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

## 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`degree()`

is called. If this is`NA`

, then no edge weights are used (even if the graph has a`weight`

edge attribute).

## References

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

## See also

`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()`

## Author

Gabor Csardi csardi.gabor@gmail.com