Interactive Web Maps with leaflet

plot_jpmap() is the right tool for static maps with Okinawa and Ogasawara insets. Leaflet is different: web tiles expect true longitude and latitude, so jp_map_leaflet() uses literal WGS84 geography rather than the inset layout.

Install leaflet before running these examples:

install.packages("leaflet")

Prefecture Choropleth

library(tidyverse)
library(jpmap)

gdp <- jp_prefecture_gdp |>
  select(pref_code, prefecture, gdp_per_capita_jpy)

jp_map_leaflet(
  "prefecture",
  data = gdp,
  values = "gdp_per_capita_jpy",
  palette = "Blues",
  popup = "prefecture",
  simplify_tolerance = 0.03
)

jp_map_leaflet() uses the same data-join logic as plot_jpmap(). If your data has numeric prefecture codes such as 1, 2, and 47, jpmap can still match them to map codes such as "01", "02", and "47".

Disputed-Territory Layer

For web maps, use territorial_disputes = FALSE to exclude disputed-territory shapes, or highlight them explicitly.

jp_map_leaflet(
  "prefecture",
  fill = "grey92",
  disputed_fill = "#005BAC",
  disputed_color = "#001040",
  disputed_dots = TRUE
)

Small disputed-territory polygons can be hard to click at a national zoom level, so disputed_dots = TRUE can add circle markers when you choose to emphasize them.

Municipal Map

Okinawa municipal data can be used when the corresponding boundary file is available through jpmapdata or jpmap_data_dir().

jp_map_leaflet(
  "municipality",
  include = "Okinawa",
  fill = "grey92",
  color = "white",
  weight = 0.8,
  popup = "municipality_ja"
)

For other prefectures or nationwide municipal maps, build local MLIT N03 data first with jpmap_build_data().

Quarto, pkgdown, And Shiny

Leaflet widgets returned by jp_map_leaflet() are ordinary htmlwidgets. You can place them directly in Quarto documents, pkgdown articles, R Markdown reports, and Shiny UI outputs.

For Shiny, build the widget inside renderLeaflet():

output$japan_map <- leaflet::renderLeaflet({
  jp_map_leaflet(
    "prefecture",
    data = jp_prefecture_gdp,
    values = "gdp_per_capita_jpy"
  )
})

Use plot_jpmap() when the map needs the compact inset layout. Use jp_map_leaflet() when users need pan, zoom, labels, popups, and website interaction.