R: Find Pixel Nearest to a Given Point

nearest.raster.point {spatstat} | R Documentation

## Find Pixel Nearest to a Given Point

### Description

Given cartesian coordinates, find the nearest pixel.

### Usage

     nearest.raster.point(x,y,w, indices=TRUE)

### Arguments

`x` | Numeric vector of x coordinates of any points
`y` | Numeric vector of y coordinates of any points
`w` | An image (object of class `"im"`) or a binary mask window (an object of class `"owin"` of type `"mask"`).
`indices` | Logical flag indicating whether to return the row and column indices, or the actual x,y coordinates.

### Details

The argument `w` should be either a pixel image (object of class `"im"`) or a window (an object of class `"owin"`, see `owin.object` for details) of type `"mask"`.

The arguments `x` and `y` should be numeric vectors of equal length. They are interpreted as the coordinates of points in space. For each point `(x[i], y[i])`, the function finds the nearest pixel in the grid of pixels for `w`.

If `indices=TRUE`, this function returns a list containing two vectors `rr` and `cc` giving row and column positions (in the image matrix). For the location `(x[i],y[i])` the nearest pixel is at row `rr[i]` and column `cc[i]` of the image.

If `indices=FALSE`, the function returns a list containing two vectors `x` and `y` giving the actual coordinates of the pixels.

### Value

If `indices=TRUE`, a list containing two vectors `rr` and `cc` giving row and column positions (in the image matrix). If `indices=FALSE`, a list containing vectors `x` and `y` giving actual coordinates of the pixels.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

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

### See Also

`owin.object`, `as.mask`

### Examples

      w <- owin(c(0,1), c(0,1), mask=matrix(TRUE, 100,100))  # 100 x 100 grid
      nearest.raster.point(0.5, 0.3, w)
      nearest.raster.point(0.5, 0.3, w, indices=FALSE)

[Package spatstat version 1.63-3 Index]