void KnnAccuracy(const arma::mat& dataset,const arma::Row<size_t>& labels, size_t k)
{
  arma::Row<size_t> uniqueLabels = arma::unique(labels);

  arma::Mat<size_t> neighbors;
  arma::mat distances;

  neighbor::KNN knn;

  knn.Train(dataset);
  knn.Search(k, neighbors, distances);

  //Keep count.
  double count = 0.0;

  for (size_t i = 0; i < dataset.n_cols; i++)
  {
    arma::Row<size_t> Map;
    Map.zeros(uniqueLabels.n_cols);

    for (size_t j=0; j < k; j++)
      Map(labels(neighbors(j,i)))++;

    arma::vec ind = arma::conv_to<arma::vec>::from(arma::find(Map == arma::max(Map)));
    if (ind(0) == labels(i))
        count++;
  }

  std::cout << "Accuracy : " << (count / dataset.n_cols) * 100  << std::endl;
}