R/KFME_grid.R

In RCzechia: Spatial Objects of the Czech Republic

#' KFME grid cells (faunistické čtverce) of the Czech Republic
#'
#' Function returning grid covering the Czech Republic according to the Kartierung der Flora Mitteleuropas methodology.
#'
#' The function returns a `sf` data frame of grid cells. Depending on the value of parameter `resolution` either low resolution (26×42 cells - default) with labels in 4 digit format (e.g. Hrčava = 6479) or high resolution (104×168 cells) with labels in 4 digit + 1 letter format (e.g Hrčava = 6479c).
#'
#' Raw version of the dataset is available for download for use in non-R setting on <https://rczechia.jla-data.net/kfme_czechia.gpkg>.
#'
#' @param resolution Should the function return high or low resolution shapefile? Allowed values are "low" and "high". Default is "low".
#'
#' @return `sf` data frame with 1092 rows in low resolution and 4368 rows in high resolution
#'
#' \describe{
#'   \item{ctverec}{KFME code of the grid cell; depending on value of `resolution` parameter either 4 digits, or 4 digits + 1 letter}
#' }
#'
#' @examples
#' library(ggplot2)
#'
#' ggplot() +
#'   geom_sf(data = republika("low")) +
#'   geom_sf(data = KFME_grid("low"), fill = NA)
#'
#' @export

KFME_grid <- function(resolution = "low") {
  if (!is.element(resolution, c("high", "low"))) {
    stop(paste(resolution, "is not a valid resoulution; recognized values are \"high\" or \"low\"."))
  }

  if (resolution == "low") {
    return(faunisticke_ctverce)
  } else {
    return(faunisticke_ctverecky)
  }
}