Hi Martin, On 21 August 2012 at 15:38, Martin Oberhuber wrote: | Dear Rcpp Users, | | I would like to concatenate two NumericVectors. For instance: | | ... | NumericVector a( some_STL_vector ) ; | NumericVector b( some_STL_vector ) ; | | ... // using Rcpp sugar on a and b | | a.insert( a.end(), b.begin(), b.end() ); | | ... // using Rcpp sugar on a | | | | This would work fine if a and be were of type std::vector<double>. However, | NumericVector does not seem to have an insert function which supports the | structure above and therefore this isn't working.
Rcpp objects are proxy objects for R objects. And R objects do not grow gracefully. We do offer STL-alike functions like push_back() but also warn that they will not be high-performance as _every_ addition will create a full copy of the full vector. That is the price of being close to R objects. | Any ideas on how I could concatenate the two vectors using a different | methodology? The reason I would like to use NumericVectors here is because I am One easy way: Compute n = n_a + n_b, insert a new vector of size n, insert a, insert b -- and wrap all that in a little helper function. More elegant solutions are welcome as patches :) | using Rcpp sugar on a and b and the resulting concatenated vector and I would | like to avoid converting them back and forth between std::vector and | NumericVector. For those reasons I have at times switched to using Armadillo vectors as containers. Hope this helps, Dirk -- Dirk Eddelbuettel | e...@debian.org | http://dirk.eddelbuettel.com _______________________________________________ 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
