stratrand
From spatstat v1.3-4
by Adrian Baddeley
Stratified random point pattern
Generates a ``stratified random'' pattern of points in a window,
by dividing the window into rectangular tiles and placing
k
random points in each tile.
- Keywords
- spatial
Usage
stratrand(window, nx, ny, k = 1)
Arguments
Details
The bounding rectangle of window
is divided into
a regular $nx \times ny$ grid of rectangular tiles.
In each tile, k
random points are generated independently
with a uniform distribution in that tile.
Note that some of these grid points may lie outside the window,
if window
is not of type "rectangle"
. The function
inside.owin
can be used to select those grid points
which do lie inside the window. See the examples.
This function is useful in creating dummy points for quadrature
schemes (see quadscheme
) as well as in simulating
random point patterns.
Value
- A list with two components
x
andy
, which are numeric vectors giving the coordinates of the random points.
See Also
Examples
library(spatstat)
w <- unit.square()
xy <- stratrand(w, 10, 10)
plot(w)
points(xy)
# polygonal boundary
bdry <- list(x=c(0.1,0.3,0.7,0.4,0.2),
y=c(0.1,0.1,0.5,0.7,0.3))
w <- owin(c(0,1), c(0,1), poly=bdry)
xy <- stratrand(w, 10, 10, 3)
plot(w)
points(xy)
# determine which grid points are inside polygon
ok <- inside.owin(xy$x, xy$y, w)
plot(w)
points(xy$x[ok], xy$y[ok])
Community examples
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