Dear all,
I want to do some computation on a matrix, irrespective of whether it is a
numeric matrix, an integer matrix or a sparse matrix (a dgCMatrix which can be
handled with RcppEigen). For simplicity, I want to compute the sum of the
elements.
To do so I use a template
template <typename TT>
SEXP do_compute( SEXP XX_ ){
const TT X(as<TT>(XX_));
return wrap(X.sum()); // some computation on X...
};
I then dispatch depending on input type with
// [[Rcpp::export]]
SEXP compute ( SEXP XX_ ){
int type = TYPEOF(XX_) ;
Rf_PrintValue(wrap(type));
switch( type ){
case 13 : return do_compute<MapMati>(XX_); // matrix - integer
case 14 : return do_compute<MapMatd>(XX_); // matrix - double
case 25 : return do_compute<MSpMat>(XX_); // dgCMatrix
}
return R_NilValue ;
}
and the numbers 13, 14, 25 are disclosed to by simply printing the type. I know
that for integers and doubles I can do something "nicer":
// [[Rcpp::export]]
SEXP compute2 ( SEXP XX_ ){
int type = TYPEOF(XX_) ;
Rf_PrintValue(wrap(type));
switch( type ){
case INTSXP : return do_compute<MapMati>(XX_); // matrix - integer
case REALSXP : return do_compute<MapMatd>(XX_); // matrix - double
case 25 : return do_compute<MSpMat>(XX_); // dgCMatrix
}
return R_NilValue ;
}
Questions:
Is there a similar keyword for sparse matrices??
If not, is the "code" 25 safe to use in an R-package??
Are there more elegant ways of handling the dispatch ??
The source file is attached. Thanks in advance.
Søren
#include <RcppEigen.h>
//[[Rcpp::depends(RcppEigen)]]
using namespace Rcpp;
typedef Eigen::Map<Eigen::MatrixXd> MapMatd;
typedef Eigen::Map<Eigen::MatrixXi> MapMati;
typedef Eigen::MappedSparseMatrix<double> MSpMat;
// [[Rcpp::export]]
SEXP getType ( SEXP XX_ ){
int type = TYPEOF(XX_) ;
return wrap(type);
}
template <typename TT>
SEXP do_compute( SEXP XX_ ){
const TT X(as<TT>(XX_));
return wrap(X.sum()); // some computation on X...
};
// [[Rcpp::export]]
SEXP compute ( SEXP XX_ ){
int type = TYPEOF(XX_) ;
Rf_PrintValue(wrap(type));
switch( type ){
case 13 : return do_compute<MapMati>(XX_); // matrix - integer
case 14 : return do_compute<MapMatd>(XX_); // matrix - double
case 25 : return do_compute<MSpMat>(XX_); // dgCMatrix
}
return R_NilValue ;
}
// [[Rcpp::export]]
SEXP compute2 ( SEXP XX_ ){
int type = TYPEOF(XX_) ;
Rf_PrintValue(wrap(type));
switch( type ){
case INTSXP : return do_compute<MapMati>(XX_); // matrix - integer
case REALSXP : return do_compute<MapMatd>(XX_); // matrix - double
case 25 : return do_compute<MSpMat>(XX_); // dgCMatrix
}
return R_NilValue ;
}
/*** R
library(Matrix)
m <- matrix(1:9, nrow=3)
M <- as(m, "dgCMatrix")
getType( m ); getType( M ); getType( 1 ); getType( 1L )
compute( m ) # integer
compute( 1*m ) # double
compute( M ) # sparse dgCMatrix
*/
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