R: Connected Components of a Point Pattern

connected.ppp {spatstat} | R Documentation

## Connected Components of a Point Pattern

### Description

Finds the topologically-connected components of a point pattern, when all pairs of points closer than a threshold distance are joined.

### Usage

    ## S3 method for class 'ppp'
    connected(X, R, ...)

    ## S3 method for class 'pp3'
    connected(X, R, ...)

### Arguments

`X` | A point pattern (object of class `"ppp"` or `"pp3"`).
`R` | Threshold distance. Pairs of points closer than `R` units apart will be joined together.
`...` | Other arguments, not recognised by these methods.

### Details

This function can be used to identify clumps of points in a point pattern.

The function `connected` is generic. This file documents the methods for point patterns in dimension two or three (objects of class `"ppp"` or `"pp3"`).

The point pattern `X` is first converted into an abstract graph by joining every pair of points that lie closer than `R` units apart. Then the connected components of this graph are identified.

Two points in `X` belong to the same connected component if they can be reached by a series of steps between points of `X`, each step being shorter than `R` units in length.

The result is a vector of labels for the points of `X` where all the points in a connected component have the same label.

### Value

A point pattern, equivalent to `X` except that the points have factor-valued marks, with levels corresponding to the connected components.

### 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

`connected.im`, `im.object`, `tess`

### Examples

       Y <- connected(redwoodfull, 0.1)
       if(interactive()) {
        plot(Y, cols=1:length(levels(marks(Y))),
             main="connected(redwoodfull, 0.1)")
       }
       X <- osteo$pts[[1]]
       Z <- connected(X, 32)
       if(interactive()) {
        plot(Z, col=marks(Z), main="")
       }

[Package spatstat version 1.63-3 Index]