Package installation (install.packages) in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the install.packages() function in R?

The install.packages() function is used to download and install new packages from CRAN or other repositories so you can use additional functions in R.

beginner

How do you install the package named dplyr in R?

You run install.packages("dplyr") in the R console. This downloads and installs the dplyr package.

intermediate

Can you use install.packages() to update an already installed package?

Yes, running install.packages() again for a package will update it to the latest version if a newer one is available.

intermediate

What happens if you try to install a package that is already installed?

R will check the installed version and if it is the latest, it will not reinstall. Otherwise, it updates the package.

beginner

Why do you need to install a package only once but load it every time you start R?

Installing downloads and sets up the package on your computer. Loading with library() makes the package functions available in your current R session.

Which function do you use to install a package in R?

A require()

B install.packages()

C library()

D load.package()

The install.packages() function downloads and installs packages. library() and require() load installed packages.

What argument do you pass to install.packages() to install the package 'ggplot2'?

A "ggplot2"

B ggplot2

C install ggplot2

D package = ggplot2

You must pass the package name as a string, so use "ggplot2".

If you want to install a package from a specific CRAN mirror, which argument do you use?

A url

B mirror

C repos

D source

The repos argument lets you specify the CRAN mirror URL.

After installing a package, what function do you use to start using it in your R session?

A library()

B install.packages()

C load()

D use()

Use library() to load the package into your current R session.

What happens if you run install.packages() for a package that is already installed and up to date?

A It causes an error

B It uninstalls the package

C It installs an older version

D Nothing, it skips reinstalling

R checks the version and skips reinstalling if the package is already up to date.

Explain the difference between installing a package and loading a package in R.

Think about what happens once versus what happens every time you start R.

Describe how you would install a package from a specific CRAN mirror.

Look for the argument that controls the source location.