如何在R中绘制圆形地图投影并为乌拉圭区域添加矩形框

1. 加载所需R包 #

先安装并加载绘图和地图相关的包：

install.packages(c("ggplot2", "maps", "ggspatial")) # 首次运行需安装
library(ggplot2)
library(maps)
library(ggspatial)

2. 绘制带边界的基础世界地图 #

使用map_data("world")获取标准世界地图数据，通过geom_polygon的color参数添加国家/海岸线边界，解决“地球没有边界”的问题：

world_map <- map_data("world")

ggplot() +
  geom_polygon(data = world_map, aes(x = long, y = lat, group = group), 
               fill = "lightblue", color = "black", size = 0.2) +
  coord_fixed(ratio = 1.3) # 维持地图比例，避免拉伸变形

3. 添加乌拉圭区域的矩形框 #

乌拉圭的大致经纬度范围为：西经53°-58°（对应R中经度值-58到-53）、南纬30°-35°（对应R中纬度值-35到-30）。用geom_rect绘制醒目的标记框：

ggplot() +
  geom_polygon(data = world_map, aes(x = long, y = lat, group = group), 
               fill = "lightblue", color = "black", size = 0.2) +
  geom_rect(aes(xmin = -58, xmax = -53, ymin = -35, ymax = -30), 
            fill = NA, color = "red", size = 1.2) + # 空心红框突出目标区域
  coord_fixed(ratio = 1.3) +
  labs(title = "世界地图 - 乌拉圭区域标记", x = "经度", y = "纬度") +
  theme_bw() # 切换为简洁的白底主题

可选：放大聚焦乌拉圭区域 #

如果需要更清晰地展示乌拉圭周边，调整坐标范围即可：

ggplot() +
  geom_polygon(data = world_map, aes(x = long, y = lat, group = group), 
               fill = "lightblue", color = "black", size = 0.2) +
  geom_rect(aes(xmin = -58, xmax = -53, ymin = -35, ymax = -30), 
            fill = NA, color = "red", size = 1.2) +
  coord_fixed(ratio = 1.3, xlim = c(-65, -45), ylim = c(-40, -25)) + # 限定显示的经纬度范围
  labs(title = "乌拉圭区域标记", x = "经度", y = "纬度") +
  theme_bw()

内容的提问来源于stack exchange，提问作者Tina