Hi Jouni,
On 22 September 2016 at 20:38, Helske, Jouni wrote:
| yes I am familiar with new style (thank you for that, it makes things much
prettier), but I still have to (or do I?...) use the as<>() when I am picking
the pieces out of Rcpp::List
(https://github.com/helske/bssm/blob/master/src/gssm.cpp):
|
| ....
| gssm::gssm(const List model, unsigned int seed) :
| y(as<arma::vec>(model["y"])), Z(as<arma::mat>(model["Z"])),
| H(as<arma::vec>(model["H"])), T(as<arma::cube>(model["T"])), ...
|
| I don't want to modify objects on the R side, so I had to use clone for the
List model. I was just wondering why the behaviour is different for cube (tries
to avoid a copy) than for vec/mat when using as<>() (always? forces a copy).
I see. That is a potentially more hairy question because now we at the
'conversion from SEXP' (as a member of Rcpp::List) level.
The nice thing is that we have an existence proof in what Rcpp Attributes
does, so you could always re-run snippets like the one I have below with
verbose=TRUE (and maybe rebuild=TRUE). In this case we see
Rcpp::traits::input_parameter< arma::cube& >::type x(xSEXP);
test2(x);
The differences between vec and mat on the one hand and cube on the other are
probably accidental. If you have time to chase this and clean it up a PR
would be great.
Dirk
| Jouni
|
| ________________________________________
| Lähettäjä: Dirk Eddelbuettel [e...@debian.org]
| Lähetetty: 22. syyskuuta 2016 23:09
| Vastaanottaja: Dirk Eddelbuettel
| Kopio: Helske, Jouni; rcpp-devel@lists.r-forge.r-project.org
| Aihe: Re: [Rcpp-devel] Initializing Armadillo vec/cube from NumericVector
using as conversion
|
| Oh, and it should work the same for cube types:
|
| R> cppFunction("void test2(arma::cube & x) { x(0,0,0) = 0.5; }",
| R> depends="RcppArmadillo")
| R> v <- array(sqrt(1:8), c(2, 2, 2))
| R> v
| , , 1
|
| [,1] [,2]
| [1,] 1.00000 1.73205
| [2,] 1.41421 2.00000
|
| , , 2
|
| [,1] [,2]
| [1,] 2.23607 2.64575
| [2,] 2.44949 2.82843
|
| R> test2(v)
| R> v
| , , 1
|
| [,1] [,2]
| [1,] 0.50000 1.73205
| [2,] 1.41421 2.00000
|
| , , 2
|
| [,1] [,2]
| [1,] 2.23607 2.64575
| [2,] 2.44949 2.82843
|
| R>
|
| Proxy object that still connected to the outside object, unless a cast is
| needed (int <-> double), or a copy is enforced (clone(), possibly via as<>()).
|
| Dirk
|
| --
| http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
--
http://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org
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