R: Connected Components of a Point Pattern on a Linear Network

connected.lpp {spatstat.linnet} | R Documentation

## Connected Components of a Point Pattern on a Linear Network

### Description

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

### Usage

    ## S3 method for class 'lpp'
    connected(X, R=Inf, ..., dismantle=TRUE)

### Arguments

`X` | A linear network (object of class `"lpp"`).
`R` | Threshold distance. Pairs of points will be joined together if they are closer than `R` units apart, measured by the shortest path in the network. The default `R=Inf` implies that points will be joined together if they are mutually connected by any path in the network.
`dismantle` | Logical. If `TRUE` (the default), the network itself will be divided into its path-connected components using `connected.linnet`.
`...` | Ignored.

### Details

The function `connected` is generic. This is the method for point patterns on a linear network (objects of class `"lpp"`). It divides the point pattern `X` into one or more groups of points.

If `R=Inf` (the default), then `X` is divided into groups such that any pair of points in the same group can be joined by a path in the network.

If `R` is a finite number, then two points of `X` are declared to be R-close if they lie closer than `R` units apart, measured by the length of the shortest path in the network. Two points are R-connected if they can be reached by a series of steps between R-close pairs of points of `X`. Then `X` is divided into groups such that any pair of points in the same group is R-connected.

If `dismantle=TRUE` (the default) the algorithm first checks whether the network is connected (i.e. whether any pair of vertices can be joined by a path in the network), and if not, the network is decomposed into its connected components.

### Value

A point pattern (of class `"lpp"`) with marks indicating the grouping, or a list of such point patterns.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au.

### See Also

`thinNetwork`

### Examples

       ## behaviour like connected.ppp
       U <- runiflpp(20, simplenet)
       plot(connected(U, 0.15, dismantle=FALSE))

       ## behaviour like connected.owin
       ## remove some edges from a network to make it disconnected
       plot(simplenet, col="grey", main="", lty=2)
       A <- thinNetwork(simplenet, retainedges=-c(3,5))
       plot(A, add=TRUE, lwd=2)
       X <- runiflpp(10, A)
       ## find the connected components
       cX <- connected(X)
       plot(cX[[1]], add=TRUE, col="blue", lwd=2)

[Package spatstat.linnet version 2.3-1 Index]