R Package Questions and Answers

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The post is about some important R package questions and answers. The R Package Questions and Answers are about how to load, install, and remove an R package.

R Package Questions and Answers

Question: What is an R Package?
Answer: The r package is a collection of objects that the R Language can use. A package contains functions, data sets, and documentation (which helps how to use the package) or other objects such as dynamically loaded libraries of already compiled code.

Question: How do I see which packages I have available?
Answer: To see which packages you have to use the command at the R prompt

library()

Question: Which packages do I already have?
Answer: To see what packages are installed one can use the installed.packages() command an R prompt. The output will show the packages installed.

installed.packages()
installed.packages()[1:5,]

Loading R Packages

Question: How one can load a Package in R language?
Answer: Basic packages are already loaded. If you want to load a downloaded version of packages use the command

library("package name")
library("car")

where the package name is the name of the package you want to load. Here in the example, we used the “car”, which means the “car” package will be loaded.

Getting Help in R Language

Question: How one can see the documentation of a particular package?
Answer: To see the documentation of a particular package use the command

library(help="package name")
help(package="package name")
help(package="car")
library(help="car")

for more information about getting help follow the link: Getting Help in R Language

Question: How do I see the help for a specific function?
Answer: To get help with a function in R use the command

help("function name")
? function name
?Manova
help("Manova")

Question: What functions and datasets are available in a package?
Answer: To check what functions and datasets are in a package using the help command at the R prompt. This will provide package information giving a list of functions and datasets.

help(package = "MASS")

Note that once a package is loaded, the help command can also be used with all available functions and datasets.

Installing and Removing R Packages

Question: How can one add or delete a package?
Answer: A package can be installed using the command

install.packages("package name")

and a package can be removed or deleted using the command

remove.packages("package name")
R Packages Questions and Answers R Faqs

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Data Frame in R Language

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Please load the required data set before running the commands given below in R FAQs related to the data frame. As an example for R FAQs about data frame in R, we are assuming the iris data set is available already in R. At R prompt write data(iris).

Naming/ Renaming Columns in a Data Frame

Question: How do you name or rename a column in a data frame?
Answer: Suppose you want to change/ rename the 3rd column of the data frame, then on R prompt write

names (iris)[,3] <- "new_name"

Suppose you want to change the second and third columns of the data frame

names(irisi)[c(2,4)] <- c("A", "D")

Note that names(iris) command can be used to find the names of each column in a data frame.

Question: How you can determine the column information of a data frame such as the “names, type, missing values” etc.?
Answer: There are two built-in functions in R to find the information about columns of a data frame.

str(iris)
summary(iris)
Data Frame in R Language

Exporting a Data Frame in R

Question: How a data frame can be exported in R so that it can be used in other statistical software?
Answer: Use the write.csv command to export the data in comma-separated format (CSV).

write.csv(iris, "iris.csv", row.names = FALSE)

Question: How one can select a particular row or column of a data frame?
Answer: The easiest way is to use the indexing notation []

Suppose you want to select the first column only, then at the R prompt, write

iris[,1]

Suppose we want to select the first column and also want to put the content in a new vector, then

new <- iris[,1]

Suppose you want to select different columns, for example, columns 1, 3, and 5, then

newdata <- iris[, c(1, 3, 5)]

Suppose you want to select a first and third row, then

iris[c(1,2), ]

Dealing with Missing Values in a Data Frame

Question: How do you deal with missing values in a data frame?
Answer: In R language it is easy to deal with missing values. Suppose you want to import a file named “file.csv” that contains missing values represented by a “.” (period), then on the R prompt write

data <- read.csv("file.csv", na.string = ".")

If missing values are represented as “NA” values then write

dataset <- read.csv("file.csv", na.string = "NA")

For the case of built-in data such (here iris), use

data <- na.omit(iris)

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FAQs about R Language

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The article is FAQs about R Language, that is R Frequently Asked Questions (R FAQs).

FAQS about R Language

Question: Why R language is named R?
Answer: The name of the R language is based on the first letters of its authors (Robert Gentleman and Ross Ihaka).

R Foundation

Question: What is the R Foundation?
Answer: The R Foundation is a non-profit organization working in the public interest, founded by the members of the R Core Team. This foundation provides support for the R project and other innovations in statistical computing and provides a reference point for individuals, institutions, or commercial enterprises who want to support or interact with the R development community. R foundation also holds and administers the copyright of R language software and its documentation. For more information about R Foundation follow the link https://www.R-project.org/foundation

Question: What is R-Forge?
Answer: R-Forge provides a central platform for the development of R packages, R-related software, etc. It is based on GForge and offers easy access to the best in SVN, daily built and checked R packages, mailing lists, bug tracking, message board or forum, website hosting, permanent file archival, full backups, and total web-based administration. For more information see

  • The R-Forge web page
  • Stefan Theußl and Achim Zeileis (2009), “Collaborative software development using R-Forge”, The R Journal, 1(1), 9-14.

Mailing Lists of R

Question: What mailing lists exist for R language?
Answer: There are four mailing lists devoted to R language

  • R-announce: A moderated mailing list for major announcements about the R development and the availability of new R code.
  • R-packages: A moderated mailing list for an announcement on the availability of new or further enhanced contributed packages.
  • R-help: The main R mailing list for discussion and problems and solutions using R, announcements about the development of R, and the availability of new R code. R-help is intended for people who want to use R to solve problems.
  • R-devel: A mailing list for questions and discussions about code development in R language.

R Language Documentation

Question: What documentation exists for R language?
Answer: For most of the R functions and variables in R online documentation exists and this documentation can be printed on screen by typing help(name) or “?name” at the R prompt, where the name is the name of the topic for which help is required. The R documentation can also be made available in PDF and HTML formats and as a hard copy via LaTeX. The up-to-date HTML version of R documentation is always available for web browsers at http://stat.ethz.ch/R-manual. A lot of R books and manuals are also available as R documentation.

R documentation refers to the various resources available to help you learn and use the R programming language.

  • Official R Language Documentation: The R Project itself maintains a collection of manuals and guides covering different aspects of the R language. This includes (i) an introduction to R, (ii) Reference manuals for specific functions and packages, and (iii) information on using the R interface.
  • Package Documentation: Many R packages also have their documentation, which one can access within the R environment using the help function. These help files (package documentation) explain how to use the specific functions and features provided by the package.
  • Online Resources: Many online resources provide tutorials, explanations, and examples for working with R Language. These can be a great way to learn the language and find solutions to specific problems https://rdocumentation.org/.
  • Books and Other Publications: There are also several books and other publications available that cover R in more depth. These books and publications can help get a more comprehensive understanding of the language and its capabilities.
RFAQs: Frequently Asked Questions About R

How to get help in R follow the link Getting Help in R Language.

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