Generates a “systematic random” pattern of points in a window, consisting of a grid of equally-spaced points with a random common displacement.
rsyst(win=square(1), nx=NULL, ny=nx, …, dx=NULL, dy=dx,
nsim=1, drop=TRUE)Number of columns of grid points in the window.
Incompatible with dx.
Number of rows of grid points in the window.
Incompatible with dy.
Ignored.
Spacing of grid points in \(x\) direction.
Incompatible with nx.
Spacing of grid points in \(y\) direction.
Incompatible with ny.
Number of simulated realisations to be generated.
Logical. If nsim=1 and drop=TRUE (the default), the
result will be a point pattern, rather than a list
containing a point pattern.
A point pattern (an object of class "ppp")
if nsim=1, or a list of point patterns if nsim > 1.
This function generates a “systematic random” pattern
of points in the window win. The pattern consists of a
rectangular grid of points with a random common displacement.
The grid spacing in the \(x\) direction is determined
either by the number of columns nx or by the
horizontal spacing dx.
The grid spacing in the \(y\) direction is determined
either by the number of rows ny or by the
vertical spacing dy.
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.
# NOT RUN {
X <- rsyst(nx=10)
plot(X)
# polygonal boundary
data(letterR)
X <- rsyst(letterR, 5, 10)
plot(X)
# }
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