C code and R

A couple of questions on calling C programs
from R functions:

1. Is there any other guide on this matter in addition to
Writing R Extensions ?

Not specifically on R. You may find the book "S Programming" by Venables &
Ripley useful.

2. Writing R Extensions starts dealing with C programs
assuming that those have already been compiled:
"Interface functions .C and .Fortran

These two functions provide a standard interface to compiled code that has
been linked into R,... "

Are there any constraints that should be considered
at compiling a function that is intended to be called by R?

Not really, if .C is being used to call it. It is a good idea to use R's
facilities if you want to print to the screen from C code, and it may well
help to use R's memory management (eg Calloc or R_alloc) rather than
managing memory yourself, but these are optional.

While you need to learn more initially it is often more effective to use
the .Call() interface unless you need portability between S and R (and
sometimes even then).

Splus (unix v 3.x) used to have an script
(Splus COMPILE) to make sure that the compilation was done
with the proper flags. Is there an equivalent R COMPILE
script?

Section 4.4 of "Writing R Extensions" describes how you do this.

	-thomas

Thomas Lumley			Asst. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle

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