facilities.hpp

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#ifndef MLPACK_CORE_CV_METRICS_FACILITIES_HPP
#define MLPACK_CORE_CV_METRICS_FACILITIES_HPP

#include <mlpack/core.hpp>
#include <mlpack/core/metrics/lmetric.hpp>

namespace mlpack {
namespace cv {

template<typename DataType>
void AssertSizes(const DataType& data,
                 const arma::Row& labels,
                 const std::string& callerDescription)
{
  if (data.n_cols != labels.n_elem)
  {
    std::ostringstream oss;
    oss << callerDescription << ": number of points (" << data.n_cols << ") "
        << "does not match number of labels (" << labels.n_elem << ")!"
        << std::endl;
    throw std::invalid_argument(oss.str());
  }
}

template<typename DataType, typename Metric>
DataType PairwiseDistances(const DataType& data,
                           const Metric& metric)
{
  DataType distances = DataType(data.n_cols, data.n_cols, arma::fill::none);
  for (size_t i = 0; i < data.n_cols; i++)
  {
    for (size_t j = 0; j < i; j++)
    {
      distances(i, j) = metric.Evaluate(data.col(i), data.col(j));
      distances(j, i) = distances(i, j);
    }
  }
  distances.diag().zeros();
  return distances;
}

} // namespace cv
} // namespace mlpack

#endif