spatstat (version 1.64-1)

# connected.ppp: 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 ppp
connected(X, R, …)# S3 method for 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.

## Value

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

## 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.

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

## Examples

```# NOT RUN {
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="")
}
# }
```