Using a external c library in Rcpp

Question

I want to use a c function "rpg_hybrid" that correspond to R library BayesLogit rpg (http://www.inside-r.org/packages/cran/BayesLogit/docs/rpg) in my Rcpp code. I have include LogitWrapper.h and also the library BayesLogit.so to linking stage. GCC still cannot find the rpg_hybrid.

Answer 1

Although it seems like you've solved your problem, I'll provide an answer in the context of developing an R package that you might want to e.g. release to CRAN.

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Basically, the authors of BayesLogit need to explicitly make such routines available for other package authors. This is described in section 5.4.2 of R-exts. From what I can see from the source code, this has not been done, so you will be unable to call the native C/C++ code in that package in a portable, and hence CRAN-acceptable, way.

Your options are:

1. Contact the package authors and ask if they can make this routine available,
2. Copy the source to your own package and give attribution; if you do this, make sure the licence you use is compatible with theirs.

As an aside, Rcpp also has facilities for making source code available in a header only way. The package authors might be convinced to make some routines available by using Rcpp Attributes, as it provides a simple mechanism for allowing other authors to use C++ code in a package; see section 3.5.

Answer 2

A student in my class pointed me to your query. Although I haven't had time to do the things Kevin/Dirk suggested, I have posted a more user-friendly C++ API to my Github page. See https://github.com/jgscott/helloPG

This comes in the form of a R package skeleton which can easily be modified. I hope this will be a workable standby in the interim, until we can modify BayesLogit appropriately.

-James