network_init.hpp

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#ifndef MLPACK_METHODS_ANN_INIT_RULES_NETWORK_INIT_HPP
#define MLPACK_METHODS_ANN_INIT_RULES_NETWORK_INIT_HPP

#include <mlpack/prereqs.hpp>
#include <mlpack/methods/ann/layer/layer.hpp>

#include "init_rules_traits.hpp"

namespace mlpack {
namespace ann  {

template<typename InitializationRuleType>
class NetworkInitialization
{
 public:
  NetworkInitialization(
      const InitializationRuleType& initializeRule = InitializationRuleType()) :
      initializeRule(initializeRule)
  {
    // Nothing to do here.
  }

  template <typename eT>
  void Initialize(const std::vector<Layer<arma::Mat<eT>>*>& network,
                  arma::Mat<eT>& parameters,
                  size_t parameterOffset = 0)
  {
    // Determine the total number of parameters/weights of the given network.
    if (parameters.is_empty())
    {
      size_t weights = 0;
      for (size_t i = 0; i < network.size(); ++i)
        weights += network[i]->WeightSize();

      parameters.set_size(weights, 1);
    }

    // Initialize the network layer by layer or the complete network.
    if (ann::InitTraits<InitializationRuleType>::UseLayer)
    {
      for (size_t i = 0, offset = parameterOffset; i < network.size(); ++i)
      {
        // Initialize the layer with the specified parameter/weight
        // initialization rule.
        const size_t weight = network[i]->WeightSize();
        arma::Mat<eT> tmp = arma::mat(parameters.memptr() + offset,
            weight, 1, false, false);
        initializeRule.Initialize(tmp, tmp.n_elem, 1);

        // Increase the parameter/weight offset for the next layer.
        offset += weight;
      }
    }
    else
    {
      initializeRule.Initialize(parameters, parameters.n_elem, 1);
    }
  }

 private:
  InitializationRuleType initializeRule;
}; // class NetworkInitialization

} // namespace ann
} // namespace mlpack

#endif