sp (version 0.9-78)

mapasp: Calculate aspect ratio for plotting geographic maps

Description

Calculate aspect ratio for plotting geographic maps

Usage

mapasp(data, xlim, ylim)

Arguments

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)

Value

• 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".

See Also

levelplot in package lattice