Hi Gang:
I was recently explaining to someone that functions like Rcpp::rnorm only
take scalars. Since the R function takes vectors, the OP was asking me
why?
I didn¹t have a good answer. This morning, I started thinking about it
and I realized this could easily be handled by over-loading (I know: that
is
why they call me Mr. Excitement ;o)
I don¹t know if these overloads would have to be written by hand or could
be
auto-generated. If the latter, then I guess it is a feature request. If
not,
then probably a friendly suggestion. But, here is a short example that
shows
it is feasible if there is any doubt.
Happy Easter!
Rodney
The R transcript...
> require(Rcpp)
Loading required package: Rcpp
> sourceCpp('rnorm.cpp')
> set.seed(21)
> rnorm(6, 0, 0.01/1:2)
[1] 0.007930132 0.002611256 0.017462222 -0.006356681 0.021973895
[6] 0.002165654
> set.seed(21)
> test0(6, 0, 0.01/1:2)
[1] 0.007930132 0.002611256 0.017462222 -0.006356681 0.021973895
[6] 0.002165654
> set.seed(21)
> rnorm(6, 0:1, 0.01)
[1] 0.007930132 1.005222513 0.017462222 0.987286639 0.021973895 1.004331308
> set.seed(21)
> test0(6, 0:1, 0.01)
[1] 0.007930132 1.005222513 0.017462222 0.987286639 0.021973895 1.004331308
> set.seed(21)
> rnorm(6, 0:2, 0.01/1:2)
[1] 0.007930132 1.002611256 2.017462222 -0.006356681 1.021973895
[6] 2.002165654
> set.seed(21)
> test0(6, 0:2, 0.01/1:2)
[1] 0.007930132 1.002611256 2.017462222 -0.006356681 1.021973895
[6] 2.002165654
rnorm.cpp begin
#include <Rcpp.h>
Rcpp::NumericVector rnorm(int n, Rcpp::NumericVector mean,
Rcpp::NumericVector sd) {
const int k_mu=mean.size(), k_sd=sd.size();
Rcpp::NumericVector ret(n);
for(int i=0; i<n; ++i) ret[i]=Rcpp::rnorm(1, mean[i%k_mu],
sd[i%k_sd])[0];
return ret;
}
// [[Rcpp::export]]
Rcpp::NumericVector test0(int n, Rcpp::NumericVector mean,
Rcpp::NumericVector sd) {
return rnorm(n, mean, sd);
}
rnorm.cpp end
rnorm.R begin
require(Rcpp)
sourceCpp('rnorm.cpp')
set.seed(21)
rnorm(6, 0, 0.01/1:2)
set.seed(21)
test0(6, 0, 0.01/1:2)
set.seed(21)
rnorm(6, 0:1, 0.01)
set.seed(21)
test0(6, 0:1, 0.01)
set.seed(21)
rnorm(6, 0:2, 0.01/1:2)
set.seed(21)
test0(6, 0:2, 0.01/1:2)
rnorm.R end
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