R: Examples for 'igraph::spectrum'

### ** Examples


## Small example graph, leading eigenvector by default
kite <- make_graph("Krackhardt_kite")
spectrum(kite)[c("values", "vectors")]

$values
[1] 4.306404

$vectors
            [,1]
 [1,] 0.35220940
 [2,] 0.35220940
 [3,] 0.28583499
 [4,] 0.48102086
 [5,] 0.28583499
 [6,] 0.39769064
 [7,] 0.39769064
 [8,] 0.19586058
 [9,] 0.04807349
[10,] 0.01116326

## Double check
eigen(as_adj(kite, sparse=FALSE))$vectors[,1]

 [1] -0.35220940 -0.35220940 -0.28583499 -0.48102086 -0.28583499 -0.39769064
 [7] -0.39769064 -0.19586058 -0.04807349 -0.01116326

## Should be the same as 'eigen_centrality' (but rescaled)
cor(eigen_centrality(kite)$vector, spectrum(kite)$vectors)

     [,1]
[1,]    1

## Smallest eigenvalues
spectrum(kite, which=list(pos="SM", howmany=2))$values

[1] -0.4043420  0.6403647

Examples for 'igraph::spectrum'

Eigenvalues and eigenvectors of the adjacency matrix of a graph