SGSparseVector.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) 2013 Thoralf Klein
 * Written (W) 2012 Fernando José Iglesias García
 * Written (W) 2010,2012 Soeren Sonnenburg
 * Copyright (C) 2010 Berlin Institute of Technology
 * Copyright (C) 2012 Soeren Sonnenburg
 */

#ifndef __SGSPARSEVECTOR_H__
#define __SGSPARSEVECTOR_H__

#include <shogun/lib/config.h>
#include <shogun/lib/DataType.h>
#include <shogun/lib/SGReferencedData.h>

namespace shogun
{
    class CFile;

template <class T> struct SGSparseVectorEntry
{
    index_t feat_index;
    T entry;
};

template <class T> class SGSparseVector : public SGReferencedData
{
public:
    SGSparseVector();

    SGSparseVector(SGSparseVectorEntry<T>* feats, index_t num_entries,
            bool ref_counting=true);

    SGSparseVector(index_t num_entries, bool ref_counting=true);

    SGSparseVector(const SGSparseVector& orig);

    virtual ~SGSparseVector();

    T dense_dot(T alpha, T* vec, int32_t dim, T b);

    template<typename ST> T dense_dot(SGVector<ST> vec);

    T sparse_dot(const SGSparseVector<T>& v);

    static T sparse_dot(const SGSparseVector<T>& a, const SGSparseVector<T>& b);

    inline SGSparseVector<T> get()
    {
        return *this;
    }

    int32_t get_num_dimensions();

    void sort_features(bool stable_pointer = false);

    T get_feature(int32_t index);

    SGVector<T> get_dense(int32_t dimension);

    SGVector<T> get_dense();

    SGSparseVector<T> clone() const;

    void load(CFile* loader);

    void save(CFile* saver);


    void display_vector(const char* name="vector",
            const char* prefix="");

protected:
    virtual void copy_data(const SGReferencedData& orig);

    virtual void init_data();

    virtual void free_data();

    static int32_t cmp_dot_prod_symmetry_fast(index_t alen, index_t blen);

    static T dot_prod_asymmetric(const SGSparseVector<T>& a, const SGSparseVector<T>& b);

    static T dot_prod_symmetric(const SGSparseVector<T>& a, const SGSparseVector<T>& b);

public:
    index_t num_feat_entries;

    SGSparseVectorEntry<T>* features;

};

}

#endif // __SGSPARSEVECTOR_H__