quadrats
Divide Region into Quadrats
Divides window into rectangular quadrats and returns the quadrats as a tessellation.
Usage
quadrats(X, nx = 5, ny = nx, xbreaks = NULL, ybreaks = NULL, keepempty=FALSE)
Arguments
 X

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

Numbers of quadrats in the $x$ and $y$ directions.
Incompatible with
xbreaks
andybreaks
.  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
.  keepempty
 Logical value indicating whether to delete or retain empty quadrats. See Details.
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 nonempty 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
.
See Also
Examples
W < square(10)
Z < quadrats(W, 4, 5)
plot(Z)
data(letterR)
plot(quadrats(letterR, 5, 7))