在R中画地图先从简单的maps包开始。

library("maps")

在这个maps包中有一些数据集，用命令data(package=”maps”)，可以看到如下数据：

canada.cities          Database of Canadian cities
county.fips            FIPS county codes for US County Map
countyMapEnv           United States County Map
franceMapEnv           France Map
italyMapEnv            Italy Map
nzMapEnv               New Zealand Basic Map
ozone                  Sample datasets
state.carto.center     United States State Population Cartogram Map
state.cartoMapEnv      United States State Population Cartogram Map
state.fips             FIPS state codes for US 48 State Map
state.vbm.center       United States State Visibility Base Map
state.vbmMapEnv        United States State Visibility Base Map
stateMapEnv            United States State Boundaries Map
unemp                  Sample datasets
us.cities              Database of US cities
usaMapEnv              United States Coast Map
votes.repub            Sample datasets
world.cities           Database of world cities
world2MapEnv           Pacific Centric Low resolution World Map
worldMapEnv            Low resolution World Map

画出美国各州的边界：

map(\'state\', panel.first=grid())

axis(1,lwd=0)

axis(2,lwd=0)

axis(3,lwd=0)

axis(4,lwd=0)

box()

标出美国的城市：

data(us.cities)

points(us.cities$long, us.cities$lat, pch=19)

标出人口大于一百万的城市

cities <- us.cities[us.cities$pop > 1000000,]

points(cities$long, cities$lat, pch=19)

text(cities$long, cities$lat, cities$name, col="blue", cex=0.8, pos=1)