DataVsModelResiduals.icpp

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namespace ModelFitting {
 
template <typename DataType, typename ModelType, typename WeightType, typename Comparator>
DataVsModelResiduals<DataType,ModelType,WeightType,Comparator>::DataVsModelResiduals(
                      DataType data, ModelType model, WeightType weight, Comparator comparator)
          : m_data{std::move(data)}, m_model{std::move(model)}, m_weight{std::move(weight)},
            m_comparator(std::move(comparator)), m_residual_no{DataTraits::size(m_data)} {
  if (DataTraits::size(m_data) != ModelTraits::size(m_model)) {
    throw Elements::Exception() << "Data size (" << DataTraits::size(m_data)
        << ") is different than model size (" << ModelTraits::size(m_model) << ")";
  }
  if (DataTraits::size(m_data) != WeightTraits::size(m_weight)) {
    throw Elements::Exception() << "Data size (" << DataTraits::size(m_data)
        << ") is different than weight size (" << WeightTraits::size(m_weight) << ")";
  }
}
 
template <typename DataType, typename ModelType, typename WeightType, typename Comparator>
DataVsModelResiduals<DataType,ModelType,WeightType,Comparator>::~DataVsModelResiduals() = default;
 
template <typename DataType, typename ModelType, typename WeightType, typename Comparator>
std::size_t DataVsModelResiduals<DataType,ModelType,WeightType,Comparator>::numberOfResiduals() const {
  return m_residual_no;
}
 
template <typename DataType, typename ModelType, typename WeightType, typename Comparator>
void DataVsModelResiduals<DataType,ModelType,WeightType,Comparator>::populateResidualBlock(IterType output_iter) {
  auto data_iter = DataTraits::begin(m_data);
  auto model_iter = ModelTraits::begin(m_model);
  auto weight_iter = WeightTraits::begin(m_weight);
//  double test = 0;
//  static double diff = 0;
  for (; data_iter!=DataTraits::end(m_data); ++data_iter, ++model_iter, ++weight_iter, ++output_iter) {
    *output_iter = m_comparator(*data_iter, *model_iter, *weight_iter);
//    test += *output_iter;
  }
//  std::cout << test << " -- " << test-diff << "\n";
//  diff = test;
}
 
// NOTE TO DEVELOPERS:
//
// The following factory function looks (and is) complicated, but it greatly
// simplifies the code using the library. For example, using the factory method,
// the code for creating a DataVsModelResiduals looks like:
//
// std::vector<double> data = ...;
// std::vector<double> model = ...;
// std::vector<double> weights = ...;
// auto res_prov = createDataVsModelResiduals(data, model, weights, ChiSquareComparator{});
//
// The equivalent command when using directly the constructor would be:
//
// std::vector<double> data = ...;
// std::vector<double> model = ...;
// std::vector<double> weights = ...;
// unique_ptr<DataVsModelResiduals<std::vector<double>, std::vector<double>,
//                                 std::vector<double>, ChiSquareComparator>> res_prov {
//   new DataVsModelResiduals<std::vector<double>, std::vector<double>,
//                            std::vector<double>, ChiSquareComparator> {
//          y_data, model, weight, ChiSquareComparator{}
//   }
// };
//
// The above shows the importance of the existence of this factory. Here are
// some tips, to help you understand how the function works:
//
// - The function perfect-forwards its parameters to the constructor, so it can
//   be the exact equivalent with calling the constructor, regardless the
//   r-valueness or l-valueness of the parameters. If you don't know what the
//   perfect forwarding is, search the internet for a good explanation before
//   you continue trying to understand this code.
//
// - The template parameters of the factory method are NOT the same with the ones
//   of the DataVsModelResiduals object being created. This is a result of the
//   use of the perfect forwarding. More precisely, the template types of the
//   factory method are lvalue or rvalue REFERENCES (which is how perfect
//   forwarding works), when the template types of the DataVsModelResiduals are
//   the actual types (and no references to them).
//
// - The "typename std::remove_reference<...>::type" (which is used a lot bellow)
//   simply removes any reference from the type, creating the proper template
//   parameter for the DataVsModelResiduals class. The keyword "typename" has to
//   be used because, during the first passage, the compiler will fail to recognize
//   that the "std::remove_reference<...>::type" is an existing type (because
//   it contains a template parameter itself).
//
// I hope the above will help you to understand how the factory method works.
template <typename DataType, typename ModelType, typename WeightType, typename Comparator>
std::unique_ptr<DataVsModelResiduals<typename std::remove_reference<DataType>::type,
                                     typename std::remove_reference<ModelType>::type,
                                     typename std::remove_reference<WeightType>::type,
                                     typename std::remove_reference<Comparator>::type>
               > createDataVsModelResiduals(DataType&& data, ModelType&& model,
                                            WeightType&& weight, Comparator&& comparator) {
  return std::unique_ptr<DataVsModelResiduals<typename std::remove_reference<DataType>::type,
                                              typename std::remove_reference<ModelType>::type,
                                              typename std::remove_reference<WeightType>::type,
                                              typename std::remove_reference<Comparator>::type>
                        > {
    new DataVsModelResiduals<typename std::remove_reference<DataType>::type,
                             typename std::remove_reference<ModelType>::type,
                             typename std::remove_reference<WeightType>::type,
                             typename std::remove_reference<Comparator>::type> {
        std::forward<DataType>(data), std::forward<ModelType>(model),
        std::forward<WeightType>(weight), std::forward<Comparator>(comparator)
    }
  };
}
 
} // end of namespace ModelFitting