[R] Calling C code from R...wrapping C structures

[Ramon Diaz-Uriarte]

Dear Nathan,

How is you C function "test" defined? What type of argument is it
expecting? The mappings between R and C type of arguments you can pass
is explained in:

http://cran.r-project.org/doc/manuals/R-exts.html#Interface-functions-_002eC-and-_002eFortran

which also provides some examples. If you want to pass a list, you'll
probably have to use .Call, not .C.

HTH,

R.



On Tue, May 13, 2008 at 1:51 PM, Nathan Harmston
<iwanttobeabadger at googlemail.com> wrote:
> Hi everyone,
>
>  I am currently trying to call some C code from R, specifically calling a
>  function which populates a C struct.
>
>  typedef struct{
>    // contents
>  } Model;
>
>  void test(Model *m){
>    // fill the struct with crap
>  }
>
>  I compile the C code into a shared library, which loads into R properly. My
>  simple test functions work (i.e adding numbers etc)
>  setModel <- function(){
>    model<-vector("list", 6)
>    name(model) <- c( SET THE NAMES OF THE MODEL HERE )
>    model
>  }
>  t <- setModel()
>  testcode <- function(setModel){
>
>
>  dyn.load("Simulation.so")
>
>  foo <- .C("test", Model=setModel)
>  foo
>  }
>
>  testcode(t)
>
>  However I get segfaults whenever I try to access any of the variables
>  contained in Model. So my question is: am I doing something wrong here? Is
>  list the right data type to wrap a structure in? I cant see any
>  documentation about wrapping structs in R.
>
>  Also when I pass strings to C from R they dont seem to be passed at all? Is
>  this a problem with R or a problem with me and if so how do I fix it?
>
>
>
>  Many Thanks in advance,
>
>  Nathan
>
>         [[alternative HTML version deleted]]
>
>  ______________________________________________
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>  PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>  and provide commented, minimal, self-contained, reproducible code.
>



-- 
Ramon Diaz-Uriarte
Statistical Computing Team
Structural Biology and Biocomputing Programme
Spanish National Cancer Centre (CNIO)
http://ligarto.org/rdiaz