# 将数据框转换为sf对象 cities_sf <- st_as_sf(cities, coords = c("lon", "lat"), crs = 4326) # 查看原始坐标系统 print(crs(cities_sf)) # 转换坐标系统为WGS 84 cities_sf_wgs84 <- st_transform(cities_sf, crs = st_crs(4326)) # 查看转换后的坐标系统 print(crs(cities_sf_wgs84)...