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Select the k-Core of a Network

Source: R/wrangle-structure.R
select_k_core.Rd

The k-core is the maximal subgraph in which every node has degree at least k, found by repeatedly removing nodes of degree below k. Degree is the total degree, which is in-degree plus out-degree in a directed network. A self-loop adds 2 to the degree of its node.

Usage

select_k_core(x, k, keep_format = FALSE, directed = NULL)

Arguments

x

Network input.

k

A single non-negative whole number. The core number.

keep_format

Logical. If TRUE, a matrix, igraph, statnet network or tna input is returned in its own format. An edge-list data frame or a qgraph object is returned as a cograph_network with a cograph_no_format_roundtrip warning. Default FALSE returns a cograph_network.

directed

Logical or NULL. Directedness used to read the input. NULL (default) detects it from the input.

Value

A cograph_network holding the k-core, or the input format when keep_format = TRUE. When no node reaches coreness k, the result is an empty network and a warning is raised.

References

Seidman, S. B. (1983). Network structure and minimum degree. Social Networks, 5(3), 269–287.

See also

select_nodes, centrality

Examples

select_k_core(regulation_net, k = 2)
#> Cograph network: 10 nodes, 30 edges ( directed )
#> Source: matrix 
#>   Nodes (10): Explore, Plan, Monitor, Adapt, Reflect, Discuss, ... +4 more
#>   Edges: 30 / 90 (density: 33.3%)
#>   Weights: [0.050, 0.490]  |  mean: 0.265
#>   Strongest edges:
#>     Share -> Monitor  0.490
#>     Plan -> Evaluate  0.490
#>     Evaluate -> Adapt  0.430
#>     Synthesize -> Reflect  0.420
#>     Plan -> Discuss  0.400
#> Layout: none 
#>   Use as.data.frame() for the edge table, as.data.frame(what = "nodes") for the nodes.