Appendix B. R Packages

Many of R’s most useful functions do not come preloaded when you start R, but reside in packages that can be installed on top of R. R packages are similar to libraries in C, C++, and Javascript, packages in Python, and gems in Ruby. An R package bundles together useful functions, help files, and data sets. You can use these functions within your own R code once you load the package they live in. Usually the contents of an R package are all related to a single type of task, which the package helps solve. R packages will let you take advantage of R’s most useful features: its large community of package writers (many of whom are active data scientists) and its prewritten routines for handling many common (and exotic) data-science tasks.

Base R

You may hear R users (or me) refer to “base R.” What is base R? It is just the collection of R functions that gets loaded every time you start R. These functions provide the basics of the language, and you don’t have to load a package before you can use them.

Installing Packages

To use an R package, you must first install it on your computer and then load it in your current R session. The easiest way to install an R package is with the install.packages R function. Open R and type the following into the command line:

install.packages("package name")

This will search for the specified package in the collection of packages hosted on the CRAN site. When R finds the package, it will download it into a libraries folder on your computer. ...

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