# gridcentres

##### Rectangular grid of points

Generates a rectangular grid of points in a window

##### Usage

`gridcentres(window, nx, ny)`

##### Arguments

##### Details

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,
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`

) and for other miscellaneous
purposes.

##### Value

A list with two components `x`

and `y`

, which are numeric
vectors giving the coordinates of the points of the
rectangular grid.

##### See Also

##### Examples

```
# NOT RUN {
w <- unit.square()
xy <- gridcentres(w, 10,15)
# }
# NOT RUN {
plot(w)
points(xy)
# }
# NOT RUN {
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)
# }
# NOT RUN {
plot(w)
points(xy$x[ok], xy$y[ok])
# }
```

*Documentation reproduced from package spatstat, version 1.55-1, License: GPL (>= 2)*