R: Tessellation Using Polar Coordinates

polartess {spatstat} | R Documentation

## Tessellation Using Polar Coordinates

### Description

Create a tessellation with tiles defined by polar coordinates (radius and angle).

### Usage

    polartess(W, ..., nradial = NULL, nangular = NULL,
              radii = NULL, angles = NULL,
              origin = NULL, sep = "x")

### Arguments

`W` | A window (object of class `"owin"`) or anything that can be coerced to a window using `as.owin`, such as a point pattern.
`...` | Ignored.
`nradial` | Number of tiles in the radial direction. A single integer. Ignored if `radii` is given.
`nangular` | Number of tiles in the angular coordinate. A single integer. Ignored if `angles` is given.
`radii` | The numeric values of the radii, defining the tiles in the radial direction. A numeric vector, of length at least 2, containing nonnegative numbers in increasing order. The value `Inf` is permitted.
`angles` | The numeric values of the angles defining the tiles in the angular coordinate. A numeric vector, of length at least 2, in increasing order, containing angles in radians.
`origin` | Location to be used as the origin of the polar coordinates. Either a numeric vector of length 2 giving the spatial location of the origin, or one of the strings `"centroid"`, `"midpoint"`, `"left"`, `"right"`, `"top"`, `"bottom"`, `"topleft"`, `"bottomleft"`, `"topright"` or `"bottomright"` indicating the location in the window.
`sep` | Argument passed to `intersect.tess` specifying the character string to be used as a separator when forming the names of the tiles.

### Details

A tessellation will be formed from tiles defined by intervals in the polar coordinates r (radial distance from the origin) or θ (angle from the horizontal axis) or both. These tiles look like the cells on a dartboard.

If the argument `radii` is given, tiles will be demarcated by circles centred at the origin, with the specified radii. If `radii` is absent but `nradial` is given, then `radii` will default to a sequence of `nradial+1` radii equally spaced from zero to the maximum possible radius. If neither `radii` nor `nradial` are given, the tessellation will not include circular arc boundaries.

If the argument `angles` is given, tiles will be demarcated by lines emanating from the origin at the specified angles. The angular values can be any real numbers; they will be interpreted as angles in radians modulo `2*pi`, but they must be an increasing sequence of numbers. If `angles` is absent but `nangular` is given, then `angles` will default to a sequence of `nangular+1` angles equally spaced from 0 to `2*pi`. If neither `angles` nor `nangular` are given, the tessellation will not include linear boundaries.

### Value

A tessellation (object of class `"tess"`).

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au.

### See Also

`intersect.tess`

To construct other kinds of tessellations, see `tess`, `quadrats`, `hextess`, `venn.tess`, `dirichlet`, `delaunay`, `quantess` and `rpoislinetess`.

### Examples

      Y <- c(2.8, 1.5)
      plot(polartess(letterR, nangular=6, radii=(0:4)/2, origin=Y),
           do.col=TRUE)

[Package spatstat version 1.63-3 Index]