ggplot2在同一张地图上用一种颜色映射县界,用另一种颜色映射州界 [英] ggplot2 mapping county boundries in one color and state boundries in another on the same map
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问题描述
我正在创建带有灰色边框的Choropleth县地图,并且我还希望将州边界设为黑色.有谁知道我要如何在现有的县地图上添加第二层州地图?
I am creating a choropleth county map with grey borders, and I also want to include the state boundries in black. Does anyone know how I go about adding a second layer of state mapping to an existing county map?
Here's the data set and code I ended up using:
#load libraries
library(ggplot2)
library(ggmap)
library(maps)
library(plyr)
#get wif file
wip <- read.csv("wip.csv")
#get map data for US counties and states
county_map <- map_data("county")
state_map <- map_data("state")
#merge wip and county_map
wip_map <- merge(county_map, wip, by.x=c("region", "subregion"),
by.y=c("region","subregion"), all.x=TRUE)
#resort merged data
wip_map <- arrange(wip_map, group, order)
#relpace NA with 0's
wip_map[is.na(wip_map)] <- 0
#generate a disctrete color pallette
pal <- c("#F7FCF5","#74C476","#41AB5D","#238B45","#006D2C","#00441B")
theme_clean <- function(base_size = 12) {
require(grid)
theme_grey(base_size) %+replace%
theme(
axis.title = element_blank(),
axis.text = element_blank(),
panel.background = element_blank(),
panel.grid = element_blank(),
axis.ticks.length = unit(0,"cm"),
axis.ticks.margin = unit(0,"cm"),
panel.margin = unit(0,"lines"),
plot.margin = unit(c(0,0,0,0),"lines"),
complete = TRUE
)
}
final_map <- ggplot(wip_map, aes(x=long, y=lat, group=group, fill=factor(CATEGORY))) +
geom_polygon(colour="grey", aes(fill=factor(CATEGORY))) +
scale_fill_manual(values=pal) +
expand_limits(x = wip_map$long, y = wip_map$lat) +
coord_map("polyconic") +
labs(fill="Number Per\nCounty") +
theme_clean()
final_map + geom_path( data = state_map , colour = "red")
谢谢!
推荐答案
只需在您的代码中添加 geom_path
...
Just add a geom_path
to your code...
我用红色突出显示了边界,但您可以轻松地将其设置为黑色.
I used red to highlight the boundaries but you can easily just set it to black.
ggplot( wip_map, aes( x = long , y = lat , group=group ) ) +
geom_polygon( colour = "grey" , aes( fill = factor( CATEGORY ) ) ) +
scale_fill_manual( values = pal ) +
expand_limits( x = wip_map$long, y = wip_map$lat ) +
coord_map( "polyconic" ) +
labs(fill="Number Per\nCounty") +
theme_clean( ) +
geom_path( data = state_map , colour = "red")
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