[Rcpp-devel] convert to unsigned char* variable
Dirk Eddelbuettel
edd at debian.org
Mon Oct 20 21:54:01 CEST 2014
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,
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
|
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--
http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
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