External libraries in R enhance the functionality by providing additional functions, datasets, and methods that are not available in the base R package.

Use the install.packages() function to install new libraries from CRAN (Comprehensive R Archive Network).

install.packages("package_name")

• This command only needs to be run once per R installation to add the library to your system.

install.packages("data.table")

• After installation, the package is permanently available on your machine, until or unless it is explicitly removed.

After installation, use the library() or require() function to load the library into your R session.

library(package_name)

• This command must be run every time you start a new R session and want to use the library.

library(data.table)

• Notice that we use data.table with the library() function and we use "data.table" with the install.packages() function.

• Installing a Library: Downloads and installs the package’s files to your R library directory. This is a one-time process for each R installation.

• Loading a Library: Makes the package’s functions available in your current R session. This must be done every time you start a new session and wish to use the package.

You can list all installed libraries using the installed.packages() function.

installed.packages()

Keep your libraries up to date to benefit from bug fixes and new features.

update.packages()

• Optionally, you can specify a package name to update only a specific library.

If needed, you can remove installed libraries using the remove.packages() function.

remove.packages("package_name")

Once a library is loaded, you can use its functions as if they were part of the base R language.

# Assuming `data.table` is already loaded
library(data.table)

# Create a data table
dt <- data.table(x = c(1, 2, 3), y = c(4, 5, 6))

# Print the data table
print(dt)

##        x     y
##    <num> <num>
## 1:     1     4
## 2:     2     5
## 3:     3     6