Bridge metrics for nodes across communities

Computes bridge centrality measures for nodes with an assigned community. This function is used internally by mixMN() and multimixMN(). Specifically, the function computes bridge strength as the sum of absolute edge weights connecting a node to nodes in other communities; bridge expected influence of order one (EI1) as the signed sum of direct connections to nodes in other communities; bridge expected influence of order two (EI2) as the signed influence that propagates indirectly to nodes in other communities via one intermediate neighbor (i.e., through paths of length two); bridge betweenness as the number of times a node lies on shortest paths between nodes belonging to different communities; and bridge closeness as the inverse of the mean shortest-path distance to nodes in other communities.

Usage

bridge_metrics(g, membership)

Arguments

g

An igraph object with edge attribute weight.

membership

Named vector/factor of community labels for a subset of nodes (names must match V(g)$name).

Value

A data.frame with columns: node, community, bridge_strength, bridge_ei1, bridge_ei2, bridge_betweenness, bridge_closeness.

Details

Bridge betweenness and closeness are computed on the positive-weight subgraph only, with weights converted to distances as \(d = 1/w\).

References

Jones, P. J. (2025). networktools: Tools for identifying important nodes in networks. R package version 1.6.1. https://github.com/paytonjjones/networktools

Jones, P. J., Ma, R., & McNally, R. J. (2021). Bridge Centrality: A Network Approach to Understanding Comorbidity. Multivariate Behavioral Research, 56(2), 353–367. doi:10.1080/00273171.2019.1614898