Sergej,
Please consider: - there are nearly 20k CRAN packages - all of them are mirrored at https://github.com/cran so you can browse - pick any one 'heavy' package you like, Seurat is a good example; there are other examples in geospatial or bioinformatics etc - you can browse _and search_ these to your hearts content Here is an example of mine. In RcppArmadillo, years ago we (thanks to fine Google Summer of Code work by Binxiang Ni) added extended support for sparse matrices pass-through / conversione from R to C++ / Armadillo and back. That is clearly an optional feature as most uses of (Rcpp)Armadillo use dense matrices. So all code and test code is _conditional_. File DESCRIPTION has Suggests: [...], Matrix (>= 1.3.0), [...], reticulate, slam mostly for tests. I.e. We have very little R code: in one single file R/SciPy2R.R we switched to doing this via reticulate and opee the function with if (!requireNamespace("reticulate", quietly=TRUE)) { stop("You must install the 'reticulate' package (and have SciPy).", call.=FALSE) } after an actual deprecation warning (as there was scipy converter once). Similarly, the testsuites in inst/tinytests/* have several if (!requireNamespace("Matrix", quietly=TRUE)) exit_file("No Matrix package") as well as if (!requireNamespace("reticulate", quietly=TRUE)) exit_file("Package reticulate missing") if (!packageVersion("reticulate") >= package_version("1.14")) exit_file("SciPy not needed on newer reticulate") and tests for slam (another sparse matrix package besides the functionality in Matrix). Hopefully this brief snapshot gives you an idea. There are (likely!!) thousandss of examples you can browse, and I am sure you will find something. If you have further (concrete) questions please do not hesitate to use the resource of this list. Cheers (or I should say "mit Braunschweiger Gruessen nach Hannover), Dirk -- dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel