Map projections.

Usage

coord_map(projection = "mercator", ..., orientation = NULL, xlim = NULL, ylim = NULL)

Arguments

projection
projection to use, see mapproject for list
...
other arguments passed on to mapproject
orientation
projection orientation, which defaults to c(90, 0, mean(range(x))). This is not optimal for many projections, so you will have to supply your own. See mapproject for more information.
xlim
manually specific x limits (in degrees of lontitude)
ylim
manually specific y limits (in degrees of latitude)

Description

This coordinate system provides the full range of map projections available in the mapproj package.

Details

This is still experimental, and if you have any advice to offer regarding a better (or more correct) way to do this, please let me know

Examples

if (require("maps")) { # Create a lat-long dataframe from the maps package nz <- map_data("nz") nzmap <- ggplot(nz, aes(x=long, y=lat, group=group)) + geom_polygon(fill="white", colour="black") # Use cartesian coordinates nzmap # With default mercator projection nzmap + coord_map() # Other projections nzmap + coord_map("cylindrical") nzmap + coord_map("azequalarea",orientation=c(-36.92,174.6,0)) states <- map_data("state") usamap <- ggplot(states, aes(x=long, y=lat, group=group)) + geom_polygon(fill="white", colour="black") # Use cartesian coordinates usamap # With mercator projection usamap + coord_map() # See ?mapproject for coordinate systems and their parameters usamap + coord_map("gilbert") usamap + coord_map("lagrange") # For most projections, you'll need to set the orientation yourself # as the automatic selection done by mapproject is not available to # ggplot usamap + coord_map("orthographic") usamap + coord_map("stereographic") usamap + coord_map("conic", lat0 = 30) usamap + coord_map("bonne", lat0 = 50) # World map, using geom_path instead of geom_polygon world <- map_data("world") worldmap <- ggplot(world, aes(x=long, y=lat, group=group)) + geom_path() + scale_y_continuous(breaks=(-2:2) * 30) + scale_x_continuous(breaks=(-4:4) * 45) # Orthographic projection with default orientation (looking down at North pole) worldmap + coord_map("ortho") # Looking up up at South Pole worldmap + coord_map("ortho", orientation=c(-90, 0, 0)) # Centered on New York (currently has issues with closing polygons) worldmap + coord_map("ortho", orientation=c(41, -74, 0)) }