In olobiolo/Rdlazer: Resources for Teaching R

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

Packages

• a package is a collection of files containing code, i.e. primarily functions
• a package can also contain data, either as raw files or as code that generates the data
• some packages contain only data - this allows the data to be neatly documented
• a package is a common way of distributing code, ensuring it will be readily usable
• in other languages (e.g. Python, or C++) this is usually called a library

the library

• before they can be used, packages have to be installed
• install packages with install.packages
• this downloads the specified packages from a repository and installs them
• the default repository is CRAN: the entity that keeps, maintains, and delevops the R language
• there are other repositories, e.g. BioConductor, Github
• non-CRAN repositories can have other ways to install packages
• all installed packages are kept in a directory called the library
• list all installed packages with .packages(all.available = TRUE)
• for more comprehensive view use installed.packages
• uninstall packages with remove.packages
• installing a package does not mean you can access its contents, not quite yet

packages in action

• a package has a namespace, a collection of names to which values are assigned
• objects that are made accessible to the user are said to be exported
• a namespace also contains names of objects that are imported from other packages but that is another story
• a package can be attached to a session with library
• the contents of the namespace become accessible

hint('0.1.2')

library(Rdlazer)
hint('0.1.2')

\newline

• note that attaching Rdlazer causes masking of two objects from datasets
• masking means that two objects exist under one name
• by defualt the name will access the object that was attached later
• you can refer to them unambiguously with the special operator ::

head(mtcars)

head(Rdlazer::mtcars)

head(datasets::mtcars)

• the :: operator can also be used to access namespaces of packages that have been installed but not attached

head(USMortality)

head(lattice::USMortality)

\newline

• detach a package from the current session with detach("package:packagename", unload = TRUE)
• the currently attached packages can be viewed with the function .packages

# .packages returns invisibly
(.packages())

• another way is to view the search list with search; check the Environments vignette for an explanation

olobiolo/Rdlazer documentation built on Aug. 6, 2022, 11:37 a.m.