spatstat (version 1.63-0)

# nearest.raster.point: 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.

## 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.

## 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.

`owin.object`, `as.mask`

## Examples

```# NOT RUN {
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)
# }
```