nnlayer.h

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// -*- C++ -*-
#ifndef __LEMGA_NNLAYER_H__
#define __LEMGA_NNLAYER_H__

#include <vector>
#include "learnmodel.h"

namespace lemga {

class NNLayer : public LearnModel {
    mutable REAL stored_sigmoid;

public:
    typedef std::vector<REAL> WVEC; 
    typedef std::vector<REAL> DVEC; 

protected:
    REAL w_min, w_max;
    WVEC w;   
    WVEC dw;  
    mutable DVEC sig_der;  // f'(wsum)

public:
    explicit NNLayer (UINT n_in = 0, UINT n_unit = 0);
    explicit NNLayer (std::istream& is) { is >> *this; }

    virtual const id_t& id () const;
    virtual NNLayer* create () const { return new NNLayer(); }
    virtual NNLayer* clone () const { return new NNLayer(*this); }

    UINT size () const { return n_output(); }

    void set_weight_range (REAL min, REAL max) {
        assert(min < max);
        w_min = min; w_max = max;
    }
    const WVEC& weight () const { return w; }
    void set_weight (const WVEC&);

    const WVEC& gradient () const { return dw; }
    void clear_gradient ();

    virtual void initialize ();
    virtual REAL train () { OBJ_FUNC_UNDEFINED("train"); }
    virtual Output operator() (const Input& x) const {
        Output y(n_output());
        feed_forward(x, y);
        return y;
    }

    void feed_forward (const Input&, Output&) const;
    void back_propagate (const Input&, const DVEC&, DVEC&);

protected:
    virtual REAL sigmoid (REAL) const;
    virtual REAL sigmoid_deriv (REAL) const;
    virtual bool serialize (std::ostream&, ver_list&) const;
    virtual bool unserialize (std::istream&, ver_list&,
                              const id_t& = empty_id);
};

} // namespace lemga

#ifdef  __NNLAYER_H__
#warning "This header file may conflict with another `nnlayer.h' file."
#endif
#define __NNLAYER_H__
#endif

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