Modern maps with sf & projections

An equal-area, projected choropleth

world_data(2020, c(gdp = "NY.GDP.PCAP.KD"), geometry = "sf") |>
  world_map(gdp, style = "quantile", projection = "equal_earth",
            title = "GDP per capita (Equal Earth projection)")

world_map() auto-detects the sf backend and applies the projection through ggplot2::coord_sf(). Available projections are "equal_earth" (the default — equal-area and good-looking), "robinson", "mollweide", "natural_earth", "plate_carree", "mercator", "winkel_tripel", "eckert4", "gall_peters", "orthographic", "azimuthal_equal_area", "north_polar" and "south_polar".

The world as a globe

globe_map() draws an orthographic globe centred on lon/lat. The default "sf" backend gives the cleanest limb; the "polygon" backend below needs only maps + mapproj (no sf):

globe_map(world_snapshot$countries, continent, backend = "polygon",
          style = "categorical", lon = 10, lat = 20)

# With the sf backend (smoother limb, real great circles):
world_data(2020, geometry = "sf") |>
  globe_map(gdp_per_capita, lon = 10, lat = 30)

spin_globe() turns that into a rotating animation — one globe_map() frame per central longitude, assembled into a looping GIF with gifski (or magick):

spin_globe(world_snapshot$countries, continent, backend = "polygon",
           style = "categorical", n_frames = 60)

Just the canvas

world_geometry() returns projected, region-subset, antimeridian-safe geometry without any data — country polygons, label-ready centroids, coastlines, a graticule or an ocean rectangle:

africa <- world_geometry("countries", geometry = "sf", region = "Africa",
                         projection = "equal_earth")
ggplot(africa) +
  geom_sf(fill = "grey85", colour = "grey40", linewidth = 0.1) +
  theme_world_map()

The live sf map is not shown because sf is not installed in this build.

Recentring and the antimeridian

A Pacific-centred world is one argument away; the sf pipeline runs sf::st_break_antimeridian() before projecting, so nothing streaks across the frame:

world_geometry("countries", geometry = "sf", recenter = 150)

Region subsetting

region accepts a continent, a group name ("EU", "OECD", …), a vector of iso3c codes, or a bounding box c(xmin, ymin, xmax, ymax). Pair it with a projection suited to the subset (e.g. "azimuthal_equal_area" for a single continent, the polar projections for the Arctic) so the crop stays area-honest.

A box is the one form that clips the shapes themselves, which is what you want for a region that is neither a continent nor a group — the Mediterranean basin, say. Use the sf backend for it: that clip is a real sf::st_crop(), whereas the polygon backend can only drop the vertices outside the box and warns that a country crossing the edge comes back with an approximate outline.

med <- world_geometry("countries", geometry = "sf",
                      region = c(-10, 30, 40, 48), projection = "equal_earth")
ggplot(med) +
  geom_sf(fill = "grey85", colour = "grey40", linewidth = 0.1) +
  theme_world_map()

Simplifying for the web

High-resolution geometry can be thinned for fast plotting with simplify_geometry() (which uses rmapshaper when available). scale = "medium" is the 50m Natural Earth data; "large" is 10m and additionally needs the rnaturalearthhires package, which is not on CRAN.

world_geometry(geometry = "sf", scale = "medium") |>
  simplify_geometry(keep = 0.1)