Get admin boundaries for any country with R.

geo_bounds.R

#' @title Get administritive outlines for a country
#' @description using the geoBoundaires API, get the administritive polygon(s)
#' for a country
#' @param country character vector: a country name
#' @param admin_level character vector: the admin level to download
#' @param quiet logical, should st_read be quiet?
#' @return sf object of the outlines
#' @details check out the documentation for the geoboundaries API at:
#' geoBoundaries.org
#'
geo_bounds <- function(
    country,
    admin_level = c("ADM0", "ADM1", "ADM2"),
    quiet = TRUE) {
  # assertions
  country <- rlang::arg_match(
    country,
    unique(countrycode::countryname_dict$country.name.en)
  )
  admin_level <- rlang::arg_match(admin_level)
  assertthat::assert_that(inherits(quiet, "logical"))
  # get the iso3c code for the country
  country <- countrycode::countrycode(country,
    origin = "country.name",
    destination = "iso3c"
  )
  # get the geojson file
  url <- paste(
    "https://www.geoboundaries.org/api/current/gbOpen/",
    country, admin_level,
    sep = "/"
  )
  get <- httr::GET(url)
  cont <- httr::content(get, as = "parsed")

  sf::st_read(cont$gjDownloadURL, drivers = "GeoJSON", quiet = quiet)
}

usage:

x <- geo_bounds("United Kingdom")
plot(x["geometry"])