area.owin {spatstat}R Documentation

Area of a Window

Description

Computes the area of a window

Usage

 area.owin(w)

Arguments

w A window, whose area will be computed. This should be an object of class owin, or can be given in any format acceptable to as.owin().

Details

If the window W is of type "rectangle" or "polygonal", the area of this rectangular window is computed by analytic geometry. If W is of type "mask" the area of the discrete raster approximation of the window is computed by summing the binary image values and adjusting for pixel size.

Value

A numerical value giving the area of the window.

Author(s)

Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/ and Rolf Turner r.turner@auckland.ac.nz

See Also

perimeter, diameter, owin.object, as.owin

Examples

  w <- unit.square()
  area.owin(w)
       # returns 1.00000

  k <- 6
  theta <- 2 * pi * (0:(k-1))/k
  co <- cos(theta)
  si <- sin(theta)
  mas <- owin(c(-1,1), c(-1,1), poly=list(x=co, y=si))
  area.owin(mas)
      # returns approx area of k-gon
  
  mas <- as.mask(square(2), eps=0.01)
  X <- raster.x(mas)
  Y <- raster.y(mas)
  mas$m <- ((X - 1)^2 + (Y - 1)^2 <= 1)
  area.owin(mas)
       # returns 3.14 approx     


[Package spatstat version 1.17-0 Index]