clusters {igraph} | R Documentation |

## Connected components of a graph

### Description

Calculate the maximal (weakly or strongly)
connected components of a graph

### Usage

is.connected(graph, mode=c("weak", "strong"))
clusters(graph, mode=c("weak", "strong"))
no.clusters(graph, mode=c("weak", "strong"))
cluster.distribution(graph, cumulative = FALSE, mul.size = FALSE, ...)

### Arguments

`graph` |
The graph to analyze. |

`mode` |
Character string, either “weak” or “strong”.
For directed graphs “weak” implies weakly, “strong”
strongly connected components to search. It is ignored for
undirected graphs. |

`cumulative` |
Logical, if TRUE the cumulative distirubution
(relative frequency) is calculated. |

`mul.size` |
Logical. If TRUE the relative frequencies will be
multiplied by the cluster sizes. |

`...` |
Additional attributes to pass to `cluster` , right
now only `mode` makes sense. |

### Details

`is.connected`

decides whether the graph is weakly or strongly
connected.

`clusters`

finds the maximal (weakly or strongly) connected
components of a graph.

`no.clusters`

does almost the same as `clusters`

but returns
only the number of clusters found instead of returning the actual
clusters.

`cluster.distribution`

creates a histogram for the maximal
connected component sizes.

Breadth-first search is conducted from each not-yet visited
vertex.

### Value

For `is.connected`

a logical constant.

For `clusters`

a named list with three components:

`membership` |
numeric vector giving the cluster id to which each
vertex belongs. |

`csize` |
numeric vector giving the sizes of the clusters. |

`no` |
numeric constant, the number of clusters. |

normal-bracket42bracket-normal

For `no.clusters`

an integer constant is returned.

For `cluster.distribution`

a numeric vector with the relative
frequencies. The length of the vector is the number of components.

### Author(s)

Gabor Csardi csardi@rmki.kfki.hu

### See Also

`subcomponent`

### Examples

g <- erdos.renyi.game(20, 1/20)
clusters(g)

[Package

*igraph* version 0.5.1

Index]