Divides window into rectangular quadrats and returns the quadrats as a tessellation.
quadrats(X, nx = 5, ny = nx, xbreaks = NULL, ybreaks = NULL, keepempty=FALSE)A window (object of class "owin")
or anything that can be coerced to a window using
as.owin, such as a point pattern.
Numbers of quadrats in the \(x\) and \(y\) directions.
Incompatible with xbreaks and ybreaks.
Numeric vector giving the \(x\) coordinates of the
boundaries of the quadrats. Incompatible with nx.
Numeric vector giving the \(y\) coordinates of the
boundaries of the quadrats. Incompatible with ny.
Logical value indicating whether to delete or retain empty quadrats. See Details.
A tessellation (object of class "tess") as described under
tess.
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.
# NOT RUN {
W <- square(10)
Z <- quadrats(W, 4, 5)
plot(Z)
data(letterR)
plot(quadrats(letterR, 5, 7))
# }
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