base.hpp

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#ifndef SSMPACK_FILTER_RESAMPLER_BASE
#define SSMPACK_FILTER_RESAMPLER_BASE

#include <armadillo>

namespace ssmkit {
namespace filter {
namespace resampler {

template<class T>
class BaseResampler;

template <template <class> class Method, class Criterion>
class BaseResampler<Method<Criterion>> {
  protected:
  Criterion criterion_;
  
  public:
   BaseResampler(Criterion criterion) : criterion_(std::move(criterion)) {}

   template <class Particles, class Weights>
   void operator()(Particles &pars, Weights &w) {
     // return if resampling criterion is false
     if (!criterion_(w))
       return;

     // generate ordered numbers
     auto u = static_cast<Method<Criterion> *>(this)
                  ->generateOrderedNumbers(w.n_rows);

     auto ws = arma::cumsum(w);
     auto u_it = u.begin();

     Particles old_pars = pars;

     pars.each_col([&u_it, &old_pars,
                    &ws](arma::Col<typename Particles::elem_type> &col) {
       col = old_pars.col(
           static_cast<arma::uvec>(arma::find(ws > *u_it++, 1, "first"))(0));
     });

     w.fill(1.0 / w.n_rows);
   }
};

} // namespace resampler
} // namespace filter
} // namespace ssmkit
#endif //SSMPACK_FILTER_RESAMPLER_IDENTITY