## R Packages: An Introduction

**Question:** What version of R do I run on my computer or laptop?

**Answer:** To get the information about the version of R, use the following command at R prompt.

> # get a version of R

> R.version.string

You will get a result like

[1] “R version 3.2.1 (2015-06-18)”

Note that a package in R language is a collection of objects that R Language can use. A package contains functions, data set, and documentation (which helps how to use the package) or other objects such as dynamically loaded libraries of already compiled code.

**Question:** How to check what packages are already installed?

**Answer:** To get a list of installed packages in R, write “library()” without quotation marks at the R prompt. R will first list all of the packages installed in the local R directory of your computer system and then it will list all packages installed globally on your computer system.

# list all packages installed

library()

You would get results like (note that results below are given as an example only, it’s not a complete list)

Packages in library ‘C:/Users/abcd/Documents/R/win-library/3.2’:

combinat combinatorics utilities

proftools Output Processing Tools for R

rgl 3D visualization device system (OpenGL)

Packages in library ‘C:/Program Files/R/R-3.2.1/library’:*KernSmooth* Functions for kernel smoothing for Wand & Jones (1995)*MASS* Support Functions and Datasets for Venables and Ripley’s MASS*Matrix* Sparse and Dense Matrix Classes and Methods*methods* Formal Methods and Classes

mgcv Mixed GAM Computation Vehicle with Automatic

Smoothness Estimation

Following is a very short list of packages installed in the local library.

Packages in library ‘C:/Users/imdad/Documents/R/win-library/3.5’:

*abind* Combine Multidimensional Arrays*AlgDesign* Algorithmic Experimental Design*askpass* Safe Password Entry for R, Git, and SSH*assertthat* Easy Pre and Post Assertions*tibble* Simple Data Frames*plyr* Tools for Splitting, Applying and Combining Data

For further detail on packages in R, see the link Packages in R Language.