R dummies

Chapter 20Ten Tips on Working with PackagesIn This ChapterFinding packagesInstalling and updating packagesLoading and unloading packagesOne of the very attractive features of R is that it contains a large collection ofthird-party packages (collections of functions in a well-defined format). To get themost out of R, you need to understand where to find additional packages, how todownload and install them, and how to use them.In this chapter, we consolidate some of the things we cover earlier in the bookand give you ten tips on working with packages.Many other software languages have concepts that are similar to Rpackages. Sometimes these are referred to as “libraries.” However, in R, alibrary is the folder on your hard disk (or USB stick, network, DVD, or whateveryou use for permanent storage) where your packages are stored.Poking Around the Nooks and Crannies of CRANThe Comprehensive R Archive Network (CRAN; http://cran.r-project.org) isa network of web servers around the world where you can find the R source code, Rmanuals and documentation, and contributed packages.CRAN isn’t a single website; it’s a collection of web servers, each with anidentical copy of all the information on CRAN. Thus, each web server is called amirror. The idea is that you choose the mirror that is located nearest to where youare, which reduces international or long-distance Internet traffic. You can find a listof CRAN mirrors at http://cran.r-project.org/mirrors.html.