14 Packages

Learning Goals

After this lesson, you should be able to:

Install packages from CRAN
Get a list of installed packages
Load packages you’ve installed
Get a list of loaded packages

A package is a collection of functions for use in R. Packages usually include documentation, and can also contain examples, vignettes, and data sets. Most packages are developed by members of the R community, so quality varies. There are also a few packages that are built into R but provide extra features. We’ll use packages in many of the following chapters, so we’re learning about them now.

The Comprehensive R Archive Network, or CRAN, is the main place people publish packages. As of writing, there were 23,094 packages posted to CRAN. This number has been steadily increasing as R has grown in popularity.

Packages span a wide variety of topics and disciplines. There are packages related to statistics, social sciences, geography, genetics, physics, biology, pharmacology, economics, agriculture, and more. The best way to find packages is to search online, but the CRAN website also provides “task views” if you want to browse popular packages related to a specific discipline.

14.1 Installing Packages

The install.packages function installs one or more packages from CRAN. Its first argument is a name or vector of names of packages to install.

When you run install.packages, R will ask you to choose which mirror to download the package from. A mirror is a web server that has the same set of files as some other server. Mirrors are used to make downloads faster and to provide redundancy so that if a server stops working, files are still available somewhere else. CRAN has dozens of mirrors; you should choose one that’s geographically nearby, since that usually produces the best download speeds. If you aren’t sure which mirror to choose, you can use the 0-Cloud mirror, which attempts to automatically choose a mirror near you.

As an example, here’s the code to install the remotes package:

install.packages("remotes")

If you run the code above, you’ll be asked to select a mirror, and then see output that looks something like this:

--- Please select a CRAN mirror for use in this session ---
trying URL 'https://cloud.r-project.org/src/contrib/remotes_2.5.0.tar.gz'
Content type 'application/x-gzip' length 168405 bytes (164 KB)
==================================================
downloaded 164 KB

* installing *source* package ‘remotes’ ...
** package ‘remotes’ successfully unpacked and MD5 sums checked
** using staged installation
** R
** inst
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
** building package indices
** installing vignettes
** testing if installed package can be loaded from temporary location
** testing if installed package can be loaded from final location
** testing if installed package keeps a record of temporary installation path
* DONE (remotes)

The downloaded source packages are in
        ‘/tmp/Rtmp8t6iGa/downloaded_packages’

R goes through a variety of steps to install a package, even installing other packages that the package depends on. You can tell that a package installation succeeded by the final line DONE. When a package installation fails, R prints an error message explaining the problem instead.

Important

Once a package is installed, it stays on your computer until you remove it or remove R. This means you only need to install each package once!

Most packages are periodically updated. You can update specific packages to the latest versions by reinstalling them with install.packages. Alternatively, you can update all of the R packages you’ve installed at once by calling the update.packages function. Beware that this may take a long time if you have a lot of packages installed.

The function to remove packages is remove.packages. Like install.packages, this function’s first argument is the packages to remove, as a character vector.

If you want to see which packages are installed, you can use the installed.packages function. It does not require any arguments. It returns a matrix with one row for each package and columns that contain a variety of information. Here’s an example:

packages = installed.packages()
# Just print the version numbers for 10 packages.
packages[1:10, "Version"]

   askpass assertthat       base  base64enc        bit      bit64       boot 
   "1.2.1"    "0.2.1"    "4.5.2"    "0.1-3"    "4.6.0"  "4.6.0-1"   "1.3-32" 
     bslib     cachem cellranger 
   "0.9.0"    "1.1.0"    "1.1.0"

You’ll see a different set of packages, since you have a different computer.

Note

Not all R packages are published to CRAN. GitHub is another popular place to publish R packages, especially ones that are experimental or still in development. Unlike CRAN, GitHub is a general-purpose website for publishing code written in any programming language, so it contains much more than just R packages and is not specifically R-focused.

The remotes package that we just installed provides functions to install packages from GitHub. It is generally better to install packages from CRAN when they are available there, since the versions on CRAN tend to be more stable and intended for a wide audience. However, if you want to install a package from GitHub, you can learn more about the remotes package by reading its online documentation.

14.2 Loading Packages

Before you can use the functions (or other resources) in an installed package, you must load the package with the library function. R doesn’t load packages automatically because each package you load uses memory and may conflict with other packages. Thus you should only load the packages you need for whatever it is that you want to do. When you restart R, the loaded packages are cleared and you must again load any packages you want to use.

Let’s load the remotes package we installed earlier:

library("remotes")

The library function works with or without quotes around the package name, so you may also see people write things like library(remotes). We recommend using quotes to make it unambiguous that you are not referring to a variable.

A handful of packages print out a message when loaded, but the vast majority do not. Thus you can assume the call to library was successful if nothing is printed. If something goes wrong while loading a package, R will print out an error message explaining the problem.

Occasionally, you might need to check the names and versions of the packages loaded in your R session. For instance, if you go to another R programmer for help, they’ll probably ask. You can make R print out information about the session, including loaded packages, with the sessionInfo function:

sessionInfo()

R version 4.5.2 (2025-10-31)
Platform: x86_64-conda-linux-gnu
Running under: Arch Linux

Matrix products: default
BLAS/LAPACK: /home/nick/mill/datalab/teaching/adventures_in_data_science/.pixi/envs/default/lib/libopenblasp-r0.3.30.so;  LAPACK version 3.12.0

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C
 [3] LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8
 [7] LC_PAPER=en_US.UTF-8       LC_NAME=C
 [9] LC_ADDRESS=C               LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C

time zone: US/Pacific
tzcode source: system (glibc)

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] remotes_2.5.0

loaded via a namespace (and not attached):
[1] compiler_4.5.2 tools_4.5.2

The output from sessionInfo will be different on your computer, depending on your computer hardware, operating system, default language, time zone, version of R, and loaded packages.