R/get_data.R

In rnaturalearth: World Map Data from Natural Earth

#' Get data from within the package
#'
#' returns world country polygons at a specified scale, used by ne_countries()
#'
#' @param scale scale of map to return, one of \code{110}, \code{50}, \code{10},
#' \code{'small'}, \code{'medium'}, \code{'large'}
#'
#' @param type country type, one of 'countries', 'map_units', 'sovereignty',
#' 'tiny_countries'
#'
#' @return A \code{SpatialPolygonsDataFrame} object.
get_data <- function(
    scale = 110,
    type = c(
      "countries",
      "map_units",
      "sovereignty",
      "tiny_countries"
    )) {
  # check on permitted scale arg, convert names to numeric
  scale <- check_scale(scale)

  # check permitted type arg
  type <- match.arg(type)

  # tiny_countries not available at scale 10
  if (type == "tiny_countries" && scale == 10) {
    stop("tiny_countries are not available at scale 10, use scale 50 or 110")
  }

  # check for the data packages and try to install if not there
  # avoid this check for one example dataset in this package (i.e. countries110)

  if (scale == 10) {
    check_rnaturalearthhires()
  } else if (!(scale == 110 && type == "countries")) {
    check_rnaturalearthdata()
  }

  # choose which map based on type and scale (stored in different packages)

  if (scale == 110 && type == "countries") {
    spdf <- getExportedValue("rnaturalearth", paste0(type, scale))
  } else if (scale == 110 || scale == 50) {
    spdf <- getExportedValue("rnaturalearthdata", paste0(type, scale))
  } else if (scale == 10) {
    spdf <- getExportedValue("rnaturalearthhires", paste0(type, scale))
  }


  return(spdf)
}