如何在R中的地图上显示一些点

Question

我在 R 中使用此代码来显示地图。

library(maps)
library(raster)
library(rgeos)
library(ggplot2)
library(dplyr)

# Iran map
iran <- getData("GADM", country = "Iran", level = 1)
mymap <- fortify(iran)
mymap$id <- as.integer(mymap$id)

dat <- data.frame(id = rownames(iran@data),
                  state = iran@data$NAME_1,
                  pr = c(530,-42,1673,75,206,544,1490,118,75,
                         40,105,191,111,810, 609,425,418,550, 40, 425, -54,-50,
                         16, 18, 133,425, -30, 241,63, 191,100)) %>% 
  mutate(color_province = case_when(pr <= 50 ~ 'green',
                                    pr > 150 ~ 'red',
                                    TRUE ~ 'yellow'))
dat$id <- as.integer(dat$id)

mydf <- inner_join(mymap, dat, by = "id")
centers <- data.frame(gCentroid(iran, byid = TRUE))
centers$state <- dat$state

ggplot() +
  geom_map(data = mydf,
           map = mymap,
           aes(map_id = id, group = group,
               x = long, y = lat,
               fill = as.factor(color_province))) +
  coord_map() +
  labs(x = "", y = "") +
  scale_fill_manual(values = c("green", "red", "yellow"),
                    name = "areas")

现在我想添加一些大小不同的点（城市）来显示人口，但我无法添加点。

# Cities
Khorasan <- c(60,35)
Kerman <- c(54,30)
Sistan <- c(61,27)

Cities <- rbind(Khorasan, Kerman, Sistan) %>% 
  as.data.frame()
colnames(Cities) <- c("ras","bal")

# Show the cities on the map
points(x=Cities$ras, y=Cities$bal, col="slateblue", cex=3, pch=20)

你能帮我吗，我怎样才能在地图上添加一些点并且这些点的大小显示它们的种群？

Answer 1

我建议使用geom_sf 来处理坐标数据的简单方法。有关更多功能，请参阅package sf。来自rnaturalearth的国家数据。

library(rnaturalearth)
library(ggplot2)

part <- ne_countries(country="Iran", returnclass="sf")

Vahdat_Park <- c(51.484655, 35.653493)
Khorasan <- c(60,35)
Kerman <- c(54,30)
Sistan <- c(61,27)

sites <- data.frame(Vahdat_Park, Khorasan, Kerman, Sistan)
sites <- cbind( longitude=stack(sites[1,]), latitude=stack(sites[2,]))
sites
  longitude.values longitude.ind latitude.values latitude.ind
1         51.48465   Vahdat_Park        35.65349  Vahdat_Park
2         60.00000      Khorasan        35.00000     Khorasan
3         54.00000        Kerman        30.00000       Kerman
4         61.00000        Sistan        27.00000       Sistan

ggplot(part) + 
  geom_sf() +
  geom_point(data=sites, 
    aes(x = longitude.values, y = latitude.values, col=latitude.ind))

# adding a connection from Vahdat_Park to Khorasan
line <- data.frame(x=c(51.48465, 60.00000 ), y=c(35.65349, 35.00000))

ggplot(part) + 
  geom_sf() +
  geom_point(data=sites, 
    aes(x = longitude.values, y = latitude.values, col=latitude.ind)) +
  geom_line(data=line, aes(x=x, y=y ) )