R: Class of Line Segment Patterns

psp.object {spatstat} | R Documentation

## Class of Line Segment Patterns

### Description

A class `"psp"` to represent a spatial pattern of line segments in the plane. Includes information about the window in which the pattern was observed. Optionally includes marks.

### Details

An object of this class represents a two-dimensional pattern of line segments. It specifies

- the locations of the line segments (both endpoints)

- the window in which the pattern was observed

- optionally, a “mark” attached to each line segment (extra information such as a type label).

If `X` is an object of type `psp`, it contains the following elements:

`ends` | data frame with entries `x0, y0, x1, y1`
| giving coordinates of segment endpoints
`window` | window of observation
| (an object of class `owin`)
`n` | number of line segments
`marks` | optional vector or data frame of marks
`markformat` | character string specifying the format of the
| marks; “none”, “vector”, or “dataframe”

Users are strongly advised not to manipulate these entries directly.

Objects of class `"psp"` may be created by the function `psp` and converted from other types of data by the function `as.psp`. Note that you must always specify the window of observation; there is intentionally no default action of “guessing” the window dimensions from the line segments alone.

Subsets of a line segment pattern may be obtained by the functions `[.psp` and `clip.psp`.

Line segment pattern objects can be plotted just by typing `plot(X)` which invokes the `plot` method for line segment pattern objects, `plot.psp`. See `plot.psp` for further information.

There are also methods for `summary` and `print` for line segment patterns. Use `summary(X)` to see a useful description of the data.

Utilities for line segment patterns include `midpoints.psp` (to compute the midpoints of each segment), `lengths.psp`, (to compute the length of each segment), `angles.psp`, (to compute the angle of orientation of each segment), and `distmap.psp` to compute the distance map of a line segment pattern.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

and Rolf Turner r.turner@auckland.ac.nz

### See Also

`psp`, `as.psp`, `[.psp`

### Examples

    # creating
        a <- psp(runif(20),runif(20),runif(20),runif(20), window=owin())
    # converting from other formats
        a <- as.psp(matrix(runif(80), ncol=4), window=owin())
        a <- as.psp(data.frame(x0=runif(20), y0=runif(20),
                                x1=runif(20), y1=runif(20)), window=owin())
    # clipping
        w <- owin(c(0.1,0.7), c(0.2, 0.8))
        b <- clip.psp(a, w)
        b <- a[w]
    # the last two lines are equivalent.

[Package spatstat version 1.54-0 Index]