crossing.psp {spatstat.geom}

Crossing Points of Two Line Segment Patterns

Description

Finds any crossing points between two line segment patterns.

Usage

  crossing.psp(A,B,fatal=TRUE,details=FALSE)

Arguments

A, B

Line segment patterns (objects of class "psp").

details

Logical value indicating whether to return additional information. See below.

fatal

Logical value indicating what to do if the windows of A and B do not overlap. See Details.

Details

This function finds any crossing points between the line segment patterns A and B.

A crossing point occurs whenever one of the line segments in A intersects one of the line segments in B, at a nonzero angle of intersection.

The result is a point pattern consisting of all the intersection points.

If details=TRUE, additional information is computed, specifying where each intersection point came from. The resulting point pattern has a data frame of marks, with columns named iA, jB, tA, tB. The marks iA and jB are the indices of the line segments in A and B, respectively, which produced each intersection point. The marks tA and tB are numbers between 0 and 1 specifying the position of the intersection point along the original segments.

If the windows Window(A) and Window(B) do not overlap, then an error will be reported if fatal=TRUE, while if fatal=FALSE an error will not occur and the result will be NULL.

Value

Point pattern (object of class "ppp").

Author(s)

Adrian Baddeley [e-mail] and Rolf Turner [e-mail]

See Also

selfcrossing.psp, psp.object, ppp.object.

Examples

  a <- psp(runif(10), runif(10), runif(10), runif(10), window=owin())
  b <- psp(runif(10), runif(10), runif(10), runif(10), window=owin())
  plot(a, col="green", main="crossing.psp")
  plot(b, add=TRUE, col="blue")
  P <- crossing.psp(a,b)
  plot(P, add=TRUE, col="red")
  as.data.frame(crossing.psp(a,b,details=TRUE))