Replaces each group of nodes with a single node whose edges aggregate the
edges of its members. The counterpart of igraph::contract() and
tidygraph's to_contracted(), and the network form of what
summarize_clusters() computes inside an analysis object.
Usage
contract_nodes(
x,
groups,
weight = c("sum", "mean", "max", "min"),
loops = FALSE,
keep_format = FALSE,
directed = NULL
)Arguments
- x
Network input.
- groups
Group assignment. Either a vector with one entry per node (in node order), or a named list mapping group name to node labels.
- weight
How to aggregate the weights of the edges that fall between two groups:
"sum"(default),"mean","max"or"min".- loops
Logical. Keep the within-group edges as self-loops on the contracted node. Default FALSE.
- keep_format
Logical. Return the input format when TRUE.
- directed
Logical or NULL. If NULL (default), auto-detect.
Value
A cograph_network with one node per group, labeled by group
name, or the input format when keep_format = TRUE.
Examples
adj <- matrix(c(0, 1, 1, 0,
1, 0, 0, 1,
1, 0, 0, 1,
0, 1, 1, 0), 4, 4, byrow = TRUE)
rownames(adj) <- colnames(adj) <- c("A", "B", "C", "D")
contract_nodes(adj, groups = c("left", "left", "right", "right"))
#> Cograph network: 2 nodes, 1 edges ( undirected )
#> Source: matrix
#> Nodes (2): left, right
#> Edges: 1 / 1 (density: 100.0%)
#> Weights: [2.000, 2.000] | mean: 2.000
#> Strongest edges:
#> left -- right 2.000
#> Layout: none
#> Use as.data.frame() for the edge table, as.data.frame(what = "nodes") for the nodes.