Help() Function in R
R’s built-in help() function provides vital function and feature information. You can visit the help page for any command by typing help() with the command name in parenthesis (e.g., help(lm)) or using the question mark shortcut (?sample). If you don’t know the command name, use help.search(“keyword”) or the?? shortcut to open a browser with documentation links.
A Function Description, Usage section showing how to type it with its arguments in order, Arguments section explaining each argument, and Value section stating what the function returns are on each help page. Any help page’s Examples section at the bottom, which gives guaranteed-to-work code that can be run in the console using example(), is quite helpful. For R to find a function’s help page, the package must be loaded.
Using help() and ? for Specific Functions
Help() or the question mark? is the easiest approach to get help when you know the name of the function or object. This opens the function’s help page in RStudio’s bottom-right pane’s Help tab.
Syntax is simple:
> help(function_name)
> ?function_name
Type help(lm) or?lm to learn about the linear model function lm(). When using operators, special characters, or reserved terms, quote them. For instance, “for” describes for loops, while “less than” illustrates the “less than” operator. Help Page Structure The help pages in R are comprehensive, although beginners may find them technical. Often, scanning for pertinent sections and focusing on the examples at the bottom works best. Help pages often have these sections:
Usage: An example of how the function is typed shows its parameters in sequence and their default values, if any. This helps summarize the function’s syntax.
Arguments: R functions receive arguments as placeholders for data or parameters to modify their behavior. Functions have formal parameters or arguments specified in parentheses after the function keyword. In myFunction <- function(arg1, arg2,…), the formal parameters are arg1 and arg2.
Details: The Details section is standard in R Programming function help pages. This section details a function’s purpose and operation beyond the Description section. The function’s author can explain its methodology, warn users of critical considerations or actions, and provide any other information that may help users execute the function effectively in the Details section. For instance, the sample function’s help page’s Details section explains how to weight components with the optional prob argument.
Value: R typically uses value to refer to the single object a function returns after execution. This essential R programming idea is documented in the Value portion of every function’s help page, which describes what the function delivers when performed. R’s main engines, functions, take arguments, calculate, and return values.
See Also: R’s help pages’ “See Also” feature helps users navigate structured documentation. The help() command or? shortcut opens any function’s help page. The “See Also” section of the help page lists related R functions. The highlight that these function names are linked, making it easy to access their help files. This makes the “See Also” section useful for finding complimentary or alternate task functions.
Examples: Most help pages end with working code. Running this code helps you learn by doing and see the function in action. Args() displays a function’s arguments without documentation. Remember that help() and? only find functions in packages loaded in your R session.
Example:
# Compact demo without opening long help pages
# Show function arguments
cat("Arguments of mean():\n")
print(args(mean))
cat("\nArguments of lm():\n")
print(args(lm))
# Example calculation
x <- c(1, 2, 3, 4, 5)
cat("\nVector x:\n")
print(x)
cat("\nMean of x:\n")
print(mean(x))Output:
Arguments of mean():
function (x, ...)
NULL
Arguments of lm():
function (formula, data, subset, weights, na.action, method = "qr",
model = TRUE, x = FALSE, y = FALSE, qr = TRUE, singular.ok = TRUE,
contrasts = NULL, offset, ...)
NULL
Vector x:
[1] 1 2 3 4 5
Mean of x:
[1] 3Searching for Topics with help.search() and ??
Use help.search() or its shortcut,??, to run a keyword search in R when you don’t know the function name. This program helps you find functions relevant to a topic or remember a function’s name in R’s documentation. While the entire command requires a character string, like help.search(“combination”), the shortcut can be used straight with the keyword, like??”histograms”.
Both techniques do a “Google-style search” of all installed package documentation, not just loaded ones. After the search, R will launch a web or help browser with links to relevant help pages, which you can browse to find the command. This functionality, known as “the help page for the help page,” guides you through R’s rich documentation.
Running Built-in Examples with example()
The R example() function makes it easy to run the built-in example code in a command’s help documentation. Most R function help pages provide an Examples section at the bottom with guaranteed-working code and examples of how to use the function. R will execute all of the code from that section on the console by invoking example() with the function name as an argument, such as example(rep) or example(seq). Learning by example is great since it shows the function in operation and explains its capabilities. You can highlight commands in the help box and submit them for assessment if you don’t want to run all the examples.
Getting More Help
R offers more means to comprehend its functionalities and a large community for help beyond these built-in features.
Viewing Code: Most functions in R may be seen, which helps explain their operation. Typing the function name without parentheses in the console displays the code inside the function object (simplest method). Typing IQR displays its code. Use args() to see a function’s arguments and body() to see its code. In RStudio, pressing F2 on a function name opens its code in the editor.
External Resources: R Programming community helps. Not satisfied with the built-in documentation? Ask Stack Overflow or the R-help mailing group. Ask for help with a “reproducible example” a little piece of code that explains your problem to improve your chances of getting a relevant answer. Rseek.org helps find R-related content online.
These help-seeking tactics can help you confidently navigate the vast R functions landscape, solving problems faster and improving your programming skills.