Convert Line Segment Pattern to Linear Network
Converts a line segment pattern to a linear network.
## S3 method for class 'psp' as.linnet(X, ..., eps, sparse=FALSE)
X |
Line segment pattern (object of class |
... |
Ignored. |
eps |
Optional. Distance threshold. If two segment endpoints
are closer than |
sparse |
Logical value indicating whether to use a sparse matrix
representation, as explained in |
This command converts any collection of line segments into a linear
network by guessing the connectivity of the network,
using the distance threshold eps.
If any segments in X cross over each other, they are first
cut into pieces using selfcut.psp.
Then any pair of segment endpoints lying closer than eps
units apart, is treated as a single vertex. The linear network
is then constructed using linnet.
It would be wise to check the result by plotting the degree of each vertex, as shown in the Examples.
If X has marks, then these are stored in
the resulting linear network Y <- as.linnet(X),
and can be extracted as marks(as.psp(Y)) or marks(Y$lines).
A linear network (object of class "linnet").
The result also has an attribute "camefrom" indicating
the provenance of each line in the resulting network.
For example camefrom[3]=2 means that the third line segment
in the result is a piece of the second segment of X.
Adrian Baddeley Adrian.Baddeley@curtin.edu.au, Rolf Turner r.turner@auckland.ac.nz and Ege Rubak rubak@math.aau.dk.
# make some data A <- psp(0.09, 0.55, 0.79, 0.80, window=owin()) B <- superimpose(A, as.psp(simplenet)) # convert to a linear network L <- as.linnet(B) # check validity L plot(L) text(vertices(L), labels=vertexdegree(L)) # show the pieces that came from original segment number 1 S <- as.psp(L) (camefrom <- attr(L, "camefrom")) parts <- which(camefrom == 1) plot(S[parts], add=TRUE, col="green", lwd=2)
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