Connected Components of a Point Pattern
Finds the topologically-connected components of a point pattern, when all pairs of points closer than a threshold distance are joined.
## S3 method for class 'ppp' connected(X, R, ...) ## S3 method for class 'pp3' connected(X, R, ...)
X |
A point pattern (object of class |
R |
Threshold distance. Pairs of points closer than |
... |
Other arguments, not recognised by these methods. |
This function can be used to identify clumps of points in a point pattern.
The function connected is generic. This file documents the methods for
point patterns in dimension two or three (objects of class "ppp" or
"pp3").
The point pattern X is first converted into an abstract graph
by joining every pair of points that lie closer than R units
apart. Then the connected components of this graph are identified.
Two points in X belong to the same connected component if they
can be reached by a series of steps between points of X,
each step being shorter than R units in length.
The result is a vector of labels for the points of X
where all the points in a connected component have the same label.
A point pattern, equivalent to X except that the points
have factor-valued marks, with levels corresponding to the
connected components.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au, Rolf Turner r.turner@auckland.ac.nz and Ege Rubak rubak@math.aau.dk.
Y <- connected(redwoodfull, 0.1)
if(interactive()) {
plot(Y, cols=1:length(levels(marks(Y))),
main="connected(redwoodfull, 0.1)")
}
X <- osteo$pts[[1]]
Z <- connected(X, 32)
if(interactive()) {
plot(Z, col=marks(Z), main="")
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