R/convertTMWorldBorders.R

In MazamaSpatialUtils: Spatial Data Download and Utility Functions

#' @importFrom rlang .data
#' @export
#'
#' @title Convert world borders shapefile
#'
#' @description Returns a simple features data frame for world divisions
#'
#' The full resolution file will be named "TMWorldBorders.rda". In addition,
#' "_05", _02" and "_01" versions of the file will be created that that are
#' simplified to 5\%, 2\% and 1\%. Simplified versions will greatly improve the
#' speed of both searching and plotting.
#'
#' @details A world borders shapefile is downloaded and converted to a
#' simple features data frame with additional columns of data. The resulting file is
#' created in the spatial data directory which is set with \code{setSpatialDataDir()}.
#'
#' @return Name of the datasetName being created.
#'
#' @references \url{https://thematicmapping.org/}
#'

convertTMWorldBorders <- function() {

  # ----- Setup ----------------------------------------------------------------

  # Use package internal data directory
  dataDir <- getSpatialDataDir()

  # Specify the name of the dataset and file being created
  datasetName <- 'TMWorldBorders'

  # ----- Get the data ---------------------------------------------------------

  # Build appropriate request URL for TM World Borders data
  url <- "http://thematicmapping.org/downloads/TM_WORLD_BORDERS-0.3.zip"

  filePath <- file.path(dataDir, basename(url))
  utils::download.file(url, filePath)
  # NOTE:  This zip file has no directory so extra subdirectory needs to be created
  utils::unzip(filePath, exdir = file.path(dataDir, 'world'))

  # ----- Convert to SFDF ------------------------------------------------------

  # Convert shapefile into simple features data frame
  # NOTE:  The 'world' directory has been created
  dsnPath <- file.path(dataDir, 'world')
  shpName <- 'TM_WORLD_BORDERS-0.3'
  SFDF <- convertLayer(
    dsn = dsnPath,
    layer = shpName
  )

  # ----- Select useful columns and rename -------------------------------------

  # > dplyr::glimpse(SFDF, width = 75)
  # Rows: 246
  # Columns: 12
  # $ FIPS      <chr> "AC", "AG", "AJ", "AL", "AM", "AO", "AQ", "AR", "AS", "…
  # $ ISO2      <chr> "AG", "DZ", "AZ", "AL", "AM", "AO", "AS", "AR", "AU", "…
  # $ ISO3      <chr> "ATG", "DZA", "AZE", "ALB", "ARM", "AGO", "ASM", "ARG",…
  # $ UN        <int> 28, 12, 31, 8, 51, 24, 16, 32, 36, 48, 52, 60, 44, 50, …
  # $ NAME      <chr> "Antigua and Barbuda", "Algeria", "Azerbaijan", "Albani…
  # $ AREA      <int> 44, 238174, 8260, 2740, 2820, 124670, 20, 273669, 76823…
  # $ POP2005   <dbl> 83039, 32854159, 8352021, 3153731, 3017661, 16095214, 6…
  # $ REGION    <int> 19, 2, 142, 150, 142, 2, 9, 19, 9, 142, 19, 19, 19, 142…
  # $ SUBREGION <int> 29, 15, 145, 39, 145, 17, 61, 5, 53, 145, 29, 21, 29, 3…
  # $ LON       <dbl> -61.783, 2.632, 47.395, 20.068, 44.563, 17.544, -170.73…
  # $ LAT       <dbl> 17.078, 28.163, 40.430, 41.143, 40.534, -12.296, -14.31…
  # $ geometry  <MULTIPOLYGON [°]> MULTIPOLYGON (((-61.68667 1..., MULTIPOLYG…

  # Data Dictionary:
  #   FIPS ------> FIPS: 2-digit FIPS code
  #   ISO2 ------> countryCode
  #   ISO3 ------> ISO3
  #   UN --------> UN_country
  #   NAME ------> countryName
  #   AREA ------> area
  #   POP2005 ---> population2005
  #   REGION ----> UN_region
  #   SUBREGION -> UN_subregion
  #   LON -------> longitude
  #   LAT -------> latitude


  # Create the new dataframe in a specific column order
  SFDF <-
    SFDF %>%
    dplyr::select(
      FIPS = .data$FIPS,
      countryCode = .data$ISO2,
      ISO3 = .data$ISO3,
      UN_country = .data$UN,
      countryName = .data$NAME,
      area = .data$AREA,
      population2005 = .data$POP2005,
      UN_region = .data$REGION,
      UN_subregion = .data$SUBREGION,
      longitude = .data$LON,
      latitude = .data$LAT
    )

  # TODO:  Is this iconv() step still necessary now that we're using *sf*
  # NOTE:  http://conjugateprior.org/2013/01/unicode-in-r-packages-not/
  # Transliterate unicode characters for this package-internal datasetName
  SFDF$countryName <- iconv(SFDF$countryName, from = "UTF-8", to = "ASCII//TRANSLIT")

  # Rationalize units: convert area from units of 10 km^2 to m^2
  SFDF$area <- SFDF$area * 1e7

  # ----- Simplify and save ----------------------------------------------------

  uniqueIdentifier <- "countryCode"

  simplifyAndSave(
    SFDF = SFDF,
    datasetName = datasetName,
    uniqueIdentifier = uniqueIdentifier,
    dataDir = dataDir
  )

  # ----- Clean up and return --------------------------------------------------

  # Clean up
  unlink(filePath, force = TRUE)
  unlink(dsnPath, recursive = TRUE, force = TRUE)

  return(invisible(datasetName))

}

# ===== TEST ===================================================================

if ( FALSE ) {

  library(sf)

  # Look or horizontal lines from polygons that cross the dateline.
  # NOTE:  These are sometimes created by sf::st_make_valid()
  loadSpatialData(datasetName)
  SFDF <- get(paste0(datasetName, ""))
  SFDF_05 <- get(paste0(datasetName, "_05"))
  SFDF_02 <- get(paste0(datasetName, "_02"))
  SFDF_01 <- get(paste0(datasetName, "_01"))

  plot(SFDF_01$geometry)
  dev.off(dev.list()["RStudioGD"])
  plot(SFDF_02$geometry)
  dev.off(dev.list()["RStudioGD"])
  plot(SFDF_05$geometry)
  dev.off(dev.list()["RStudioGD"])
  #plot(SFDF$geometry)

  # Try out getSpatialData()
  lons <- c(-120:-110, 0:10)
  lats <- c(30:40, 30:40)

  df <- getSpatialData(lons, lats, SFDF_01)
  df <- getSpatialData(lons, lats, SFDF_02)
  df <- getSpatialData(lons, lats, SFDF_05)
  df <- getSpatialData(lons, lats, SFDF)

  # Special Case of Russian failing to plot properly
  SFDF %>% dplyr::filter(countryCode == "RU") %>% sf::st_geometry() %>% plot()

}