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 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.
For calculations using quadrats, see
quadratcount,
quadrat.test,
quadratresample
For other kinds of tessellations, see
tess,
hextess,
venn.tess,
polartess,
dirichlet, delaunay,
quantess, bufftess
and
rpoislinetess.
W <- square(10)
Z <- quadrats(W, 4, 5)
plot(Z)
plot(quadrats(letterR, 5, 7))
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