# gridcentres

From spatstat v1.1-3
by Adrian Baddeley

##### Rectangular grid of points

Generates a rectangular grid of points in a window

- Keywords
- spatial

##### 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

```
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])
```

*Documentation reproduced from package spatstat, version 1.1-3, License: GPL version 2 or newer*

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