spatstat.geom (version 3.7-0)

endpoints.psp: Endpoints of Line Segment Pattern

Description

Extracts the endpoints of each line segment in a line segment pattern.

Usage

endpoints.psp(x, which="both")

Value

Point pattern (object of class "ppp").

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.

See Also

psp.object, ppp.object, marks.psp, summary.psp, midpoints.psp, lengths_psp, angles.psp, extrapolate.psp.

Examples

  a <- psp(runif(10), runif(10), runif(10), runif(10), window=owin())
  plot(a)
  b <- endpoints.psp(a, "left")
  plot(b, add=TRUE)