My RStudio code snippets, which can be installed using the snippr package as follows:
Note that a .snippets file for a language may not yet exist. If it does not exist, go to Preferences->Code->Edit Snippets in RStudio, make a trivial change to the language of choice (for example, a new empty line), and click Save. This will create the language file in ~/.R/snippets/.snippets with defaults included.
devtools::install_github("dgrtwo/snippr")
library(snippr)
snippets_install_github("grahamrp/snippets")