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.
stratrand(window, nx, ny, k = 1)
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,
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
quadscheme) as well as in simulating
random point patterns.
- A list with two components
y, which are numeric vectors giving the coordinates of the random points.
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])