mapasp function

Calculate aspect ratio for plotting geographic maps; create nice degree axis labels

mapasp(data, xlim, ylim)
degreeLabelsEW(x)
degreeLabelsNS(x)

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)
• x: numeric; values at which tics and marks will be generated

Returns

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".

Note

the values for x are typically obtained from axTicks

See Also

levelplot in package lattice