[Rd] Questions on how to handle R objects in C

Wen Wan wenw at vt.edu
Thu Jun 8 18:50:28 CEST 2006


I have a question on how to handle R objects in C. I have spent a lot of time 
on it but I still can not figure it out.

My situation is as following. I have already had C++ code for a genetic 
algorithm. The genetic algorithm need function evaluations. And the function I 
am going to use includes matrix inverse and other matrix manipulation. As you 
know, doing matrix manipulation is hard by C++ but is much easier by R. What I 
want to do is to use R to call C subroutine (genetic algorithm), but in the C 
code, let R help C do matrix manipulation. So I need use .Call instead of .C. 
I got some information on it from website 
(http://lib.stat.cmu.edu/R/CRAN/doc/manuals/R-exts.pdf), but it is hard to 
read and understand. I also read the introduction to the .C interface to R 
which you told me, but it is not the same situation as what I have.

I have another problem. I don’t know how to put a lot of C functions together 
when we use .C or .Call. This is different from the C code itself. In C code 
itself, we have main() function, list several functions’ definitions outside 
of the main(), before the main(), we need add those functions’ declaration. I 
don’t know how to range those functions if we want to use R to call C.

If all of these questions need take you a lot time to explain, would you 
please give me some examples which you used before. Thank you very much.

Best wishes,


Wen Wan
Department of Statistics
Virginia Polytechnic University
403-D Hutcheson Hall
Blacksburg, VA 24061-0439
Email:         wenw at vt.edu
Phone:        (540)922-2496
Fax:           (540) 231-3863

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