R: Crossing Points of Two Line Segment Patterns

crossing.psp {spatstat.geom} | R Documentation

## 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 Adrian.Baddeley@curtin.edu.au and Rolf Turner r.turner@auckland.ac.nz

### 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))

[Package spatstat.geom version 2.2-0 Index]