rthin
Random Thinning
Applies independent random thinning to a point pattern.
Usage
rthin(X, P, ...)Arguments
- X
- A point pattern (object of class
"ppp") that will be thinned. - P
- Data giving the retention probabilities, i.e. the probability
that each point in
Xwill be retained. Either a single number, or a vector of numbers, or afunction(x,y), or a pixel image (object of class"im" - ...
- Additional arguments passed to
P, if it is a function.
Details
In a random thinning operation, each point of the pattern X
is randomly either deleted or retained (i.e. not deleted).
The result is a point pattern,
consisting of those points of X that were retained.
Independent random thinning means that the retention/deletion of each point is independent of other points.
The argument P determines the probability of retaining
each point. It may be
[object Object],[object Object],[object Object],[object Object]
If P is a function, it should be x,y and should yield a
numeric vector of the same length. The function may have extra
arguments which are passed through the ... argument.
Value
- A point pattern (object of class
"ppp").
Examples
data(redwood)
plot(redwood, main="thinning")
# delete 20\% of points
Y <- rthin(redwood, 0.8)
points(Y, col="green", cex=1.4)
# function
f <- function(x,y) { ifelse(x < 0.4, 1, 0.5) }
Y <- rthin(redwood, f)
# pixel image
Z <- as.im(f, redwood$window)
Y <- rthin(redwood, Z)