Simulate Simple Sequential Inhibition
Generate a random point pattern, a realisation of the Simple Sequential Inhibition (SSI) process.
rSSI(r, n=Inf, win = square(1), giveup = 1000, x.init=NULL)
- Inhibition distance.
- Maximum number of points allowed.
nis finite, stop when the total number of points in the point pattern reaches
nis infinite (the default), stop only when it is apparently impossi
- Window in which to simulate the pattern.
An object of class
"owin"or something acceptable to
as.owin. The default window is the unit square, unless
- Number of rejected proposals after which the algorithm should terminate.
- Optional. Initial configuration of points. A point pattern
(object of class
"ppp"). The pattern returned by
rSSIconsists of this pattern together with the points added via simple sequential inhibition. See Detai
This algorithm generates a realisation of the Simple Sequential
Inhibition point process inside the window
Starting with an empty window (or with the point pattern
x.init if specified), the algorithm adds points
one-by-one. Each new point is generated uniformly in the window
and independently of preceding points. If the new point lies
r units from an existing point, then it is
rejected and another random point is generated.
The algorithm terminates when either
[object Object],[object Object]
n is infinite (the default) then the algorithm terminates
only when (b) occurs. The result is sometimes called a
Random Sequential Packing.
Note that argument
n specifies the maximum permitted
total number of points in the pattern returned by
x.init is not
the number of points that are added
is at most
n - npoints(x.init) if
n is finite.
x.init is not
NULL then argument
must be at least as large as
an error is given. If
n==npoints(x.init) then a warning
is given and the call to
rSSI() has no real effect;
x.init is returned.
There is no requirement that the points of
x.init be at
a distance at least
r from each other. All of the added
points will be at a distance at least
r from each other
and from any point of
The points will be generated inside the window
and the result will be a point pattern in the same window.
The default window is the unit square,
win = square(1),
x.init is specified, when the default
win=as.owin(x.init), the window of
x.init are specified, and if the
two windows are different, then a warning will be issued.
Any points of
x.init lying outside
win will be removed,
with a warning.
- The simulated point pattern (an object of class
Vinf <- rSSI(0.05) V100 <- rSSI(0.05, 100) X <- runifpoint(100) Y <- rSSI(0.03,142,x.init=X) # Y consists of X together with # 42 added points. plot(Y) plot(X,add=TRUE,chars=20,cols="red")