HashedWDFeatures.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 _HASHEDWDFEATURES_H___
#define _HASHEDWDFEATURES_H___

#include "lib/common.h"
#include "features/DotFeatures.h"
#include "features/StringFeatures.h"
#include "lib/Hash.h"

namespace shogun
{
template <class ST> class CStringFeatures;

class CHashedWDFeatures : public CDotFeatures
{
    public:

        CHashedWDFeatures(CStringFeatures<uint8_t>* str, int32_t start_order,
                int32_t order,  int32_t from_order, int32_t hash_bits=12);

        CHashedWDFeatures(const CHashedWDFeatures & orig);

        virtual ~CHashedWDFeatures();

        inline virtual int32_t get_dim_feature_space()
        {
            return w_dim;
        }

        virtual float64_t dot(int32_t vec_idx1, int32_t vec_idx2);

        virtual float64_t dense_dot(int32_t vec_idx1, 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);

        virtual inline int32_t get_nnz_features_for_vector(int32_t num)
        {
            int32_t vlen=-1;
            bool free_vec;
            uint8_t* vec=strings->get_feature_vector(num, vlen, free_vec);
            strings->free_feature_vector(vec, num, free_vec);
            return degree*vlen;
        }

        struct hashed_wd_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;
        }

        virtual CFeatures* duplicate() const;

        inline virtual EFeatureType get_feature_type()
        {
            return F_UNKNOWN;
        }

        inline virtual EFeatureClass get_feature_class()
        {
            return C_WD;
        }

        inline virtual int32_t get_num_vectors()
        {
            return num_strings;
        }

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

        void set_normalization_const(float64_t n=0);

        inline float64_t get_normalization_const()
        {
            return normalization_const;
        }

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

    protected:

        void set_wd_weights();

    protected:
        CStringFeatures<uint8_t>* strings;

        int32_t degree;
        int32_t start_degree;
        int32_t from_degree;
        int32_t string_length;
        int32_t num_strings;
        int32_t alphabet_size;
        int32_t w_dim;
        int32_t partial_w_dim;
        float64_t* wd_weights;
        uint32_t mask;
        int32_t m_hash_bits;

        float64_t normalization_const;
};
}
#endif // _HASHEDWDFEATURES_H___