Adding decimal coordinates to a map with ggplot2 and GADM data-CodePudding

I'm trying to plot a map of France and then show where Paris is.

So with the code below, I can plot a map of France.

library(dplyr) 
library(ggplot2) 
library(ggsn) 
library(here) 
library(readr) 
library(sf) 
u_remote <- "https://biogeo.ucdavis.edu/"
p_remote <- "data/gadm3.6/Rsf/"
f_name <- "gadm36_FRA_1_sf.rds"

fr_rds <- file.path(tempdir(), "gadm36_FRA_1_sf.rds")

if (toupper(Sys.info()["sysname"]) == "WINDOWS") {
  download.file(
    url = paste0(u_remote, p_remote, f_name),
    destfile = fr_rds,
    method = "wininet",
    mode = "wb"
  )
} else {
  download.file(
    url = paste0(u_remote, p_remote, f_name),
    destfile = fr_rds,
    method = "auto"
  )
}

fr_sf <- readRDS(fr_rds)

ggplot(fr_sf)   
  geom_sf(fill = "white")

I also got the coordinates of a point in Paris from Google Maps so I thought maybe this works

paris <- data.frame(longitude = c(48.86122650866868), latitude = c(2.341541835915652))

ggplot(fr_sf)   
  geom_sf(fill = "white")   
  geom_point(data = paris, aes(x = longitude, y = latitude), size = 4, shape = 23, fill = "darkred")

But I think ggplot converts axis to degrees.

Could someone help with this please?

CodePudding user response：

I think you have simply mixed up latitude and longitude:

paris <- data.frame(latitude = c(48.86122650866868), 
                    longitude = c(2.341541835915652))

ggplot(fr_sf)   
  geom_sf(fill = "white")   
  geom_point(data = paris, aes(x = longitude, y = latitude), size = 4, 
             shape = 23, fill = "darkred")