onelayerffnn.h

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#ifndef __ONELAYERFFNN_H 
#define __ONELAYERFFNN_H

#include "feedforwardnn.h"
#include "randomgenerator.h"

/// simple one layer neural network with configurable activation function
class OneLayerFFNN : public FeedForwardNN {
public: 
  /**
     Uses linear activation function
     @param eps learning rate
     @param factor_bias learning rate factor for bias learning     
  */
  OneLayerFFNN(double eps, 
               double factor_bias = 0.1)
    : eps(eps), factor_bias(factor_bias){ 
    actfun  = linear;
    dactfun = dlinear;
      
    initialised = false;  
  }
  /**
     @param eps learning rate
     @param factor_bias learning rate factor for bias learning
     @param actfun callback activation function (see FeedForwardNN)
     @param dactfun callback for first derivative of the activation function
  */
  OneLayerFFNN(double eps, 
               double factor_bias,
               ActivationFunction actfun, 
               ActivationFunction dactfun)
    : eps(eps), factor_bias(factor_bias), actfun(actfun), dactfun(dactfun) { 
    initialised = false;  
  }
  virtual ~OneLayerFFNN(){ }

  /* initialisation of the network with the given number of input and output units
     @param unit_map defines the approximate response of the network 
       after initialisation (if unit_map=1 the weights are unit matrices).
     @param randGen pointer to random generator, if 0 an new one is used
  */
  virtual void init(unsigned int inputDim, unsigned  int outputDim, 
                    double unit_map = 0.0, RandGen* randGen = 0); 

  virtual const matrix::Matrix process (const matrix::Matrix& input); 

  virtual const matrix::Matrix learn (const matrix::Matrix& input, 
                                      const matrix::Matrix& nom_output, 
                                      double learnRateFactor = 1);

  /// returns the number of input neurons
  virtual unsigned int getInputDim() const { 
    return weights.getN(); 
  }
  /// returns the number of output neurons
  virtual unsigned int getOutputDim() const { 
    return weights.getM(); 
  }

  virtual const matrix::Matrix& getWeights() const { return weights; }
  virtual const matrix::Matrix& getBias()    const { return bias; }

  /// damps the weights and the biases by multiplying (1-damping)
  virtual void damp(double damping){
    weights *= (1-damping);
    bias    *= (1-damping);
  }

  /**************  STOREABLE **********************************/
  /// stores the layer binary into file stream
  bool store(FILE* f) const;
  /// restores the layer binary from file stream
  bool restore(FILE* f);

  /************** CONFIGURABLE INTERFACE ************************/
  virtual paramkey getName() const {
    return paramkey("onelayerffnn");
  }

  virtual paramval getParam(const paramkey key) const {
    if(key == "eps") return eps;
    else return 0.0;
  }
  
  virtual bool setParam(const paramkey key, paramval val){
    if( key == "eps") { 
      eps = val;
      return true;
    } else return false;
  }

  virtual paramlist getParamList() const{
    paramlist l;
    l.push_back(std::pair<paramkey, paramval> ("eps", eps));
    return l;
  }


private:
  double eps;
  double factor_bias;
  ActivationFunction actfun;  ///< callback activation function
  ActivationFunction dactfun; ///< first derivative of the activation function  

private:
  bool initialised;
  matrix::Matrix weights;
  matrix::Matrix bias;
};

#endif

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