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Plot China Map with Customizable Options

Source: R/geom_mapcn.R
geom_mapcn.Rd

geom_mapcn provides a flexible interface for visualizing China's administrative boundaries. Users can select administrative levels (province, city, or county), apply custom projections, and filter specific regions.

Usage

geom_mapcn(
  data = NULL,
  admin_level = "province",
  crs = "+proj=aeqd +lat_0=35 +lon_0=105 +ellps=WGS84 +units=m +no_defs",
  color = "black",
  fill = "white",
  linewidth = 0.5,
  filter_attribute = NULL,
  filter = NULL,
  ...
)

Arguments

data

An sf object containing China's map data. If NULL, the function loads the package's default map. Users can select provincial, municipal, or county-level maps using the admin_level parameter.

admin_level

A character string specifying the administrative level of the map. Options are "province" (default), "city", or "county". The corresponding GeoJSON files (China_sheng.geojson, China_shi.geojson, China_xian.geojson) must be located in the package's extdata folder.

crs

Coordinate Reference System (CRS). Defaults to "+proj=aeqd +lat_0=35 +lon_0=105 +ellps=WGS84 +units=m +no_defs". Users can specify other CRS strings (e.g., "EPSG:4326").

color

Border color. Default is "black".

fill

Fill color. Default is "white".

linewidth

Line width for borders. Default is 0.5.

filter_attribute

Column name for filtering regions (e.g., "name_en").

filter

Character vector of values to filter specific regions (e.g., c("Beijing", "Shanghai")).

...

Additional parameters passed to geom_sf.

Value

A ggplot2 layer for visualizing China's administrative boundaries.

Examples

# Plot provincial map
ggplot() +
  geom_mapcn() +
  theme_minimal()


# Filter specific provinces
ggplot() +
  geom_mapcn(filter_attribute = "name_en", filter = c("Beijing", "Shanghai"), fill = "red") +
  theme_minimal()


# Use a Mercator projection
ggplot() +
  geom_mapcn(crs = "+proj=merc", linewidth = 0.7) +
  theme_minimal()