# R igraph manual pages

Use this if you are using igraph from R

## 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.

### 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)


[Package igraph version 1.2.4 Index]