In nmcdev/nmcMetResources: Data Resources for Meteorological Packages.

Extract the coordinates from the the shape files into a data frame and plot lines for speed up the plotting of polygons in r (the first method) [http://gis.stackexchange.com/questions/62292/how-to-speed-up-the-plotting-of-polygons-in-r].

# Convert the polygons into data frames so we can make lines.
# Extract the coordinates from the shape files to get the
#   longitude and latitudes of the polygons. Then we can
#   put them into a data frame with the first column containing
#   the longitudes and the second column containing latitudes.
#   The different shapes are separated by NAs.
poly2df <- function(poly) {
  # Number of regions
  n_regions <- length(poly@polygons)

  # Get the coords into a data frame
  poly_df <- c()
  for(i in 1:n_regions) {

    # Number of polygons for first region
    n_poly <- length(poly@polygons[[i]]@Polygons)
    print(paste("There are",n_poly,"polygons"))

    # Create progress bar
    # pb <- txtProgressBar(min = 0, max = n_poly, style = 3)
    for(j in 1:n_poly) {
      poly_df <- rbind(poly_df, NA,
                       poly@polygons[[i]]@Polygons[[j]]@coords)
      # Update progress bar
      # setTxtProgressBar(pb, j)
    }
    #close(pb)
    print(paste("Finished region",i,"of",n_regions))
  }
  poly_df <- data.frame(poly_df)
  names(poly_df) <- c('lon','lat')
  return(poly_df)
}

#
# convert the China nation, province, county and river boundary to dataframe.

# national boundary
nationDF <- rgdal::readOGR(usethis::proj_path("inst", "extdata"), "bou1_4p")
nationGDF <- ggplot2::fortify(nationDF)
nationDF <- poly2df(nationDF)
usethis::use_data(nationGDF, overwrite = TRUE)
usethis::use_data(nationDF, overwrite = TRUE)

# province boundary
provinceDF <- rgdal::readOGR(usethis::proj_path("inst", "extdata"), "bou2_4p")
provinceGDF <- ggplot2::fortify(provinceDF)
provinceDF <- poly2df(provinceDF)
usethis::use_data(provinceGDF, overwrite = TRUE)
usethis::use_data(provinceDF, overwrite = TRUE)

# county boundary
countyDF <- rgdal::readOGR(usethis::proj_path("inst", "extdata"), "BOUNT_poly")
countyGDF <- ggplot2::fortify(countyDF)
countyDF <- poly2df(countyDF)
usethis::use_data(countyGDF, overwrite = TRUE)
usethis::use_data(countyDF, overwrite = TRUE)

# river 1st class boundary
river1DF <- rgdal::readOGR(usethis::proj_path("inst", "extdata"), "hyd1_4p")
river1GDF <- ggplot2::fortify(river1DF)
river1DF <- poly2df(river1DF)
usethis::use_data(river1GDF, overwrite = TRUE)
usethis::use_data(river1DF, overwrite = TRUE)

# river 2nd class boundary
river2DF <- rgdal::readOGR(usethis::proj_path("inst", "extdata"), "hyd2_4p")
river2GDF <- ggplot2::fortify(river2DF)
river2DF <- poly2df(river2DF)
usethis::use_data(river2GDF, overwrite = TRUE)
usethis::use_data(river2DF, overwrite = TRUE)