R: Compute Minimum or Maximum Nearest-Neighbour Distance

maxnndist {spatstat.geom} | R Documentation

## Compute Minimum or Maximum Nearest-Neighbour Distance

### Description

A faster way to compute the minimum or maximum nearest-neighbour distance in a point pattern.

### Usage

    minnndist(X, positive=FALSE, by=NULL)
    maxnndist(X, positive=FALSE, by=NULL)

### Arguments

`X` | A point pattern (object of class `"ppp"`).
`positive` | Logical. If `FALSE` (the default), compute the usual nearest-neighbour distance. If `TRUE`, ignore coincident points, so that the nearest neighbour distance for each point is greater than zero.
`by` | Optional. A factor, which separates `X` into groups. The algorithm will compute the distance to the nearest point in each group.

### Details

These functions find the minimum and maximum values of nearest-neighbour distances in the point pattern `X`. `minnndist(X)` and `maxnndist(X)` are equivalent to, but faster than, `min(nndist(X))` and `max(nndist(X))` respectively.

The value is `NA` if `npoints(X) < 2`.

### Value

A single numeric value (possibly `NA`).

If `by` is given, the result is a numeric matrix giving the minimum or maximum nearest neighbour distance between each subset of `X`.

### 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

`nndist`

### Examples

      min(nndist(swedishpines))
      minnndist(swedishpines)

      max(nndist(swedishpines))
      maxnndist(swedishpines)

      minnndist(lansing, positive=TRUE)

      if(interactive()) {
         X <- runifrect(1e6)
         system.time(min(nndist(X)))
         system.time(minnndist(X))
      }

      minnndist(amacrine, by=marks(amacrine))
      maxnndist(amacrine, by=marks(amacrine))

[Package spatstat.geom version 2.3-2 Index]