B

INSTALLING AND USING PACKAGES

One of the major strengths of R is that

thousands of user-written packages are

available on the Comprehensive R Archive

Network (CRAN) at the R home page,http://

http://www.r-project.org/. Package installation is easy in most

cases, but there are nuances to be aware of for some of

the specialty packages.

This appendix starts with some package basics and then explains how to

load R packages from your hard drive and from the Web.

B.1 Package Basics.............................................................

R uses packages to store groups of related pieces of software. The packages

that are included with the R distribution are visible as subdirectories of your

librarydirectory in your R installation tree, as in/usr/lib/R/library.

NOTE In the R community, the termlibraryis often used in place ofpackage.

Some packages are loaded automatically when you start R, such as the

basesubdirectory. However, in order to save memory and time, R does not

load all available packages automatically.