R: Rectangular grid of points

gridcentres {spatstat.geom} | R Documentation

## Rectangular grid of points

### Description

Generates a rectangular grid of points in a window

### Usage

     gridcentres(window, nx, ny)

### Arguments

`window` | A window. An object of class `owin`, or data in any format acceptable to `as.owin()`.
`nx` | Number of points in each row of the rectangular grid.
`ny` | Number of points in each column of the rectangular grid.

### Details

This function creates a rectangular grid of points in the window.

The bounding rectangle of the `window` is divided into a regular nx * 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.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

and Rolf Turner r.turner@auckland.ac.nz

### See Also

`quad.object`, `quadscheme`, `inside.owin`, `stratrand`

### Examples

      w <- unit.square()
      xy <- gridcentres(w, 10,15)
      if(human <- interactive()) {
      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)
      if(human) {
      plot(w)
      points(xy$x[ok], xy$y[ok])
      }

[Package spatstat.geom version 2.2-0 Index]