# load needed libraries
library(ggplot2)
library(maps)

# get the world map
world_map <- map_data("world")

# define a vector of countries to highlight
highlight_countries <- c("USA", "Canada", "UK", "Australia", "Brazil")

# filter the world map data for just the highlighted countries
highlighted_map <- subset(world_map, region %in% highlight_countries)

# plot the world with the highlighted countries
ggplot() +
  geom_map(
    data = world_map,
    map = world_map,
    mapping = aes(x = long, y = lat, map_id = region),
    color = "white",
    fill = "grey80",
    size = 0.2
  ) +
  geom_map(
    data = highlighted_map,
    map = world_map,
    mapping = aes(x = long, y = lat, map_id = region, fill = region),
    color = "white",
    size = 0.2
  ) +
  coord_fixed() +
  theme_void() +
  scale_fill_brewer(palette = "Set2", name = "Highlighted Countries") +
  labs(title = "Highlighted Countries on a World Map")