R packages

In the previous sections we have used ‘built in’ R functions such as mean, max and min.

R packages contain additional functions, written and developed by the R community. These packages can contain data sets and functions to perform specialised analysis or graphics.

To download an R package, click on Packages in the Files / Plots / Packages / Help panel, then click on Install package(s). The default option will be to download packages from ‘Repository (CRAN)’, this is where many R packages are uploaded to. In the ‘Packages’ box you can type the name of the package you want to download.

Try downloading the package {RColorBrewer} by typing the package name into the ‘Packages’ box and clicking ‘Install’.

After downloading an R package it will be listed under Packages in the Files / Plots / Packages / Help panel. To use the functions in a package, we must load the R package using library(packagename).

Type library(RColorBrewer) into your R script and run the line. The package will now be loaded and you can use the functions the package contains. .

Exercise

A colleague has sent you some code to make a map of Brazil, but when you run their code you see that you don’t have the required package installed.

map("world", "Brazil") # Map of Brazil
Error in map("world", "Brazil"): could not find function "map"
map.cities(country = "Brazil") # Add a point for each city
Error in map.cities(country = "Brazil"): could not find function "map.cities"

Using a search engine, find the package, install it, and run the code.

library("maps")
map("world", "Brazil")
map.cities(country = "Brazil")