R: Endpoints of Line Segment Pattern

endpoints.psp {spatstat.geom} | R Documentation

## Endpoints of Line Segment Pattern

### Description

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

### Usage

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

### Arguments

`x` | A line segment pattern (object of class `"psp"`).
`which` | String specifying which endpoint or endpoints should be returned. See Details.

### 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.

### 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

`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)

[Package spatstat.geom version 2.2-0 Index]