area.owin {spatstat.geom}

Area of a Window

Description

Computes the area of a window

Usage

 area(w)

 ## S3 method for class 'owin'
area(w)

 ## Default S3 method:
area(w)

 ## S3 method for class 'owin'
volume(x)

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().

x

Object of class 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.

The function volume.owin is identical to area.owin except for the argument name. It is a method for the generic function volume.

Value

A numerical value giving the area of the window.

Author(s)

Adrian Baddeley [e-mail]

and Rolf Turner [e-mail]

See Also

perimeter, diameter.owin, owin.object, as.owin

Examples

  w <- unit.square()
  area(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(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(mas)
       # returns 3.14 approx