Create a Tessellation

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

spatial, datagen
tess(..., xgrid = NULL, ygrid = NULL, tiles = NULL, image = NULL,
            window=NULL, keepempty=FALSE)
Cartesian coordinates of vertical and horizontal lines determining a grid of rectangles. Incompatible with other arguments.
List of tiles in the tessellation. A list, each of whose elements is a window (object of class "owin"). Incompatible with other arguments.
Pixel image which specifies the tessellation. Incompatible with other arguments.
Optional. The spatial region which is tessellated (i.e. the union of all the tiles). An object of class "owin".
Logical flag indicating whether empty tiles should be retained or deleted.

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: [object Object],[object Object],[object Object]

The optional argument window specifies the spatial region formed by the union of all the tiles. In other words it specifies the spatial region that is divided into tiles by the tessellation. If this argument is missing or NULL, it will be determined by computing the set union of all the tiles. This is a time-consuming computation. For efficiency it is advisable to specify the window. Note that the validity of the window will not be checked.

Empty tiles may occur, either because one of the entries in the list tiles is an empty window, or because one of the levels of the factor-valued pixel image image does not occur in the pixel data. When keepempty=TRUE, empty tiles are permitted. When keepempty=FALSE (the default), tiles are not allowed to be empty, and any empty tiles will be removed from the tessellation.

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

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


  • An object of class "tess" representing the tessellation.

See Also

plot.tess, [.tess, as.tess, tiles, intersect.tess, split.ppp, cut.ppp, by.ppp, quadrats, bdist.tiles, tile.areas.

  • tess
A <- tess(xgrid=0:4,ygrid=0:4)
  B <- A[c(1, 2, 5, 7, 9)]
  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)
Documentation reproduced from package spatstat, version 1.25-5, License: GPL (>= 2)

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