Use this if you are using igraph from R

is_weighted {igraph} | R Documentation |

In weighted graphs, a real number is assigned to each (directed or undirected) edge.

```
is_weighted(graph)
```

`graph` |
The input graph. |

In igraph edge weights are represented via an edge attribute, called
‘weight’. The `is_weighted`

function only checks that such an
attribute exists. (It does not even checks that it is a numeric edge
attribute.)

Edge weights are used for different purposes by the different functions. E.g. shortest path functions use it as the cost of the path; community finding methods use it as the strength of the relationship between two vertices, etc. Check the manual pages of the functions working with weighted graphs for details.

A logical scalar.

Gabor Csardi csardi.gabor@gmail.com

```
g <- make_ring(10)
shortest_paths(g, 8, 2)
E(g)$weight <- seq_len(ecount(g))
shortest_paths(g, 8, 2)
```

[Package *igraph* version 1.3.1 Index]