[Rcpp-devel] convert to unsigned char* variable

[Romain Francois]

> Le 20 oct. 2014 à 21:54, Dirk Eddelbuettel <edd at debian.org> a écrit :
> 
> 
> Hi Gustaf,
> 
> On 20 October 2014 at 15:17, Gustaf Granath wrote:
> | Im trying to use some C++ functions in R. However, these functions are 
> | build around unsigned char* variables (1D array). I have for example a 
> | large matrix in R that represents black (e.g. 1-bit image, 0 and 1s). I 
> | cant find a solution to convert a character vector into unsigned char* 
> | within Rcpp. Im new to Rcpp and C++ so I might have missed something 
> 
> Rcpp builds a bridge between R and C++, and supports (in C++) the types that
> R supports.  Eg you won't find 'float' but only 'double' as that is what R
> does. 
> 
> Here you will get character vectors easily. If they must be unsigned char,
> you will probably have to cast them at the C++ level.
> 
> | obvious here. Please direct me to resources on this topic (google did 
> | not help much).
> | 
> | A start:
> | 
> | SEXP test(SEXP cM){
> |    CharacterVector Vc(cM);
> |    int n = Vr.size();
> |    RawVector x(n); //is this the same as unsigned char* ?
> 
> No, RawVector is for R 'raw' types -- see help("raw") in R,

Guess what raw is !!!

> demangle( "RawVector::stored_type" )
[1] "unsigned char"


> Dirk
> 
> |                              //I tried to fill it with char*(Mr) but I 
> | didnt succeed
> | }
> | 
> | Thanks,
> | 
> | Gustaf
> | 
> | -- 
> | Gustaf Granath (PhD)
> | Post doc
> | McMaster University
> | School of Geography & Earth Sciences
> | 
> | _______________________________________________
> | Rcpp-devel mailing list
> | Rcpp-devel at lists.r-forge.r-project.org
> | https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
> 
> -- 
> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
> _______________________________________________
> Rcpp-devel mailing list
> Rcpp-devel at lists.r-forge.r-project.org
> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel