has_devel.install_version(package, version = NULL, repos = getOption("repos"),
type = getOption("pkgType"), ...)install. Otherwise, it looks at the list of
archived source tarballs and tries to install a"http://cran.us.r-project.org". For more details on
supported URL schemes see url.
"source" except on Windows and some OS X
builds: see the section on install.install_bitbucket;
install_github; install_git;
install_svn; install_url;
install; uninstall