Description

Divides window into rectangular quadrats and returns the quadrats as a tessellation.

Usage

Arguments

Details

If the window X is a rectangle, it is divided into an nx * ny grid of rectangular tiles or ‘quadrats’.

If X is not a rectangle, then the bounding rectangle of X is first divided into an nx * ny grid of rectangular tiles, and these tiles are then intersected with the window X.

The resulting tiles are returned as a tessellation (object of class "tess") which can be plotted and used in other analyses.

If xbreaks is given, it should be a numeric vector giving the x coordinates of the quadrat boundaries. If it is not given, it defaults to a sequence of nx+1 values equally spaced over the range of x coordinates in the window Window(X).

Similarly if ybreaks is given, it should be a numeric vector giving the y coordinates of the quadrat boundaries. It defaults to a vector of ny+1 values equally spaced over the range of y coordinates in the window. The lengths of xbreaks and ybreaks may be different.

By default (if keepempty=FALSE), any rectangular tile which does not intersect the window X is ignored, and only the non-empty intersections are treated as quadrats, so the tessellation may consist of fewer than nx * ny tiles. If keepempty=TRUE, empty intersections are retained, and the tessellation always contains exactly nx * ny tiles, some of which may be empty.

Value

A tessellation (object of class "tess") as described under tess.

Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

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

See Also

For calculations using quadrats, see quadratcount, quadrat.test, quadratresample

For other kinds of tessellations, see tess, hextess, venn.tess, polartess, dirichlet, delaunay, rpoislinetess and quantess.

Examples