# R igraph manual pages

Use this if you are using igraph from R

 sample_sphere_volume {igraph} R Documentation

## Sample vectors uniformly from the volume of a sphere

### Description

Sample finite-dimensional vectors to use as latent position vectors in random dot product graphs

### Usage

sample_sphere_volume(dim, n = 1, radius = 1, positive = TRUE)


### Arguments

 dim Integer scalar, the dimension of the random vectors. n Integer scalar, the sample size. radius Numeric scalar, the radius of the sphere to sample. positive Logical scalar, whether to sample from the positive orthant of the sphere.

### Details

sample_sphere_volume generates uniform samples from S^{dim-1} (the (dim-1)-sphere) i.e. the Euclidean norm of the samples is smaller or equal to radius.

### Value

A dim (length of the alpha vector for sample_dirichlet) times n matrix, whose columns are the sample vectors.

### See Also

Other latent position vector samplers: sample_dirichlet(), sample_sphere_surface()

### Examples

lpvs.sph.vol <- sample_sphere_volume(dim=10, n=20, radius=1)
RDP.graph.4  <- sample_dot_product(lpvs.sph.vol)
vec.norm     <- apply(lpvs.sph.vol, 2, function(x) { sum(x^2) })
vec.norm


[Package igraph version 1.3.5 Index]