Adding_Basic_Map

library(ggmapcn)
#> Loading required package: ggplot2

Introduction

The ggmapcn package provides various tools for visualizing geographic data in China and beyond. This vignette demonstrates the basic and advanced usage of geom_mapcn() and geom_world() for plotting administrative boundaries and combining geographic data.

Example 1: Basic Map of China

To plot a map of China with province boundaries, use the geom_mapcn() function. The map uses the Azimuthal Equal Distance projection by default.

ggplot() +
  geom_mapcn() +
  theme_minimal()

Example 2: Adding Buffer Zones and Coastlines

Here’s a comprehensive example demonstrating how to plot province boundaries, buffer zones, and coastlines on the same map:

ggplot() +
  geom_buffer_cn(mainland_dist = 40000) +
  geom_buffer_cn(mainland_dist = 20000, fill = "#BBB3D8") +
  geom_mapcn(fill = "white") +
  geom_boundary_cn() +
  theme_bw()

Example 3: Overlaying China on a World Map

The geom_world() function allows you to visualize global data, while geom_mapcn() overlays China for detailed analysis.

# Define projections
china_proj <- "+proj=aeqd +lat_0=35 +lon_0=105 +ellps=WGS84 +units=m +no_defs"

# Combine world map as a background and China map as overlay
ggplot() +
  # World map as background
  geom_world(fill = "gray90", color = "gray70", linewidth = 0.2) +
  coord_proj(
    crs = "+proj=merc",
    xlim = c(-180, 180),
    ylim = c(-90, 90)
  ) +
  # Overlay China map
  geom_mapcn(
    fill = "lightblue",
    color = "black",
    linewidth = 0.5
  ) +
  geom_boundary_cn(color = "red", linewidth = 0.6) +
  theme_minimal()
#> Linking to GEOS 3.11.2, GDAL 3.8.2, PROJ 9.3.1; sf_use_s2() is TRUE
#> Coordinate system already present. Adding new coordinate system, which will
#> replace the existing one.
#> Warning: Duplicated aesthetics after name standardisation: colour and linewidth
#> Duplicated aesthetics after name standardisation: colour and linewidth
#> Duplicated aesthetics after name standardisation: colour and linewidth
#> Duplicated aesthetics after name standardisation: colour and linewidth
#> Duplicated aesthetics after name standardisation: colour and linewidth

Example 3: Filtering China and Its Neighbors

This example demonstrates filtering for China and its neighboring countries, highlighting China in red.

# Define neighboring countries
china_neighbors <- c("CHN", "AFG", "BTN", "MMR", "LAO", "NPL", "PRK", "KOR",
                     "KAZ", "KGZ", "MNG", "IND", "BGD", "TJK", "PAK", "LKA", "VNM")

# Plot world map with filtered countries
ggplot() +
  geom_world(fill = "gray90", color = "gray70", linewidth = 0.2) +
  geom_world(
    filter = china_neighbors,
    filter_attribute = "SOC",
    fill = "lightblue",
    color = "black",
    linewidth = 0.5
  ) +
  geom_world(
    filter = "CHN",
    filter_attribute = "SOC",
    fill = "red",
    color = "black",
    linewidth = 0.8
  ) +
  coord_proj(
    crs = "+proj=merc",
    xlim = c(60, 140),
    ylim = c(-10, 60)
  ) +
  theme_minimal()