RcppExport SEXP rthhist(SEXP x_, SEXP nbins_, SEXP nch_, SEXP nthreads)
{
Rcpp::NumericVector x(x_);
const int n = x.size();
const int nbins = INTEGER(nbins_)[0];
const int nch = INTEGER(nch_)[0];
floublevec dx(x.begin(), x.end());
Rcpp::IntegerVector bincounts(nbins);
Rcpp::NumericVector R_left(1);
Rcpp::NumericVector R_binwidth(1);
#if RTH_OMP
omp_set_num_threads(INT(nthreads));
#elif RTH_TBB
tbb::task_scheduler_init init(INT(nthreads));
#endif
// determine binwidth etc.
thrust::pair<floubleveciter, floubleveciter> mm =
thrust::minmax_element(dx.begin(), dx.end());
flouble left = *(mm.first), right = *(mm.second);
flouble binwidth = (right - left) / nbins;
// form matrix of bin counts, one row per chunk
intvec dbincounts(nch*nbins);
// the heart of the computation, a for_each() loop, one iteration per
// chunk
thrust::counting_iterator<int> seqa(0);
thrust::counting_iterator<int> seqb = seqa + nch;
thrust::for_each(seqa,seqb,
do1chunk(dx.begin(),dbincounts.begin(
),n,nbins,nch,left,binwidth));
// copy result to host and combine the subhistograms
int hbincounts[nch*nbins];
thrust::copy(dbincounts.begin(),dbincounts.end(),hbincounts);
int binnum,chunknum;
for (binnum = 0; binnum < nbins; binnum++) {
int sum = 0;
for (chunknum = 0; chunknum < nch; chunknum++)
sum += hbincounts[chunknum*nbins + binnum];
bincounts[binnum] = sum;
}
REAL(R_left)[0] = (double) left;
REAL(R_binwidth)[0] = (double) binwidth;
return Rcpp::List::create(Rcpp::Named("counts") = bincounts,
Rcpp::Named("left") = R_left,
Rcpp::Named("binwidth") = R_binwidth);
}
extern "C" SEXP rthhist(SEXP x, SEXP nbins_, SEXP nch_, SEXP nthreads)
{
const int n = LENGTH(x);
const int nbins = INTEGER(nbins_)[0];
const int nch = INTEGER(nch_)[0];
floublevec dx(REAL(x), REAL(x)+n);
SEXP bincounts, R_left, R_binwidth;
PROTECT(bincounts = allocVector(INTSXP, nbins));
PROTECT(R_left = allocVector(REALSXP, 1));
PROTECT(R_binwidth = allocVector(REALSXP, 1));
SEXP ret, retnames;
RTH_GEN_NTHREADS(nthreads);
// determine binwidth etc.
thrust::pair<floubleveciter, floubleveciter> mm =
thrust::minmax_element(dx.begin(), dx.end());
flouble left = *(mm.first), right = *(mm.second);
flouble binwidth = (right - left) / nbins;
// form matrix of bin counts, one row per chunk
intvec dbincounts(nch*nbins);
// the heart of the computation, a for_each() loop, one iteration per
// chunk
thrust::counting_iterator<int> seqa(0);
thrust::counting_iterator<int> seqb = seqa + nch;
thrust::for_each(seqa,seqb,
do1chunk(dx.begin(),dbincounts.begin(
), n, nbins, nch, left, binwidth));
// copy result to host and combine the subhistograms
int hbincounts[nch*nbins];
thrust::copy(dbincounts.begin(), dbincounts.end(), hbincounts);
int binnum,chunknum;
for (binnum = 0; binnum < nbins; binnum++) {
int sum = 0;
for (chunknum = 0; chunknum < nch; chunknum++)
sum += hbincounts[chunknum*nbins + binnum];
INTEGER(bincounts)[binnum] = sum;
}
REAL(R_left)[0] = (double) left;
REAL(R_binwidth)[0] = (double) binwidth;
PROTECT(retnames = allocVector(STRSXP, 3));
SET_STRING_ELT(retnames, 0, mkChar("counts"));
SET_STRING_ELT(retnames, 1, mkChar("left"));
SET_STRING_ELT(retnames, 2, mkChar("binwidth"));
PROTECT(ret = allocVector(VECSXP, 3));
SET_VECTOR_ELT(ret, 0, bincounts);
SET_VECTOR_ELT(ret, 1, R_left);
SET_VECTOR_ELT(ret, 2, R_binwidth);
setAttrib(ret, R_NamesSymbol, retnames);
UNPROTECT(5);
return ret;
}
