R/gisco_get_grid.R

In giscoR: Download Map Data from GISCO API - Eurostat

#' Get grid cells covering covering Europe for various resolutions
#'
#' @description
#' These datasets contain grid cells covering the European land
#' territory, for various resolutions from 1km to 100km. Base statistics such
#' as population figures are provided for these cells.
#'
#' @family misc
#'
#' @return A `POLYGON/POINT` [`sf`][sf::st_sf] object.
#'
#' @author dieghernan, <https://github.com/dieghernan/>
#'
#' @source
#' <https://ec.europa.eu/eurostat/web/gisco/geodata/grids>
#'
#' @param resolution Resolution of the grid cells on kms. Available values are
#' `"1"`, `"2"`, `"5"`, `"10"`, `"20"`, `"50"`, `"100"`. See **Details**.
#'
#' @param spatialtype Select one of `"REGION"` or `"POINT"`.
#'
#' @inheritParams gisco_get_countries
#'
#' @inheritSection gisco_get_countries About caching
#'
#' @details
#'
#' Files are distributed on EPSG:3035.
#'
#' The file sizes range is from 428Kb (`resolution = "100"`)
#' to 1.7Gb `resolution = "1"`. For resolutions 1km and 2km you would
#' need to confirm the download.
#'
#' @note
#' There are specific downloading provisions, please see
#' <https://ec.europa.eu/eurostat/web/gisco/geodata/grids>
#'
#' @examplesIf gisco_check_access()
#' \donttest{
#' grid <- gisco_get_grid(resolution = 20)
#'
#' # If downloaded correctly proceed
#'
#' if (!is.null(grid)) {
#'   library(dplyr)
#'
#'   grid <- grid %>%
#'     mutate(popdens = TOT_P_2021 / 20)
#'
#'   breaks <- c(0, 0.1, 100, 500, 1000, 5000, 10000, Inf)
#'
#'   # Cut groups
#'   grid <- grid %>%
#'     mutate(popdens_cut = cut(popdens,
#'       breaks = breaks,
#'       include.lowest = TRUE
#'     ))
#'
#'   cut_labs <- prettyNum(breaks, big.mark = " ")[-1]
#'   cut_labs[1] <- "0"
#'   cut_labs[7] <- "> 10 000"
#'
#'   pal <- c("black", hcl.colors(length(breaks) - 2,
#'     palette = "Spectral",
#'     alpha = 0.9
#'   ))
#'
#'   library(ggplot2)
#'
#'   ggplot(grid) +
#'     geom_sf(aes(fill = popdens_cut), color = NA, linewidth = 0) +
#'     coord_sf(
#'       xlim = c(2500000, 7000000),
#'       ylim = c(1500000, 5200000)
#'     ) +
#'     scale_fill_manual(
#'       values = pal, na.value = "black",
#'       name = "people per sq. kilometer",
#'       labels = cut_labs,
#'       guide = guide_legend(
#'         direction = "horizontal",
#'         nrow = 1
#'       )
#'     ) +
#'     theme_void() +
#'     labs(
#'       title = "Population density in Europe (2021)",
#'       subtitle = "Grid: 20 km.",
#'       caption = gisco_attributions()
#'     ) +
#'     theme(
#'       text = element_text(colour = "white"),
#'       plot.background = element_rect(fill = "grey2"),
#'       plot.title = element_text(hjust = 0.5),
#'       plot.subtitle = element_text(hjust = 0.5, face = "bold"),
#'       plot.caption = element_text(
#'         color = "grey60", hjust = 0.5, vjust = 0,
#'         margin = margin(t = 5, b = 10)
#'       ),
#'       legend.position = "bottom",
#'       legend.title.position = "top",
#'       legend.text.position = "bottom",
#'       legend.key.height = unit(0.5, "lines"),
#'       legend.key.width = unit(1, "lines")
#'     )
#' }
#' }
#' @export
gisco_get_grid <- function(resolution = "20",
                           spatialtype = c("REGION", "POINT"),
                           cache_dir = NULL, update_cache = FALSE,
                           verbose = FALSE) {
  resolution <- as.character(resolution)
  validres <- as.character(c(1, 2, 5, 10, 20, 50, 100))

  if (!resolution %in% validres) {
    stop("resolution should be one of ", paste0(validres, collapse = ", "))
  }

  spatialtype <- match.arg(spatialtype)
  valid <- c("REGION", "POINT")

  translate <- c("surf", "point")
  ftrans <- translate[valid == spatialtype]
  filename <- paste0("grid_", resolution, "km_", ftrans, ".gpkg")
  api_entry <- "https://gisco-services.ec.europa.eu/grid"
  url <- file.path(api_entry, filename)

  local <- file.path(gsc_helper_cachedir(cache_dir), filename)
  exist_local <- file.exists(local)

  gsc_message(verbose & exist_local, "File exits on local cache dir")

  # nocov start
  if (resolution %in% c("1", "2") && isFALSE(exist_local)) {
    sel <- menu(c("Yes", "No"),
      title = "You are about to download a large file (>500M). Proceed?"
    )
    if (sel != 1) {
      stop("Execution halted")
    }
  }
  # nocov end


  localfile <- gsc_api_cache(url, filename, cache_dir, update_cache, verbose)

  if (is.null(localfile)) {
    return(NULL)
  }

  size <- file.size(localfile)
  class(size) <- "object_size"
  gsc_message(verbose, format(size, units = "auto"))

  data_sf <- try(
    sf::st_read(localfile,
      quiet = !verbose,
      stringsAsFactors = FALSE
    ),
    silent = TRUE
  )


  # nocov start
  if (inherits(data_sf, "try-error")) {
    stop(
      "\n Malformed ",
      localfile,
      "\n Try downloading from: \n",
      url,
      "\n to your cache_dir folder"
    )
  }
  # nocov end

  data_sf <- sf::st_make_valid(data_sf)

  return(data_sf)
}