[Rcpp-devel] Selecting rows and columns of matrices

| Hi all,
| 
| I've copied the following from a portion of the "Using matrices" section of the
| Rcpp Quick Reference guide. ?I get a compilation error that I'm having trouble
| decoding. ?Commenting out the third line allows it to compile, so it must be
| something I've done wrong with the column selector, but I don't see it. ?
| 
| Thanks in advance,
| Chris
| 
| PS. My?g++ version is 4.5.2, in case that helps.
| 
| src <- '
| NumericMatrix xx(4, 5);
| std::fill(xx.begin(), xx.end(), 8);
| NumericMatrix::Column zzcol = xx( _, 1);
| return(wrap(1));
| ?'
| fun <- ?cxxfunction(signature(x="numeric"), body = src, plugin="Rcpp")
| 
| file3011595e.cpp:35:39: error: invalid conversion from ?SEXPREC*? to
| ?int?
| file3011595e.cpp:35:39: error: ? initializing argument 1 of ?Rcpp::Matrix
| <RTYPE>::Proxy Rcpp::Matrix<RTYPE>::operator()(int, int) [with int RTYPE = 14,
| Rcpp::Matrix<RTYPE>::Proxy = double&]?
| file3011595e.cpp:35:39: error: conversion from ?Rcpp::traits::storage_type
| <14>::type? to non-scalar type ?Rcpp::Matrix<14>::Column? requested
| make: *** [file3011595e.o] Error 1

Works for me:

R> src <- '
+ NumericMatrix xx(4, 5);
+ std::fill(xx.begin(), xx.end(), 8);
+ NumericMatrix::Column zzcol = xx( _, 1);
+ return(wrap(1));
+ '
R> fun <- cxxfunction(signature(x="numeric"), body = src, plugin="Rcpp")
R> fun(4.44)
[1] 1
R> 

Are you by chance using an ancient Rcpp version?

Dirk

Gauss once played himself in a zero-sum game and won $50.
                      -- #11 at http://www.gaussfacts.com