R packages are a combination of R functions, compiled code, and sample data, and their storage directory is known as a library. By default, when R is installed, a set of packages gets installed and the rest of the packages you have to add when required.
A list of commands is given here to check which packages are present in your system:
>.libPaths()
The preceding command is used for getting or setting the library trees that R knows about. It gives the following result:
"C:/Program Files/R/R-3.3.1/library"
After this, execute the following command and it will list all the available packages:
>library()
There are two ways to install new packages.
CRAN stands for Comprehensive R Archive Network. It is a network of FTP web servers throughout the globe for storing identical, up-to-date versions of code and documentation for R.
The following command is used to install the package directly from the CRAN web page. You need to choose the appropriate mirror:
>install.packages("Package")
For example, if you need to install the ggplot2 or forecast package for R, the commands are as follows:
>install.packages("ggplot2") >install.packages("forecast")
Download the required R package manually and save the ZIP version at your designated location (let's say /DATA/RPACKAGES/) on the system.
For example, if we want to install ggplot2, then run the following command to install it and load it to the current R environment. Similarly, other packages can also be installed:
>install.packages("ggplot2", lib="/data/Rpackages/") >library(ggplot2, lib.loc="/data/Rpackages/")