我尝试了以下代码:
library(ggplot2)
library(ggmap)
library(sf)
nc <- st_read(system.file("shape/nc.shp", package = "sf"))
str(nc)
Classes ‘sf’ and 'data.frame': 100 obs. of 15 variables:
$ AREA : num 0.114 0.061 0.143 0.07 0.153 0.097 0.062 0.091 0.118 0.124 ...
$ PERIMETER: num 1.44 1.23 1.63 2.97 2.21 ...
$ CNTY_ : num 1825 1827 1828 1831 1832 ...
$ CNTY_ID : num 1825 1827 1828 1831 1832 ...
$ NAME : Factor w/ 100 levels "Alamance","Alexander",..: 5 3 86 27 66 46 15 37 …