[Rd] array indexes in C

Benjamin Tyner btyner at stat.purdue.edu
Sun Nov 19 15:55:17 CET 2006


You could write convenience functions, but I have used the C99 mechanism 
for variable length arrays with no problems calling from R. One thing 
you have to keep in mind though is that (as far as I know) the 
dimensions must be passed before the array reference. So for example,

r <- .C("foo",
              x = double(ni * nj),

with your function defined as

void foo(int *ni, int *nj, double x[*ni][*nj])

Then in C you can access elements of x via x[3][4], for example.


More information about the R-devel mailing list