Rcpp: Seamless R and C Integration
Synopsis
The Rcpp package help to integrate R and C via R functions and a (header-only) C library.
All underlying R types and objects, i.e., everything a
SEXP represents internally in R, are matched to
corresponding C objects. This covers anything from vectors, matrices
or lists to environments, functions and more. Each SEXP
variant is automatically mapped to a dedicated C class. For example,
numeric vectors are represented as instances of the
Rcpp::NumericVector class, environments are represented as
instances of Rcpp::Environment, functions are represented
as Rcpp::Function, etc … The Rcpp-introduction
vignette (now published as a TAS
paper; an earlier
introduction was also published as a JSS paper) provides a good
entry point to Rcpp as do the Rcpp
website, the Rcpp page and
the Rcpp Gallery. Full
documentation is provided by the Rcpp book.
Other highlights:
The conversion from C to R and back is driven by the templates
Rcpp::wrapandRcpp::aswhich are highly flexible and extensible, as documented in the Rcpp-extending vignette.Rcpp also provides Rcpp modules, a framework that allows exposing C functions and classes to the R level. The Rcpp-modules vignette details the current set of features of Rcpp-modules.
Rcpp includes a concept called Rcpp sugar that brings many R functions into C . Sugar takes advantage of lazy evaluation and expression templates to achieve great performance while exposing a syntax that is much nicer to use than the equivalent low-level loop code. The Rcpp-sugar gives an overview of the feature.
Rcpp attributes provide a high-level syntax for declaring C functions as callable from R and automatically generating the code required to invoke them. Attributes are intended to facilitate both interactive use of C within R sessions as well as to support R package development. Attributes are built on top of Rcpp modules and their implementation is based on previous work in the inline package. See the Rcpp-atttributes vignettes for more details.
Documentation
The package ships with nine pdf vignettes, including a recent introduction to Rcpp now published as a paper in TAS (and as a preprint in PeerJ). Also available is an earlier introduction which was published as a JSS paper)
Among the other vignettes are the Rcpp FAQ and the introduction to Rcpp Attributes. Additional documentation is available via the Rcpp book by Eddelbuettel (2013, Springer); see ‘citation(“Rcpp”)’ for details.
Examples
The Rcpp Gallery showcases over one hundred fully documented and working examples. The package RcppExamples contains a few basic examples covering the core data types.
A number of examples are included, as are well over one thousand unit tests which provide additional usage examples.
An earlier version of Rcpp, containing what we now call the ‘classic Rcpp API’ was written during 2005 and 2006 by Dominick Samperi. This code has been factored out of Rcpp into the package RcppClassic, and it is still available for code relying on the older interface. New development should always use this Rcpp package instead.
Other usage examples are provided by packages using Rcpp. As of June 2020, there are 1990 CRAN packages using Rcpp, a further 203 BioConductor packages in its current release as well as an unknown number of GitHub, Bitbucket, R-Forge, … repositories using Rcpp. All these packages provide usage examples for Rcpp.
Installation
Released and tested versions of Rcpp are available via the CRAN network, and can be installed from within R via
install.packages("Rcpp")To install from source, ensure you have a complete package development environment for R as discussed in the relevant documentation; also see questions 1.2 and 1.3 in the Rcpp-FAQ.
Support
The best place for questions is the Rcpp-devel mailing list hosted at R-forge. Note that in order to keep spam down, you must be a subscriber in order to post. One can also consult the list archives to see if your question has been asked before.
The issue tickets at the GitHub repo are the primary bug reporting interface. As with the other web resources, previous issues can be searched as well.
Authors
Dirk Eddelbuettel, Romain Francois, JJ Allaire, Kevin Ushey, Qiang Kou, Nathan Russell, Doug Bates, and John Chambers
License
GPL (>= 2)