Hi Jon,
On 12 October 2016 at 14:20, Jonathan Fintzi wrote:
| Thanks for the quick response. In the broader project, the vector being copied
| from is an Rcpp::NumericVector that contatenates vectorized versions of a
| number of other objects that are integrated numerically using the boost odeint
| solvers. I couldn't quite get the numerical integrators to play nice with
| Armadillo objects, and in using std::copy I was trying to avoid converting the
| vector 'v' to an arma::vec since I would have to convert it back for further
| integration. Perhaps this was a mistake?
Yes -- the transformation in as essentially costless. We have some
benchmarking that show that.
| Still, I don't quite understand why armadillo row pointers don't work which
| armadillo column pointers are fine.
Now you phrase your question as "arma-only" (which makes sense) but that
is not what your code does, is it?
I see that you are having an issue mixing things. So I suggest an easy
simplification. You are of course free to ignore that -- but you may then
have to provide another layer as the compiler so far appears to be unhappy.
Dirk
| Thanks,
| Jon
|
| On Wed, Oct 12, 2016 at 2:10 PM, Dirk Eddelbuettel <e...@debian.org> wrote:
|
|
| On 12 October 2016 at 13:43, Jonathan Fintzi wrote:
| | Hello,
| |
| | I am trying to use the std::copy() function to copy elements from an
| | Rcpp::NumericVector into rows of armadillo matrices. A simplified
version
| of my
| | code is as follows:
| |
| | cppFunction('void copyinto(Rcpp::NumericVector& v, arma::mat& d1,
| arma::mat&
| | d2) {
| | std::copy(v.begin(), v.begin() + 3, d1.begin_row(0));
| | std::copy(v.begin() + 3, v.end(), d2.begin_row(0));
| | }', depends = "RcppArmadillo")
|
| You should not need to mix an _Rcpp_ vector with an _Armadillo_ matrix
| using
| std::copy. Check the decent Armadillo docs -- all the subsetting and
| slicing
| can be done with Armadillo. And that is what I would do.
|
| But maybe I didn't quite understand what you are really after.
|
| Dirk
|
| | v <- runif(6)
| | d1 <- matrix(0.0, 3,3)
| | d2 <- matrix(0.0, 3,3)
| |
| | copyinto(v, d1, d2)
| |
| | However, when I attempt to compile the code, I receive a list of
| compilation
| | errors including "no type named 'XXXXXX' in 'class arma::Mat<double>
| | row_iterator", where XXXXXX is iterator_category, value_type,
| difference_type,
| | pointer, and reference.
| |
| | If I change the iterators to column iterators (e.g. d1.begin_col(0))
| everything
| | compiles and works just fine. I feel that I must be missing something
| quite
| | basic here, but in searching around I haven't been able to identify my
| mistake.
| |
| | Thank you for your help!
| | Jon
| | _______________________________________________
| | Rcpp-devel mailing list
| | Rcpp-devel@lists.r-forge.r-project.org
| | https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
|
| --
| http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
|
|
--
http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
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