On 21 January 2014 at 22:02, Søren Højsgaard wrote:
| I have made the following primitive "concatenate" function, because I
couldn't find one in Rcpp:
|
| template <const int RTYPE>
| Vector<RTYPE> do_conc_(Vector<RTYPE> x, Vector<RTYPE> y){
| int nx=x.size(), n=x.size()+y.size(),i,j;
| Vector<RTYPE> out=no_init(n);
| for (i=0; i<nx; ++i){ out[ i ] = x[ i ];}
| for (j=i, i=0; j<n; ++j, ++i){ out[ j ] = y[i] ;}
| return out;
| }
|
| // [[Rcpp::export]]
| SEXP conc( SEXP& XX_, SEXP& YY_){
| int type = TYPEOF(XX_) ;
| switch( type ){
| case INTSXP : return do_conc_<INTSXP> ( XX_, YY_ ) ;
| case REALSXP : return do_conc_<REALSXP>( XX_, YY_ ) ;
| case STRSXP : return do_conc_<STRSXP> ( XX_, YY_ ) ;
| case VECSXP : return do_conc_<VECSXP> ( XX_, YY_ ) ;
| }
| return R_NilValue ;
| }
|
| As you can see it assumes that the two inputs XX_ and YY_ are of the same
type, and it fails to copy names to the output. If I have missed any such
functionality in Rcpp then I would be happy to know...
My instinct would be to use RcppArmadillo vectors:
R> cppFunction("arma::colvec conc(const arma::colvec & x, const arma::colvec &
y) { return arma::join_cols(x, y); }", depends="RcppArmadillo")
R> conc(1:3, 11:13)
[,1]
[1,] 1
[2,] 2
[3,] 3
[4,] 11
[5,] 12
[6,] 13
R>
For more _generic_ solutions, the STL offers a lot.
Dirk
--
Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com
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