3  .R and helpfiles

• .R files contain the functions your packge will provide

• Don’t code helpfiles (.Rd files in the man folder) yourself

• Use Roxygen syntax through the roxygen2 package

  • Roxygen syntax lines begin #'

• To additionally use markdown syntax within roxygen syntax add the following line to your DESCRIPTION file

  Roxygen: list(markdown = TRUE)

• Your .R files will look something like the following, i.e., roxygen code for the helpfile for a function before the actual R code of the function

  #' The length of a string
  #'
  #' Technically this returns the number of "code points", in a string. One
  #' code point usually corresponds to one character, but not always. For example,
  #' an u with a umlaut might be represented as a single character or as the
  #' combination a u and an umlaut.
  #'
  #' @inheritParams str_detect
  #' @return A numeric vector giving number of characters (code points) in each
  #'    element of the character vector. Missing string have missing length.
  #' @seealso [stringi::stri_length()] which this function wraps.
  #' @export
  #' @examples
  #' str_length(letters)
  #' str_length(NA)
  #' str_length(factor("abc"))
  #' str_length(c("i", "like", "programming", NA))
  str_length <- function(string) {
    ...
  }

• Running devtools::document() will generate your .Rd files from your .R files