R/get_data_path.R

In pastclim: Manipulate Time Series of Climate Reconstructions

#' Get the data path where climate reconstructions are stored
#'
#' This function returns the path where climate reconstructions are stored.
#'
#' The path is stored in an option for `pastclim` named `data_path`. If
#' a configuration file was saved when using [set_data_path()], the path
#' is retrieved from a file named "pastclim_data.txt", which
#' is found in the directory returned by
#' `tools::R_user_dir("pastclim","config")` (i.e.
#' the default configuration directory for the package as set in R >= 4.0).
#'
#' @param silent boolean on whether a message is returned when data_path is
#' not set (i.e. equal to NULL)
#' @returns the data path
#' @export

get_data_path <- function(silent = FALSE) {
  # if the package already initiliased
  if (!is.null(getOption("pastclim.data_path"))) {
    return(getOption("pastclim.data_path"))
  } else { # get the info from the config file
    # if the path was not set yet, return a message
    if (!file.exists(file.path(
      tools::R_user_dir("pastclim", "config"),
      "pastclim_data.txt"
    ))) {
      if (!silent) {
        message(
          "A default data_path was not set for pastclim;\n",
          "use `set_data_path()` to set it."
        )
      }
      return(NULL)
    }
    path_to_nc <- utils::read.table(file.path(
      tools::R_user_dir("pastclim", "config"),
      "pastclim_data.txt"
    ))[1, 1]
    if (!dir.exists(path_to_nc)) {
      warning(
        "The path ", path_to_nc, " from the config file does not exist!\n",
        "You can reset the path with `set_data_path`."
      )
      return(NULL)
    }
    return(path_to_nc)
  }
}