MLP.hpp

#ifndef MLP__H
#define MLP__H

#include <dynet/nodes.h>
#include <dynet/dynet.h>
#include <dynet/training.h>
#include <dynet/timing.h>
#include <dynet/expr.h>
#include "FeatureModel.hpp"

class MLP
{
  public :

  using Examples = std::pair< std::vector<int>, std::vector<std::pair<int, FeatureModel::FeatureDescription> > >;

  enum Activation
  {
    SIGMOID,
    TANH,
    RELU,
    ELU,
    LINEAR,
    SPARSEMAX,
    CUBE,
    SOFTMAX
  };

  static std::string activation2str(Activation a);
  static Activation str2activation(std::string s);

  struct Layer
  {
    int input_dim;
    int output_dim;

    float dropout_rate;
    Activation activation;

    Layer(int input_dim, int output_dim,
      float dropout_rate, Activation activation);
    void print(FILE * file);
  };

  private :

  static const unsigned int MAXLOOKUPSIZE = 200000;

  std::vector<Layer> layers;
  std::vector< std::vector<dynet::Parameter> > parameters;
  std::map< Dict*, std::pair<dynet::LookupParameter, std::map<void*, unsigned int> > > lookupParameters;

  dynet::ParameterCollection model;
  dynet::AmsgradTrainer trainer;
  bool trainMode;
  bool dropoutActive;

  private :

  void addLayerToModel(Layer & layer);
  void checkLayersCompatibility();
  dynet::DynetParams & getDefaultParams();
  dynet::Expression featValue2Expression(dynet::ComputationGraph & cg, const FeatureModel::FeatureValue & fv);
  dynet::Expression run(dynet::ComputationGraph & cg, dynet::Expression x);
  inline dynet::Expression activate(dynet::Expression h, Activation f);
  void printParameters(FILE * output);
  void saveStruct(const std::string & filename);
  void saveParameters(const std::string & filename);
  void loadStruct(const std::string & filename);
  void loadParameters(const std::string & filename);
  void load(const std::string & filename);

  public :

  MLP(std::vector<Layer> layers);
  MLP(const std::string & filename);
  std::vector<float> predict(FeatureModel::FeatureDescription & fd);

  int trainOnBatch(Examples & examples, int start, int end);
  int getScoreOnBatch(Examples & examples, int start, int end);
  void save(const std::string & filename);
  void printTopology(FILE * output);
};

#endif