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Given a point pattern and a line segment pattern, this function finds the nearest line segment for each point.
nearestsegment(X, Y)Integer vector v (of length equal to the number of points in
X) identifying the nearest segment to each point.
If v[i] = j, then
Y[j] is the line segment lying closest to X[i].
A point pattern (object of class "ppp").
A line segment pattern (object of class "psp").
Adrian Baddeley Adrian.Baddeley@curtin.edu.au
and Rolf Turner rolfturner@posteo.net
The distance between a point x and a straight line segment y is
defined to be the shortest Euclidean distance between x and any
location on y. This algorithm first calculates the distance
from each point of X to
each segment of Y. Then it determines, for each point x in
X, which segment of Y is closest. The index of this
segment is returned.
project2segment to project each point of X to
a point lying on one of the line segments.
Use distmap.psp to
identify the nearest line segment for each pixel in a grid.
X <- runifrect(3)
Y <- as.psp(matrix(runif(20), 5, 4), window=owin())
v <- nearestsegment(X,Y)
plot(Y)
plot(X, add=TRUE)
plot(X[1], add=TRUE, col="red")
plot(Y[v[1]], add=TRUE, lwd=2, col="red")
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