[Rcpp-devel] Non-contiguous submatrix
Thanks Dirk! That looks interesting! I will check which solution performs better in my application! Best Simon
On Aug 26, 2013, at 1:24 PM, Dirk Eddelbuettel <edd at debian.org> wrote:
On 26 August 2013 at 12:19, Simon Zehnder wrote: | Dear Rcpp::Users and Rcpp::Devels, | | I am right now working on a relabeling algorithm where I have a function | taking a permutation matrix of all permutations of the labels. Inside the | function the values should be permuted in respect to a row of this | matrix. In R I would use the following commands: | | values <- matrix(rnorm(4), ncol = 2, nrow = 2, byrow = TRUE) | perm <- as.matrix(expand.grid(seq(1, 2), seq(1, 2))) | index <- perm[which(perm[, 1] != perm[, 2]),] | values[, index[, 1]] | values[, index[, 2]] | | I found this thread on stackoverflow: | http://stackoverflow.com/questions/8435169/selecting-a-non-contiguous-submatrix-in-rcpp. Are | there any proceedings for non-contiguous submatrices in Rcpp? Not in Rcpp -- but Armadillo has it and this example on the Rcpp Gallery uses it along with RcppArmadillo: http://gallery.rcpp.org/articles/armadillo-subsetting/ Dirk -- Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com