| mapasp {sp} | R Documentation |
Calculate aspect ratio for plotting geographic maps
mapasp(data, xlim, ylim)
data |
object of class or extending Spatial |
xlim |
the xlim argument passed (or derived from bounding box) |
ylim |
the ylim argument passed (or derived from bounding box) |
mapasp is used for the aspect argument in lattice plots and spplot;
let x = dy/dx, with dy and dx the y- and x-size of the map.
let s = 1/cos(My * pi)/180) with My the y coordinate of the middle of the map
(the mean of ylim)
for latlong (longlat) data, mapasp returns s * x.
for other data, mapasp returns "iso".
levelplot in package lattice