在C ++中使用稀疏矩阵的RCPP

Question

Overwhelmed with starting with RCCP. How would I be able to use (index,read and assign values) a sparse matrix as defined in the code the same way as I can do with the 'standard' matrix?

library('Matrix')
library(Rcpp)
library(inline)

r <- matrix(seq(1,9,1),ncol=3,nrow=3)
i <- Matrix(0, nrow = nrow(r) * ncol(r), ncol = nrow(r)*ncol(r), sparse=TRUE)
fx <- cxxfunction( signature( x_ = "matrix" ,y_="dsCMatrix"), '
    NumericMatrix x(x_) ;
    int nr = x.nrow(), nc = x.ncol() ;
    for (int i = 0; i < nr; i++) {
             for (int j = 1; j < nc; j++) {
             x(i,j) = 1;
         }
    }
    return wrap( x ) ;
', plugin = "Rcpp" )

fx( r,i)

Answer 1

Your best bet may be

• the posts about sparse matrices at the Rcpp Gallery , and
• the rcpp-devel mailing list.