R: Find Nearest Point in a Region

project2set {spatstat.geom} | R Documentation

## Find Nearest Point in a Region

### Description

For each data point in a point pattern `X`, find the nearest location in a given spatial region `W`.

### Usage

      project2set(X, W, ...)

### Arguments

`X` | Point pattern (object of class `"ppp"`).
`W` | Window (object of class `"owin"`) or something acceptable to `as.owin`.
`...` | Arguments passed to `as.mask` controlling the pixel resolution.

### Details

The window `W` is first discretised as a binary mask using `as.mask`.

For each data point `X[i]` in the point pattern `X`, the algorithm finds the nearest pixel in `W`.

The result is a point pattern `Y` containing these nearest points, that is, `Y[i]` is the nearest point in `W` to the point `X[i]`.

### Value

A point pattern (object of class `"ppp"`) with the same number of points as `X` in the window `W`.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au

Rolf Turner r.turner@auckland.ac.nz

and Ege Rubak rubak@math.aau.dk

### See Also

`project2segment`, `nncross`

### Examples

      He <- heather$fine[owin(c(2.8, 7.4), c(4.0, 7.8))]
      plot(He, main="project2set")
      W <- erosion(complement.owin(He), 0.2)
    if(require(spatstat.core)) {
      X <- runifpoint(4, W)
    } else {
      X <- ppp(c(6.1, 4.3, 5.7, 4.7), c(5.0, 6.6, 7.5, 4.9), window=W)
    }
      points(X, col="red")
      Y <- project2set(X, He)
      points(Y, col="green")
      arrows(X$x, X$y, Y$x, Y$y, angle=15, length=0.2)

[Package spatstat.geom version 2.2-0 Index]