spatstat (version 1.15-3)

quadrats: Divide Region into Quadrats

Description

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

Usage

quadrats(X, nx = 5, ny = nx, xbreaks = NULL, ybreaks = NULL)

Arguments

X

A window (object of class "owin") or anything that can be coerced to a window using as.owin, such as a point pattern.

nx,ny

Numbers of quadrats in the $x$ and $y$ directions. Incompatible with xbreaks and ybreaks.

xbreaks

Numeric vector giving the $x$ coordinates of the boundaries of the quadrats. Incompatible with nx.

ybreaks

Numeric vector giving the $y$ coordinates of the boundaries of the quadrats. Incompatible with ny.

Value

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

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 X$window.

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.

See Also

tess, quadratcount, quadrat.test, quadratresample

Examples

W <- square(10)
 Z <- quadrats(W, 4, 5)
 plot(Z)

 data(letterR)
 plot(quadrats(letterR, 5, 7))