I would like to, within my own compiled C++ code, check to see if a library package is loaded in R (if not, load it), call a function from that library and get the results back to in my C++ code.
Could someone point me in the right direction? There seems to be a plethora of info on R and different ways of calling R from C++ and vis versa, but I have not come across exactly what I am wanting to do.
Thanks.
2 Answers
Dirk's probably right that RInside makes life easier. But for the die-hards... The essence comes from Writing R Extensions sections 8.1 and 8.2, and from the examples distributed with R. The material below covers constructing and evaluating the call; dealing with the return value is a different (and in some sense easier) topic.
Setup
Let's suppose a Linux / Mac platform. The first thing is that R must have been compiled to allow linking, either to a shared or static R library. I work with an svn copy of R's source, in the directory ~/src/R-devel. I switch to some other directory, call it ~/bin/R-devel, and then
~/src/R-devel/configure --enable-R-shlib
make -j
this generates ~/bin/R-devel/lib/libR.so; perhaps whatever distribution you're using already has this? The -j flag runs make in parallel, which greatly speeds the build.
Examples for embedding are in ~/src/R-devel/tests/Embedding, and they can be made with cd ~/bin/R-devel/tests/Embedding && make. Obviously, the source code for these examples is extremely instructive.
