verify_with_igraph: Verify Against igraph

In cograph: Analysis and Visualization of Complex Networks

Verify Against igraph

Description

Confirms numerical match with igraph's contract_vertices + simplify.

Usage

verify_with_igraph(x, clusters, method = "sum", type = "raw")

verify_igraph(x, clusters, method = "sum", type = "raw")

Arguments

x	Adjacency matrix
clusters	Cluster specification (see csum)
method	Aggregation method. Default "sum".
type	Normalization type. Defaults to "raw" for igraph compatibility.

Value

A list with components our_result (cograph's macro weight matrix), igraph_result (igraph's contract() + simplify() matrix), matches (logical: do the off-diagonals agree to within 1e-10?) and difference (the all.equal() report when they do not, otherwise NULL). Returns NULL with a message if igraph is not installed.

Examples

if (requireNamespace("igraph", quietly = TRUE)) {
  mat <- matrix(runif(100), 10, 10)
  diag(mat) <- 0
  rownames(mat) <- colnames(mat) <- LETTERS[1:10]
  clusters <- c(1,1,1,2,2,2,3,3,3,3)
  verify_igraph(mat, clusters)
}

cograph documentation built on Sept. 30, 2026, 5:08 p.m.