area.owin {spatstat} | R Documentation |
Computes the area of a window
area.owin(w)
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() .
|
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.
A numerical value giving the area of the window.
Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/ and Rolf Turner r.turner@auckland.ac.nz
perimeter
,
diameter
,
owin.object
,
as.owin
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