On Wed, Nov 2, 2011 at 4:00 AM,
<rcpp-devel-requ...@r-forge.wu-wien.ac.at> wrote:
>
>
> 1. in my previous post i used exactly that same constructor you are
> talking about as you can see from the code i posted
Sorry about that, completely missed it...
Using what's below, this should work fine.
> 3. i am not 100% sure but this toy test that i did seem to indicate to me
> that a copy is done regardless by NumericalMatrix. I need to see the code
> for NumericMatrix to be absolutely sure, but i cannot explain things
> otherwise
This is a little tricky, I almost missed it myself (again).
From the Quickref:
"If R/C++ types match, use pointer to x."
Use a non-integer input to your function and see if that works. Take
a look at this example:
src <- '
Rcpp::NumericMatrix r_m(mem);
int nn = r_m.nrow() * r_m.ncol();
// int nn = r_m.size();
// above doesnt work with NumericMatrix, .size() is ambiguous??
for (int ii =0; ii < nn; ii++) {
r_m[ii] = r_m[ii] + r_m[ii];
}
return r_m;
'
require(inline)
require(RcppArmadillo)
myfun = cxxfunction(signature(mem='numeric'), src, plugin='Rcpp')
ll <<- mm <<- matrix((1:10)/10, nrow=2)
llint <<- mmint <<- matrix(1:10, nrow=2)
myfun(mm)
## should be false, since myfun modifies mm directly?
print(all.equal(mm, ll))
print(all.equal(mmint, llint))
hth,
-Christian
--
A man, a plan, a cat, a ham, a yak, a yam, a hat, a canal – Panama!
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