Rectangular grid of points
Generates a rectangular grid of points in a window
gridcentres(window, nx, ny)
This function creates a rectangular grid of points in the window.
The bounding rectangle of the
window is divided into
a regular $nx \times ny$ grid of rectangular tiles.
The function returns the $x,y$ coordinates of the
centres of these tiles.
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) and for other miscellaneous
- A list with two components
y, which are numeric vectors giving the coordinates of the points of the rectangular grid.
library(spatstat) w <- unit.square() xy <- gridcentres(w, 10,15) plot(w) points(xy) 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 <- gridcentres(w, 30, 30) ok <- inside.owin(xy$x, xy$y, w) plot(w) points(xy$x[ok], xy$y[ok])