R/write_obj.R

In qtkit: Quantitative Text Kit

#' Write an R object as a file
#'
#' @description This function is a wrapper around `dput` that allows you
#' to write an R object as part of a knitr document as an output for
#' later use. It is designed to be used in a code block. The file name, if
#' not specified, will be the label of the code block. Use the standard
#' `dget` function to read the file back into an R session.
#'
#' @param obj The R object to be written.
#' @param file The name of the file to be written. If not specified, the
#' label of the code block will be used.
#' @param target_dir The directory where the file will be written. If not
#' specified, the current working directory will be used.
#' @param ... Additional arguments to be passed to `dput`.
#'
#' @return The path of the written file.
#'
#' @examples
#' \dontrun{
#' obj_dir <- file.path(tempdir(), "obj")
#'
#' # Write a data frame as a file
#' write_obj(
#'  obj = mtcars,
#'  file = "mtcars_data",
#'  target_dir = obj_dir)
#'
#' # Read the file back into an R session
#' my_mtcars <- dget(file.path(obj_dir, "mtcars_data"))
#'
#' unlink(obj_dir)
#' }
#' @importFrom knitr opts_current
#'
#' @export write_obj
#' @keywords publishing
write_obj <-
  function(
    obj,
    file = NULL,
    target_dir = NULL,
    ...) {
  # Retrieve the label of the current code chunk
  block_label <- knitr::opts_current$get("label")
  # If file name is not specified, use the block label as the file name
  if (is.null(file)) {
    if (is.null(block_label)) {
      # Stop execution and throw an error if both file name
      # and block label are not specified
      stop("file must be specified")
    }
    # Use the block label as the file name
    file <- block_label
  }
  # If target directory is not specified, use the current working directory
  if (is.null(target_dir)) {
    target_dir <- getwd()
  }
  # If the target directory does not exist, create it
  if (!dir.exists(target_dir)) {
    dir.create(target_dir, recursive = TRUE)
    # Output a message indicating that the directory has been created
    message("Directory created: ", target_dir)
  }
  # Construct the full file path
  file <- file.path(target_dir, file)
  # Save the object to the specified file
  dput(obj, file, ...)
  # Return the file path, invisibly
  return(invisible(file))
}