signed_blockmodel function

Blockmodeling for signed networks

Finds blocks of nodes with intra-positive and inter-negative edges

signed_blockmodel(g, k, alpha = 0.5, annealing = FALSE)

Arguments

• g: igraph object with a sign edge attribute.
• k: number of blocks
• alpha: see details
• annealing: logical. if TRUE, use simulated annealing (Default: FALSE)

Returns

numeric vector of block assignments and the associated criterion value

Details

The function minimizes P(C)=$\alpha$N+(1-$\alpha$)P, where N is the total number of negative ties within plus-sets and P be the total number of positive ties between plus-sets. This function implements the structural balance model. That is, all diagonal blocks are positive and off-diagonal blocks negative. For the generalized version see signed_blockmodel_general .

Examples

library(igraph)

g <- sample_islands_signed(10, 10, 1, 20)
clu <- signed_blockmodel(g, k = 10, alpha = 0.5)
table(clu$membership)
clu$criterion

# Using simulated annealing (less change of getting trapped in local optima)
data("tribes")
clu <- signed_blockmodel(tribes, k = 3, alpha = 0.5, annealing = TRUE)
table(clu$membership)
clu$criterion

References

Doreian, Patrick and Andrej Mrvar (2009). Partitioning signed social networks. Social Networks 31(1) 1-11

Author(s)

David Schoch