Endpoints of Line Segment Pattern
Extracts the endpoints of each line segment in a line segment pattern.
endpoints.psp(x, which="both")
x |
A line segment pattern (object of class |
which |
String specifying which endpoint or endpoints should be returned. See Details. |
This function extracts one endpoint, or both endpoints,
from each of the line segments in x,
and returns these points as a point pattern object.
The argument which determines which endpoint or endpoints
of each line segment should be returned:
which="both"(the default): both endpoints
of each line segment are returned. The result is a point pattern
with twice as many points as there are line segments in x.
which="first"select the first endpoint
of each line segment (returns the points with coordinates
x$ends$x0, x$ends$y0).
which="second"select the second endpoint
of each line segment (returns the points with coordinates
x$ends$x1, x$ends$y1).
which="left"select the left-most endpoint (the endpoint with the smaller x coordinate) of each line segment.
which="right"select the right-most endpoint (the endpoint with the greater x coordinate) of each line segment.
which="lower"select the lower endpoint (the endpoint with the smaller y coordinate) of each line segment.
which="upper"select the upper endpoint (the endpoint with the greater y coordinate) of each line segment.
The result is a point pattern. It also has an attribute
"id" which is an integer vector identifying
the segment which contributed each point.
Point pattern (object of class "ppp").
Adrian Baddeley Adrian.Baddeley@curtin.edu.au
and Rolf Turner r.turner@auckland.ac.nz
a <- psp(runif(10), runif(10), runif(10), runif(10), window=owin()) plot(a) b <- endpoints.psp(a, "left") plot(b, add=TRUE)
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