# strength: Strength or weighted vertex degree In igraph: Network Analysis and Visualization

 strength R Documentation

## Strength or weighted vertex degree

### Description

Summing up the edge weights of the adjacent edges for each vertex.

### Usage

``````strength(
graph,
vids = V(graph),
mode = c("all", "out", "in", "total"),
loops = TRUE,
weights = NULL
)
``````

### Arguments

 `graph` The input graph. `vids` The vertices for which the strength will be calculated. `mode` Character string, “out” for out-degree, “in” for in-degree or “all” for the sum of the two. For undirected graphs this argument is ignored. `loops` Logical; whether the loop edges are also counted. `weights` Weight vector. If the graph has a `weight` edge attribute, then this is used by default. If the graph does not have a `weight` edge attribute and this argument is `NULL`, then a warning is given and `degree()` is called.

### Value

A numeric vector giving the strength of the vertices.

### Author(s)

Gabor Csardi csardi.gabor@gmail.com

### References

Alain Barrat, Marc Barthelemy, Romualdo Pastor-Satorras, Alessandro Vespignani: The architecture of complex weighted networks, Proc. Natl. Acad. Sci. USA 101, 3747 (2004)

`degree()` for the unweighted version.

Centrality measures `alpha_centrality()`, `betweenness()`, `closeness()`, `diversity()`, `eigen_centrality()`, `harmonic_centrality()`, `hub_score()`, `page_rank()`, `power_centrality()`, `spectrum()`, `subgraph_centrality()`

### Examples

``````
g <- make_star(10)
E(g)\$weight <- seq(ecount(g))
strength(g)
strength(g, mode = "out")
strength(g, mode = "in")

# No weights, a warning is given
g <- make_ring(10)
strength(g)
``````

igraph documentation built on Aug. 10, 2023, 9:08 a.m.