在R中，我如何使用ggplot在欧洲地图上绘制项目的位置和它们的源？

install.packages("ggplot2")
install.packages("maps")
install.packages("mapdata")
library(ggplot2)
library(maps)
library(mapdata)

europe <- map_data("world", region = "europe")

projects <- data.frame(
  project = c("项目1", "项目2", "项目3"),
  latitude = c(52.5200, 48.8566, 41.9028),
  longitude = c(13.4050, 2.3522, 12.4964),
  source = c("源1", "源2", "源3")
)

ggplot() +
  geom_polygon(data = europe, aes(x = long, y = lat, group = group), fill = "lightgray") +
  geom_point(data = projects, aes(x = longitude, y = latitude, color = source), size = 3) +
  geom_text(data = projects, aes(x = longitude, y = latitude, label = project), vjust = -0.5) +
  coord_map() +
  labs(title = "欧洲项目位置和源") +
  theme_bw()