;

        virtual int32_t get_nnz_features_for_vector(int32_t num);

        virtual EFeatureType get_feature_type() const;

        virtual EFeatureClass get_feature_class() const;

        virtual int32_t get_num_vectors() const;

        virtual float64_t dot(int32_t vec_idx1, CDotFeatures* df, int32_t vec_idx2);

        CFeatures* duplicate() const;

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

        float64_t dense_dot(int32_t vec_idx1, const 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);

        #ifndef DOXYGEN_SHOULD_SKIP_THIS

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

            int32_t index;

        };
        #endif

        virtual void* get_feature_iterator(int32_t vector_index);

        virtual bool get_next_feature(int32_t& index, float64_t& value,
                void* iterator);

        virtual void free_feature_iterator(void* iterator);

    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:

        CDenseFeatures<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;
    private:
        index_t multi_index_length;
        index_t multinomial_coefficients_length;
        index_t normalization_values_length;

        void register_parameters();
};
}
#endif // _POLYFEATURES__H__