繪制（填充顏色）地圖與美國陳述R中的數據

Question

我有以下數據，我想在美國的州地圖上繪制：

x = data.frame(state.x77[,"Income"])

如何在地圖上將這些顏色填充為狀態？

我可以繪制地圖：

map("state", boundary=TRUE, col=colorRampPalette(c("blue","green","yellow","red"))(50), fill=T)

我可以匹配各州：

match(map("state",plot=F)$names, tolower(rownames(x)))

我試圖從？map_data修改示例：

if (require("maps")) {
states <- map_data("state")
arrests <- USArrests
names(arrests) <- tolower(names(arrests))
arrests$region <- tolower(rownames(USArrests))

choro <- merge(states, arrests, sort = FALSE, by = "region")
choro <- choro[order(choro$order), ]
qplot(long, lat, data = choro, group = group, fill = assault,
  geom = "polygon")
qplot(long, lat, data = choro, group = group, fill = assault / murder,
  geom = "polygon")
}

但我無法調整它。 謝謝你的幫助。

Answer 1

您無需將逮捕數據與地圖數據合並。 您可以將地圖數據單獨傳遞到geom_map圖層。 嘗試

x = data.frame(region=tolower(rownames(state.x77)), 
    income=state.x77[,"Income"], 
    stringsAsFactors=F)

states_map <- map_data("state")
ggplot(x, aes(map_id = region)) + 
    geom_map(aes(fill = income), map = states_map) +
    scale_fill_gradientn(colours=c("blue","green","yellow","red")) + 
    expand_limits(x = states_map$long, y = states_map$lat)