R/str_comma.R

In shirewoman2/LaurasHelpers: Miscellaneous Helper Functions for Common PK or Analytical Chemistry Tasks

#' Collapse a vector of character strings into one readable string, separated by
#' commas and by "and"
#'
#' \code{str_comma} combines multiple character strings into one and makes them
#' more readable by separating those strings with commas and "and" as
#' appropriate. The place I had in mind for using this is in RMarkdown documents
#' where you want to insert a comment in the text that calls on a character
#' vector. For example, say you want to note in a text chunk which subjects in a
#' study have some measurement that is two standard deviations above the mean.
#' Rather than using only, e.g., \code{stringr::str_c(StudyOutliers, collapse =
#' ", ")}, you could have it include the "and" in the appropriate location and
#' make your final document more polished, readable, and professional.
#'
#'
#' @param x values to be concatenated
#' @param oxford TRUE or FALSE for whether to use the Oxford comma
#'
#' @return Returns a single, collapsed character string
#' @export
#'
#' @examples
#' str_comma(LETTERS[1:2])
#' str_comma(LETTERS[1:4])
#' str_comma(LETTERS[1:4], oxford = FALSE)
#'
#'
str_comma <- function(x, oxford = TRUE){

      if(length(x) <= 2){
            Out <- stringr::str_c(x, collapse = " and ")
      } else {
            Last <- x[length(x)]
            Others <- x[1:(length(x) - 1)]
            Out <- stringr::str_c(
                  paste0(c(stringr::str_c(Others, collapse = ", "),
                           "and", Last), collapse = " "))
            if(oxford){
                  Out <- sub(" and", ", and", Out)
            }
      }

      return(Out)
}