Points

Cropped Grid of Points on World Map

library(ggplot2)
library(sf)
library(rnaturalearth)
library(rnaturalearthdata)

# Load the world map as an sf object
world <- ne_countries(scale = "medium", returnclass = "sf") 
# Define the resolution of the grid (e.g., 5 degrees)
resolution <- 3

# Create a grid of longitude and latitude points
grid <- expand.grid(lon = seq(-180, 180, by = resolution), 
                    lat = seq(-90, 90, by = resolution))

# Convert the grid to an sf object
grid_sf <- st_as_sf(grid, coords = c("lon", "lat"), crs = 4326)

# It takes long time to run
# Crop the grid points so that only points within the world map polygons remain
grid_cropped <- st_intersection(grid_sf, world)

library(ggthemes)
library(ggspatial)
# Plot
map <- ggplot() +
  geom_sf(data = grid_cropped, 
          linetype = "dotdash",
          shape = 21, 
          stroke = 0.2, 
          fill = NA) +
  geom_sf(data = grid_cropped, 
          aes(color = sovereignt), 
          show.legend = F,
          size = 0.3) +
  scale_color_viridis_d(option = "F", 
                        begin = 0.1, 
                        end = 0.9) + # Adjusts color gradient for better contrast
  coord_sf(crs = sf::st_crs("+proj=robin")) +
  ggthemes::theme_map() 
map

map + 
  # add a north arrow
  ggspatial::annotation_north_arrow(location = "br") +
  # add a title and a caption
  labs(title = "Cropped Grid of Points on World Map",
       caption = "Source: Natural Earth | #30DayMapChallenge 2024 Day1 | @fgazzelloni") +
  # adjust the appearance of the plot
  theme(text = element_text(family = "Courier"),
        plot.title = element_text(size = 16, color = "grey20", face = "bold"),
        plot.caption = element_text(size = 8, color = "grey20", face = "bold"),
        plot.background = element_rect(fill = NA, color = NA),
        panel.background = element_rect(fill = NA, color = NA),
        #panel.grid = element_line(color = "grey90"),
        legend.position = "none")