1
查看this post後,我試圖用Rcpp
子集矩陣。矩陣RcppGSL的快速子集
隨着RcppArmadillo
:
// [[Rcpp::depends(RcppArmadillo)]]
#include "RcppArmadillo.h"
// [[Rcpp::export]]
arma::mat submatrix(const arma::mat& m1in, int fromin, int toin){
arma::mat s1 = m1in.cols(fromin-1,toin-1);
return(s1);
}
然後submatrix(M, 1, 900)
有點比M[,1:900]
更快。
隨着RcppGSL
:
#include <RcppGSL.h>
#include <gsl/gsl_matrix.h>
// [[Rcpp::export]]
gsl_matrix_const_view submatrix(const RcppGSL::Matrix & X, int k1, int k2, int n1, int n2) {
return gsl_matrix_const_submatrix(X, k1, k2, n1, n2);
}
這裏submatrix(M, 0, 0, 1000, 900)
比M[,1:900]
慢:
> microbenchmark(M[,1:900], submatrix(M, 0, 0, 1000, 900))
Unit: milliseconds
expr min lq mean median uq max neval
M[, 1:900] 8.035749 10.20265 13.25657 11.75554 14.27586 117.2533 100
submatrix(M, 0, 0, 1000, 900) 16.597605 19.55858 23.04454 21.52959 23.98431 141.6158 100
是否有子集RcppGSL
矩陣更快的方法?