Question

如何在美国单独绘制某些州并标记它们？

目前我已经能够使用此功能绘制状态

library(maps)
map("state",c('New York','massachusetts','Pennsylvania'),fill=TRUE,col="dark green",projection="polyconic")

但我还没有给它们贴上标签。

Answer 1

您可以使用ggmap和ggplot2包在美国地图中绘制美国州。

library(ggmap)
library(ggplot2)
usaState<- data.frame(c("new york", "massachusetts", "pennsylvania"))
colnames(usaState) <- "statename"
LatLon <-  c(apply(usaState, 1, geocode))
LatLonDF <- do.call(rbind.data.frame, LatLon)
stateLatLonDF <- cbind(usaState, LatLonDF)
myMap <- ggmap(get_map(location = 'united states', zoom = 4, source = 'google', maptype="terrain"))
myMap <- myMap + geom_text(data = stateLatLonDF, aes(x = lon, y = lat, label = statename), size = 3, vjust = 0, hjust = -0.1, color = "red")
print(myMap)

可以根据需要更改缩放，文本参数等。希望这会有所帮助。

Answer 2

@Gughan在前面的代码片段中，我使用了get_map（location =＆＃39;美国＆＃39;）来获取地图，这将带来整个美国地图。要放大到特定位置，可以通过纬度和经度的平均值获得get_map（）的位置。通过控制get_map（）中的缩放参数，并运行以下代码，我将东海岸放大。

library(ggmap)
library(ggplot2)
usaState<- data.frame(c("new york", "massachusetts", "pennsylvania"))
colnames(usaState) <- "statename"
LatLon <-  c(apply(usaState, 1, geocode))
LatLonDF <- do.call(rbind.data.frame, LatLon)
stateLatLonDF <- cbind(usaState, LatLonDF)
map <- get_map(location = c(lon = mean(stateLatLonDF$lon), lat = mean(stateLatLonDF$lat)), color="color",source="google", maptype="terrain", zoom=7)
ggmap(map) + geom_point(data = stateLatLonDF, aes(x = lon, y = lat, color = statename, alpha = 0.5, fill = "red"), size = 5, shape = 21) + geom_text(data = stateLatLonDF, aes(x = lon, y = lat, label = statename), size = 3, vjust = 0, hjust = -0.1, color = "blue") + scale_colour_discrete(name  = "statename")

在R中绘制美国地图

2 个答案: