# sample_dot_product

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

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.

- Keywords
- graphs

##### Usage

`sample_dot_product(vecs, directed = FALSE)`

##### 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.

##### References

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

##### See Also

`sample_dirichlet`

, `sample_sphere_surface`

and `sample_sphere_volume`

for sampling position vectors.

##### Examples

```
# NOT RUN {
## 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
# }
```

*Documentation reproduced from package igraph, version 1.2.3, License: GPL (>= 2)*