Software and Programmer Efficiency Research Group

The coordinate system of a plot, together with the x and y position scale, determines the location of geoms.

• coord_cartesian - (default) cartesian coordinate system (x horizontal from left to right, y vertical from bottom to top)
• coord_flip - flipped cartesian coordinate system (x vertical from bottom to top, y horizontal from left to right)
• coord_trans
• coord_equal
• coord_polar - polar coordinate system; the x (or y) scale is mapped to the angle (theta)
• coord_map - various map projections

Example

Assume the following data frame:

d=data.frame(height=c(1,2,2,3,4), weight=c(1,3,4,4,2))

And assume the following plot:

p = ggplot() +
geom_line(data=d, mapping=aes(x=height, y=weight)) +
geom_point(data=d, mapping=aes(x=height, y=weight), size=8, fill="white", shape=21) +
geom_text(data=d,mapping=aes(x=height, y=weight, label=seq(1,nrow(d))))

coord_cartesian

p + coord_cartesian()

coord_flip

p + coord_flip()

coord_trans

p + coord_trans(xtrans="log10", ytrans="log10")

coord_equal

p + coord_equal()

coord_polar

p + coord_polar(theta="x")

p + coord_polar(theta="y")

Example with coord_map

Load the "maps" package and create a data frame containing the latitudes and longitudes of the map of Italy.

require(maps)
d = data.frame(map(database="italy", plot=F)[c("x", "y")])

Create a plot using coord_map with its default (mercator) projection:

ggplot() +
coord_map() +
geom_polygon(data=d, mapping=aes(x=x, y=y), fill=hsv(0, 1, 0.7), color=hsv(0, 1, 0.5), size=0.2)