rsyst
Simulate systematic random point pattern
Generates a ``systematic random'' pattern of points in a window, consisting of a grid of equally-spaced points with a random common displacement.
Usage
rsyst(win=square(1), nx, ny=nx, dx=NULL, dy=NULL)Arguments
- win
- A window.
An object of class
owin, or data in any format acceptable toas.owin(). - dx
- Spacing of grid points in $x$ direction.
Incompatible with
nx. - dy
- Spacing of grid points in $y$ direction.
Incompatible with
ny. - nx
- Number of columns of grid points in the window.
Incompatible with
dx. - ny
- Number of rows of grid points in the window.
Incompatible with
dy.
Details
This function generates a win. The pattern consists of a rectangular grid
of points with a random common displacement.
The grid spacing is determined by the distances dx, dy
if they are present. If they are absent, then the grid spacing is
determined so that there will be nx columns and ny rows
of grid points in the bounding rectangle of win.
The grid is then given a random displacement (the common displacement
of the grid points is a uniformly distributed random vector in the
tile of dimensions dx, dy).
Some of the resulting grid points may lie outside the window win:
if they do, they are deleted.
The result is a point pattern inside the window win.
This function is useful in creating dummy points for quadrature
schemes (see quadscheme) as well as in simulating
random point patterns.
Value
- A point pattern (object of class
"ppp").
See Also
Examples
X <- rsyst(nx=10)
plot(X)
# polygonal boundary
data(letterR)
X <- rsyst(letterR, 5, 10)
plot(X)