# R igraph manual pages

Use this if you are using igraph from R

## Generate random graphs according to the random dot product graph model

### Description

In this model, each vertex is represented by a latent position vector. Probability of an edge between two vertices are given by the dot product of their latent position vectors.

### Usage

sample_dot_product(vecs, directed = FALSE)

dot_product(...)


### Arguments

 vecs A numeric matrix in which each latent position vector is a column. directed A logical scalar, TRUE if the generated graph should be directed. ... Passed to sample_dot_product.

### Details

The dot product of the latent position vectors should be in the [0,1] interval, otherwise a warning is given. For negative dot products, no edges are added; dot products that are larger than one always add an edge.

### Value

An igraph graph object which is the generated random dot product graph.

### Author(s)

Gabor Csardi csardi.gabor@gmail.com

### References

Christine Leigh Myers Nickel: Random dot product graphs, a model for social networks. Dissertation, Johns Hopkins University, Maryland, USA, 2006.

sample_dirichlet, sample_sphere_surface and sample_sphere_volume for sampling position vectors.

### Examples


## A randomly generated  graph
lpvs <- matrix(rnorm(200), 20, 10)
lpvs <- apply(lpvs, 2, function(x) { return (abs(x)/sqrt(sum(x^2))) })
g <- sample_dot_product(lpvs)
g

## Sample latent vectors from the surface of the unit sphere
lpvs2 <- sample_sphere_surface(dim=5, n=20)
g2 <- sample_dot_product(lpvs2)
g2


[Package igraph version 1.2.6 Index]