graph-motifs {igraph} R Documentation

## Graph motifs

### Description

Graph motifs are small subgraphs with a well-defined strucure. These functions search a graph for various motifs.

### Usage

```graph.motifs(graph, size = 3, cut.prob = rep(0, size))
graph.motifs.no(graph, size = 3, cut.prob = rep(0, size))
graph.motifs.est(graph, size = 3, cut.prob = rep(0, size), sample.size =
vcount(graph)/10, sample = NULL)
```

### Arguments

 `graph` Graph object, the input graph. `size` The size of the motif, currently 3 and 4 are supported only. `cut.prob` Numeric vector giving the probabilities that the search graph is cut at a certain level. Its length should be the same as the size of the motif (the `size` argument). By default no cuts are made. `sample.size` The number of vertices to use as a starting point for finding motifs. Only used if the `sample` argument is `NULL`. `sample` If not `NULL` then it specifies the vertices to use as a starting point for finding motifs.

### Details

`graph.motifs` searches a graph for motifs of a given size and returns a numeric vector containing the number of different motifs. The order of the motifs is defined by their isomorphism class, see `graph.isoclass`.

`graph.motifs.no` calculates the total number of motifs of a given size in graph.

`graph.motifs.est` estimates the total number of motifs of a given size in a graph based on a sample.

### Value

`graph.motifs` returns a numeric vector.
`graph.motifs.no` and `graph.motifs.est` return a numeric constant.

### Author(s)

Gabor Csardi csardi@rmki.kfki.hu

`graph.isoclass`
```g <- barabasi.game(100)