Write Roxygen Docs

Complete roxygen2 docs → R fns, datasets, classes.

Use When

• New exported fn → docs
• Internal helper fns
• Pkg datasets
• S3/S4/R6 classes + methods
• Fix doc-related R CMD check notes

In

• Required: R fn|dataset|class to doc
• Optional: Related fns → cross-ref (@family, @seealso)
• Optional: Export fn?

Do

Step 1: Fn Docs

Roxygen comments directly above fn:

#' Compute the weighted mean of a numeric vector
#'
#' Calculates the arithmetic mean of `x` weighted by `w`. Missing values
#' in either `x` or `w` are handled according to the `na.rm` parameter.
#'
#' @param x A numeric vector of values.
#' @param w A numeric vector of weights, same length as `x`.
#' @param na.rm Logical. Should missing values be removed? Default `FALSE`.
#'
#' @return A single numeric value representing the weighted mean.
#'
#' @examples
#' weighted_mean(1:5, rep(1, 5))
#' weighted_mean(c(1, 2, NA, 4), c(1, 1, 1, 1), na.rm = TRUE)
#'
#' @export
#' @family summary functions
#' @seealso [stats::weighted.mean()] for the base R equivalent
weighted_mean <- function(x, w, na.rm = FALSE) {
  # implementation
}

Got: Complete roxygen w/ title, desc, @param per param, @return, @examples, @export.

If err: Unsure tag → ?roxygen2::rd_roclet. Common omission @return → CRAN required for all exports.

Step 2: Essential Tags

Got: Required tags ID'd. Exports have @param, @return, @examples, @export minimum.

If err: Tag unfamiliar → roxygen2 docs for usage + syntax.

Step 3: Doc Datasets

Create R/data.R:

#' Example dataset of city temperatures
#'
#' A dataset containing daily temperature readings for major cities.
#'
#' @format A data frame with 365 rows and 4 variables:
#' \describe{
#'   \item{date}{Date of observation}
#'   \item{city}{City name}
#'   \item{temp_c}{Temperature in Celsius}
#'   \item{humidity}{Relative humidity percentage}
#' }
#' @source \url{https://example.com/data}
"city_temperatures"

Got: R/data.R has roxygen blocks per dataset w/ @format describing structure + @source for provenance.

If err: R CMD check warns undocumented dataset → ensure quoted string ("city_temperatures") exactly matches obj name saved w/ usethis::use_data().

Step 4: Doc Pkg

Create R/packagename-package.R:

#' @keywords internal
"_PACKAGE"

## usethis namespace: start
## usethis namespace: end
NULL

Got: R/packagename-package.R exists w/ @keywords internal + "_PACKAGE" sentinel. devtools::document() generates man/packagename-package.Rd.

If err: R CMD check reports missing pkg doc page → verify file R/<packagename>-package.R + contains "_PACKAGE".

Step 5: Special Cases

Fns w/ dots in names (S3 methods):

#' @export
#' @rdname process
process.myclass <- function(x, ...) {
  # S3 method
}

Reuse docs w/ @inheritParams:

#' @inheritParams weighted_mean
#' @param trim Fraction of observations to trim.
trimmed_mean <- function(x, w, na.rm = FALSE, trim = 0.1) {
  # implementation
}

No visible binding fix w/ .data pronoun:

#' @importFrom rlang .data
my_function <- function(df) {
  dplyr::filter(df, .data$column > 5)
}

Got: Special cases (S3 methods, inherited params, .data pronoun) documented correctly. @rdname groups S3 methods. @inheritParams reuses params w/o duplicate.

If err: R CMD check warns "no visible binding for global variable" → #' @importFrom rlang .data or utils::globalVariables() last resort.

Step 6: Generate Docs

devtools::document()

Got: man/ updated w/ .Rd files per documented obj. NAMESPACE regenerated w/ correct exports + imports.

If err: Roxygen syntax errs. Common: unclosed brackets in \describe{}, missing #' prefix, invalid tag names. Re-run devtools::document() after fix.

Check

• Every exported fn has @param, @return, @examples
• devtools::document() runs no errs
• devtools::check() no doc warnings
• @family tags group correctly
• Examples run no errs (devtools::run_examples())

Traps

• Missing @return: CRAN requires all exports doc return value
• Examples need internet/auth: Wrap \dontrun{} w/ comment why
• Slow examples: \donttest{} for examples that work but slow for CRAN
• Markdown in roxygen: Enable Roxygen: list(markdown = TRUE) in DESCRIPTION
• Forget devtools::document(): Man pages generated, not hand-written

→

• create-r-package — initial pkg setup including roxygen config
• write-testthat-tests — test fns you doc
• write-vignette — long-form docs beyond fn ref
• submit-to-cran — doc requirements for CRAN