tess {spatstat}R Documentation

Create a Tessellation

Description

Creates an object of class "tess" representing a tessellation of a spatial region.

Usage

  tess(..., xgrid = NULL, ygrid = NULL, tiles = NULL, image = NULL)

Arguments

... Ignored.
xgrid,ygrid Cartesian coordinates of vertical and horizontal lines determining a grid of rectangles. Incompatible with other arguments.
tiles List of tiles in the tessellation. A list, each of whose elements is a window (object of class "owin"). Incompatible with other arguments.
image Pixel image which specifies the tessellation. Incompatible with other arguments.

Details

A tessellation is a collection of disjoint spatial regions (called tiles) that fit together to form a larger spatial region. This command creates an object of class "tess" that represents a tessellation.

Three types of tessellation are supported:

rectangular:
tiles are rectangles, with sides parallel to the x and y axes. They may or may not have equal size and shape. The arguments xgrid and ygrid determine the positions of the vertical and horizontal grid lines, respectively.
tile list:
tiles are arbitrary spatial regions. The argument tiles is a list of these tiles, which are objects of class "owin".
pixel image:
Tiles are subsets of a fine grid of pixels. The argument image is a pixel image (object of class "im") with factor values. Each level of the factor represents a different tile of the tessellation. The pixels that have a particular value of the factor constitute a tile.

There are methods for print, plot, [ and [<- for tessellations. Use tiles to extract the list of tiles in a tessellation.

Tessellations can be used to classify the points of a point pattern, in split.ppp, cut.ppp and by.ppp.

Value

An object of class "tess" representing the tessellation.

Author(s)

Adrian Baddeley adrian@maths.uwa.edu.au http://www.maths.uwa.edu.au/~adrian/ and Rolf Turner r.turner@auckland.ac.nz

See Also

plot.tess, [.tess, tiles, split.ppp, cut.ppp, by.ppp.

Examples

  A <- tess(xgrid=0:4,ygrid=0:4)
  A
  B <- A[c(1, 2, 5, 7, 9)]
  B
  v <- as.im(function(x,y){factor(round(5 * (x^2 + y^2)))}, W=owin())
  levels(v) <- letters[seq(length(levels(v)))]
  E <- tess(image=v)
  E

[Package spatstat version 1.14-0 Index]