SparsePolyFeatures.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) 2010 Soeren Sonnenburg
 * Copyright (C) 2010 Berlin Institute of Technology
 */
#ifndef _SPARSEPOLYFEATURES__H__
#define _SPARSEPOLYFEATURES__H__

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

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

        CSparsePolyFeatures(CSparseFeatures<float64_t>* feat, int32_t degree, bool normalize, int32_t hash_bits);

        virtual ~CSparsePolyFeatures();

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

        inline virtual int32_t get_dim_feature_space() const
        {
            return m_output_dimensions;
        }

        virtual inline int32_t get_nnz_features_for_vector(int32_t num)
        {
            int32_t vlen;
            SGSparseVector<float64_t> vec=m_feat->get_sparse_feature_vector(num);
            vlen=vec.num_feat_entries;
            m_feat->free_feature_vector(vec, num);
            return vlen*(vlen+1)/2;
        }

        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() const
        {
            if (m_feat)
                return m_feat->get_num_vectors();
            else
                return 0;

        }

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

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

        #ifndef DOXYGEN_SHOULD_SKIP_THIS

        struct sparse_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)
        {
            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;
        }

        CFeatures* duplicate() const;

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

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

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

    protected: 
        void store_normalization_values();

    protected:
        CSparseFeatures<float64_t>* m_feat;
        int32_t m_degree;
        bool m_normalize;
        int32_t m_input_dimensions;
        int32_t m_output_dimensions;
        float64_t* m_normalization_values; 
        uint32_t mask;
        int32_t m_hash_bits;
    private:
        void init();

    private:
        int32_t m_normalization_values_len;

};
}
#endif // _SPARSEPOLYFEATURES__H__