Error passing `arma :: cube`argument to function using RcppArmadillo
I am getting the following error when I try to compile with a package sourceCpp
from Rcpp
:
`my path to R/.../Rcpp/internal/Exporter.h`
no matching function for call to 'arma::Cube<double>::Cube(SEXPREC*&)'
The object cube
is the equivalent armadillo
array
in R
.
EDIT . Note that the problem is that the function cannot accept an object arma::cube
as an argument. If we change arma::cube B
to arma::mat B
, it works:
#include <RcppArmadillo.h>
// [[Rcpp::depends(RcppArmadillo)]]
using namespace arma;
// [[Rcpp::export]]
arma::cube ssmooth(arma::mat A,
arma::cube B) {
int ns = A.n_rows;
int nk = A.n_cols;
int np = B.n_rows;
arma::mat C = zeros<mat>(nk, ns);
arma::cube D = zeros<cube>(nk, nk, ns);
return D;
}
Any hint would be appreciated.
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Basic example works:
R> cppFunction("arma::cube getCube(int n) { arma::cube a(n,n,n);\
a.zeros(); return a; }", depends="RcppArmadillo")
R> getCube(2)
, , 1
[,1] [,2]
[1,] 0 0
[2,] 0 0
, , 2
[,1] [,2]
[1,] 0 0
[2,] 0 0
R>
so either you are doing something wrong or your installation is disabled.
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I had the same problem. The problem seems to be related to the combination of "Rcpp :: export" and the cube as an argument to the exported function. I'm guessing that the sexp to cube converter hasn't been implemented yet (no pun intended ;-)). (Or we are both missing something ...).
A workaround when you want to have an arma :: cube argument in the Rcpp :: export function: first get it as a NumericVector and just create the cube after that ...
#include <RcppArmadillo.h>
// [[Rcpp::depends(RcppArmadillo)]]
using namespace arma;
// [[Rcpp::export]]
arma::cube ssmooth(arma::mat A,
NumericVector B_) {
IntegerVector dimB=B_.attr("dim");
arma::cube B(B_.begin(), dimB[0], dimB[1], dimB[2]);
//(rest of your code unchanged...)
int ns = A.n_rows;
int nk = A.n_cols;
int np = B.n_rows;
arma::mat C = zeros<mat>(nk, ns);
arma::cube D = zeros<cube>(nk, nk, ns);
return D;
}
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I think your code is failing because it is implicitly trying to do the casting like this:
#include<RcppArmadillo.h>
using namespace Rcpp;
using namespace arma;
// [[Rcpp::depends(RcppArmadillo)]]
// [[Rcpp::export]]
cube return_thing(SEXP thing1){
cube thing2 = as<cube>(thing1);
return thing2;
}
/***R
thing <- 1:8
dim(thing) <- c(2, 2, 2)
return_thing(thing)
*/
which doesn't work, whereas it works for matrices:
#include<RcppArmadillo.h>
using namespace Rcpp;
using namespace arma;
// [[Rcpp::depends(RcppArmadillo)]]
//[[Rcpp::export]]
mat return_thing(SEXP thing1){
mat thing2 = as<mat>(thing1);
return thing2;
}
/***R
thing <- 1:4
dim(thing) <- c(2, 2)
return_thing(thing)
*/
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