lmetric_search.hpp

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#ifndef MLPACK_METHODS_CF_LMETRIC_SEARCH_HPP
#define MLPACK_METHODS_CF_LMETRIC_SEARCH_HPP

#include <mlpack/prereqs.hpp>
#include <mlpack/methods/neighbor_search/neighbor_search.hpp>
#include <mlpack/core/metrics/lmetric.hpp>

namespace mlpack {
namespace cf {

template<int TPower>
class LMetricSearch
{
 public:
  using NeighborSearchType = neighbor::NeighborSearch<
      neighbor::NearestNeighborSort,
      metric::LMetric<TPower, true>>;

  LMetricSearch(const arma::mat& referenceSet) : neighborSearch(referenceSet)
  { }

  void Search(const arma::mat& query, const size_t k,
              arma::Mat<size_t>& neighbors, arma::mat& similarities)
  {
    neighborSearch.Search(query, k, neighbors, similarities);

    // Calculate similarities from L_p distance. We restrict that similarities
    // are not larger than one.
    similarities = 1.0 / (1.0 + similarities);
  }

 private:
  NeighborSearchType neighborSearch;
};

using EuclideanSearch = LMetricSearch<2>;

} // namespace cf
} // namespace mlpack

#endif