// [[Rcpp::export]]
Rcpp::List cpp_weighted_knn(arma::mat x,
arma::mat query,
arma::vec weights,
const char sortDirection,
const std::size_t k) {
std::size_t nVars = weights.size();
std::size_t nQuery = query.n_rows;
arma::mat retDist(nQuery, k);
arma::umat retOrder(nQuery, k);
arma::colvec tmpDist(x.n_rows);
tmpDist.fill(0);
arma::uvec order(x.n_rows);
for (std::size_t i=0;i<nQuery;++i) {
for (std::size_t j=0;j <nVars;++j) {
tmpDist = tmpDist + abs(weights(j) * (x.col(j) - query(i, j)));
}
order = arma::sort_index(tmpDist, sortDirection);
for (std::size_t l=0; l<k;++l) {
retDist(i, l) = tmpDist(order(l));
retOrder(i, l) = order(l) + 1;
}
tmpDist.fill(0);
}
return Rcpp::List::create(
Rcpp::Named("distance") = retDist,
Rcpp::Named("order") = retOrder
);
}
// [[Rcpp::export]]
Rcpp::List get_nearest_Elements(arma::mat mNew,
arma::mat mRef,
arma::vec vWeights,
int nCases) {
try {
// number of variables in model
int nVars = vWeights.size();
// n new cases
int nNewCases = mNew.n_rows;
// allocate distance and order matrix
arma::mat retDist(nNewCases, nCases);
arma::umat retOrder(nNewCases, nCases);
// allocate tmp vector
arma::colvec tmpDist(mRef.n_rows);
arma::uvec order(mRef.n_rows);
for (int i=0; i<nNewCases; ++i) { // loop over cases
for (int j=0; j<nVars; ++j) { // loop over variables
tmpDist = tmpDist + abs(vWeights(j) * (mRef.col(j) - mNew(i, j))); //
} // end loop variables
order = arma::sort_index(tmpDist);
for (int k=0;k<nCases; ++k) {
// write distance to final matrix
retDist(i, k) = tmpDist(order(k));
// write order to final matrix
retOrder(i, k) = order(k) + 1;
}
// reset tmp distance vector
tmpDist = arma::zeros<arma::vec>(mRef.n_rows);
} // end loop cases
return Rcpp::List::create(
Rcpp::Named("distance") = retDist,
Rcpp::Named("order") = retOrder
);
} catch(std::exception &ex) {
forward_exception_to_r(ex);
} catch(...) {
::Rf_error("c++ exception (unknown reason)");
}
// never go here
return NA_REAL;
}