R/region_shp.R

In mregions: Marine Regions Data from 'Marineregions.org'

#' Get a region shp file
#'
#' @export
#' @importFrom sf read_sf
#' @param key (character) Region key, of the form `x:y`, where
#' `x` is a namespace (e.g., `MarineRegions`), and `y` is
#' a region (e.g., `eez_33176`)
#' @param name (character) Region name, if you supply this, we search
#' against titles via [mr_names()] function
#' @param maxFeatures (integer) Number of features
#' @param overwrite (logical) Overwrite file if already exists.
#' Default: `FALSE`
#' @param read (logical) To read in as spatial object. If `FALSE` a path
#' given back. if `TRUE`, you need the `rgdal` package installed.
#' Default: `FALSE`
#' @param filter (character) String to filter features on
#' @param ... Curl options passed on to [httr::GET()]. since we
#' use caching, note that if you've made the exact same request before and the
#' file is still in cache, we grab the cached file and don't make an HTTP
#' request, so any curl options passed would be ignored.
#'
#' @return A `SpatialPolygonsDataFrame` if `read = TRUE`, or a path to
#' a SHP file on disk if `read = FALSE`.
#'
#' @details We use \pkg{rappdirs} to determine where to cache data depening on
#' your operating system. See `rappdirs::user_cache_dir("mregions")` for
#' location on your machine
#'
#' We cache based on the name of the region plus the `maxFeatures`
#' parameter. That is to say, you can query the same region name, but
#' with different `maxFeatures` parameter values, and they will get
#' cached separately. You can clear the cache by going to the directory at
#' `rappdirs::user_cache_dir("mregions")` and deleting the files.
#'
#' We use `stringsAsFactors = FALSE` inside of `rgdal::readOGR()`
#' so that character variables aren't converted to factors.
#'
#' @note the parameter `name` is temporarily not useable. MarineRegions
#' updated their web services, and we haven't sorted out yet how to make
#' this feature work. We may bring it back in future version of this pacakge.
#'
#' @examples \dontrun{
#' ## just get path
#' mr_shp(key = "MarineRegions:eez_iho_union_v2", read = FALSE)
#' ## read shp file into spatial object
#' res <- mr_shp(key = "MarineRegions:eez_iho_union_v2", read = TRUE)
#'
#' mr_shp(key = "SAIL:w_marinehabitatd")
#'
#' # maxFeatures
#' library(sp)
#' plot(mr_shp(key = "MarineRegions:eez_iho_union_v2"))
#' plot(mr_shp(key = "MarineRegions:eez_iho_union_v2", maxFeatures = 5))
#'
#' # vizualize with package leaflet
#' if (requireNamespace("leaflet")) {
#'   library('leaflet')
#'   leaflet() %>%
#'     addTiles() %>%
#'     addPolygons(data = res)
#' }
#'
#' # use `filter` param to get a subset of a region
#' library(sp)
#' pp <- mr_shp(key = "MarineRegions:eez_iho_union_v2")
#' plot(pp)
#' rr <- mr_shp(key = "MarineRegions:eez_iho_union_v2",
#'   filter = "North Atlantic Ocean")
#' plot(rr)
#'
#' # get Samoan Exclusive Economic Zone
#' res <- mr_shp(
#'   key = "MarineRegions:eez",
#'   filter = "Samoan Exclusive Economic Zone"
#' )
#' sp::plot(res)
#' }
mr_shp <- function(key = NULL, name = NULL, maxFeatures = 500,
                   overwrite = TRUE, read = TRUE, filter = NULL, ...) {

  if (!is.null(name)) {
    stop("'name' is not supported right now, hopefully return in next version",
         call. = FALSE)
  }
  cache_dir <- rappdirs::user_cache_dir("mregions")
  if (!file.exists(cache_dir)) dir.create(cache_dir, recursive = TRUE)

  args <- make_args('shp', name, key, maxFeatures)
  key <- nameorkey(name, key)

  file <- file.path(
    cache_dir,
    paste0(
      sub(":", "_", args$typeName),
      "_maxfeatures",
      if (is.null(args$maxFeatures)) "null" else args$maxFeatures,
      ".zip"
    )
  )
  if (!file.exists(sub("\\.zip", "", file))) {
    res <- m_GET(url = sub("ows", file.path(strsplit(key, ":")[[1]][1], "ows"),
                           vliz_base()),
                 args, file, overwrite, config = httr::verbose())
  } else {
    res <- path.expand(list.files(sub("\\.zip", "", file), pattern = ".shp",
                                  full.names = TRUE))
  }

  if (read) {
    check4pkg("rgdal")
    nm <- basename(sub("\\.zip", "", file))
    if (nm %in% ls(envir = mr_shp_env)) {
      # use cached version in an environment
      shp <- get(nm, envir = mr_shp_env)
    } else {
      # read from disk
      shp <- read_shp(res)
      assign(nm, shp, envir = mr_shp_env)
    }
    if (!is.null(filter)) {
      shp[shp$geoname == filter, ]
    } else {
      shp
    }
  } else {
    structure(res, class = 'mr_shp_file')
  }
}

read_shp <- function(x) {
  # rgdal::readOGR(x, rgdal::ogrListLayers(x), verbose = FALSE,
  #                stringsAsFactors = FALSE)
  sf::read_sf(x)
}

mr_shp_env <- new.env()