Desktop Survival Guide
by Graham Williams
Much of the usefulness of R comes from functionality implemented in various packages. R provides an extensive collection of packages available from http://www.r-project.orgCRAN. Packages are installed into your own libraries which are directories containing collections of packages. The library function requests R to find a package in some library and load that package. The require function can be used in packages and functions to also load a library, but only give a warning and return FALSE if the package can not be found.