Packages add new capabilities to R.

Package contains: - DESCRIPTION – Name, short description, version, dependencies - R code - Man pages (help) for new code

Package may also contain: - SRC: C, Fortran, Java, … code to add functionality or to link to other tools (e.g., a database) - Data: Sample data to test functions - Vingettes: Longer narrative help that describes how to do something.

• CRAN: Comprehensive R Archive Network

• 13,000 packages: https://cran.r-project.org/

• Mirrors around the world https://cloud.r-project.org/
• GitHub: Many package sources are maintained there.
• Private Repositories
• Search Stack Overflow and similiar sites.

1. First, you must download the package code (either source or compiled to your computer)
2. Then the package must be installed in a library directory that R knows about.
   

• The install.packages(name) function will do steps 1 and 2

1. When you want to use functions from the package, you need to load them into the workspace.
   

• This can be done with library(name) or require(name).

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summary(cars)

##      speed           dist       
##  Min.   : 4.0   Min.   :  2.00  
##  1st Qu.:12.0   1st Qu.: 26.00  
##  Median :15.0   Median : 36.00  
##  Mean   :15.4   Mean   : 42.98  
##  3rd Qu.:19.0   3rd Qu.: 56.00  
##  Max.   :25.0   Max.   :120.00