Seeking Help

Adapted from Software Carpentry

Overview

Questions:

  • How can I get help in R?

Objectives:

  • Use R help files and resources
  • Find packages for specific tasks
  • Seek help from peers
  • Use generative AI responsibly

Reading Help Files

Access help for any function:

?function_name
help(function_name)

Help pages include: Description, Usage, Arguments, Details, Value, See Also, and Examples.

For special operators, use quotes or backticks:

?"<-"
?`<-`
TipRunning Examples

Highlight code examples in help pages and hit Ctrl+Return to run them in RStudio.

Getting Help

Package Vignettes

Packages often include tutorials and extended examples:

vignette()                    # list all vignettes
vignette(package="dplyr")     # list dplyr vignettes
vignette("dplyr")             # open specific vignette

See RStudio cheatsheets for common packages.

Finding Packages

CRAN Task Views organizes packages by topic.

Getting Help from Others

Online Resources

  • Search the internet: Paste your error message and “R” into a search engine
    • StackOverflow is particularly helpful; use the [r] tag
    • Note: Understand code before copying it
  • Ask colleagues: Share your problem with someone more experienced
  • Rubber duck debugging: Explaining your problem out loud often reveals the solution

Formulating Good Questions

When asking for help, provide:

dput(your_data)        # share your data reproducibly
sessionInfo()          # share your R environment

Generative AI Tools

Tools like ChatGPT can provide helpful suggestions. However:

  • Responses are not always reliable - verify accuracy
  • They may generate plausible-sounding but incorrect information
  • You need domain knowledge to evaluate code quality
  • Later, focus on building your own problem-solving skills
NoteChallenge 1: Understanding the c Function

Look at the help page for the c function. What kind of vector do you expect will be created if you evaluate the following:

c(1, 2, 3)
c('d', 'e', 'f')
c(1, 2, 'f')

The c() function creates a vector, and all elements of a vector must be the same type. In the first two cases, the elements are already the same type. But in the third case, R will convert all the numbers to characters to make them all the same type.

c(1, 2, 3)      # numeric vector
c('d', 'e', 'f')  # character vector
c(1, 2, 'f')    # character vector: "1" "2" "f"
NoteChallenge 2: Understanding paste

Look at the help for the paste function. You will need to use it later. What’s the difference between the sep and collapse arguments?

sep controls how elements are separated within a single call to paste, while collapse controls how multiple results are combined into a single string.

paste("a", "b", sep = "-")         # "a-b"
paste(c("a", "b"), c("c", "d"), sep = "-")  # "a-c" "b-d"
paste(c("a", "b"), c("c", "d"), sep = "-", collapse = " & ")  # "a-c & b-d"
NoteChallenge 3: Finding Functions for Reading Data

Use help to find a function (and its associated parameters) that you could use to load data from a tabular file in which columns are delimited with “ (tab) and the decimal point is a”.” (period). This check for decimal separator is important, especially if you are working with international colleagues, because different countries have different conventions for the decimal point (i.e. comma vs period).

Hint: use ??"read table" to look up functions related to reading in tabular data.

The standard R function for reading tab-delimited files with a period as decimal separator is read.delim(). You can also use read.table() with appropriate arguments:

read.delim(file, header = TRUE, sep = "\t", dec = ".")
# or
read.table(file, header = TRUE, sep = "\t", dec = ".")

Resources

Key Points

  • Use help() or ? to get online help in R
  • Use ?? for fuzzy searches when you don’t know the exact function name
  • R help files provide detailed documentation including usage, arguments, and examples
  • CRAN Task Views can help you find packages for specific tasks
  • When asking for help, provide reproducible examples and session information