Import Boundary Data

Use available_jpmap_data() to see which boundary files jpmap can find.

library(jpmap)
available <- if (jpmap_build_full_vignettes) {
  available_jpmap_data()
} else {
  available_jpmap_data(data_dir = tempfile())
}
jpmap_has_boundary_data <- nrow(available) > 0
jpmap_has_okinawa_data <- any(available$year == 2024 & available$pref_code == "47")
available_summary <- available[c("year", "pref_code", "prefecture", "source")]
row.names(available_summary) <- NULL
available_summary
#> [1] year       pref_code  prefecture source    
#> <0 rows> (or 0-length row.names)

The package checks two locations:

GeoPackage files installed by the companion jpmapdata package;
files saved in jpmap_data_dir(), unless you pass a custom data_dir.

Load Prefecture Data

jp_map() returns an sf object. Without extra options, prefecture maps use the first available all-Japan prefecture file.

prefectures <- jp_map("prefecture")
prefectures

Load Okinawa Municipal Data

The companion data package can provide official MLIT N03 municipal boundaries for Okinawa Prefecture as of January 1, 2024.

okinawa_municipalities <- jp_map("municipality", include = "Okinawa")
okinawa_municipalities

This works without data_year or data_dir when jpmap can see the Okinawa file through jpmapdata or jpmap_data_dir().

Load Locally Built Municipal Data

After building a local file, use the same include value to select the prefecture.

jpmap_build_data(year = 2024, prefecture = "Ehime")
ehime_municipalities <- jp_map("municipality", include = "Ehime", data_year = 2024)

If you saved the file somewhere else, pass that folder as data_dir.

ehime_municipalities <- jp_map(
  "municipality",
  include = "Ehime",
  data_year = 2024,
  data_dir = "jpmap-data"
)

Inspect A GeoPackage

The GeoPackage layers are ordinary spatial data layers, so you can inspect them with sf.

okinawa_file <- available$path[available$year == 2024 & available$pref_code == "47"]

sf::st_layers(okinawa_file)

Read a layer directly only when you need lower-level control. Most map workflows can use jp_map() instead.

municipalities <- sf::st_read(okinawa_file, layer = "municipalities")

File Names

jpmap recognizes these file names:

jpmap_boundaries_YYYY.gpkg for national data;
jpmap_boundaries_YYYY_PP.gpkg for one-prefecture data.

The PP suffix is the two-digit prefecture code, such as 38 for Ehime and 47 for Okinawa.