# diameter

From igraph v0.5.5-3
by Gabor Csardi

##### Diameter of a graph

The diameter of a graph is the length of the longest geodesic.

- Keywords
- graphs

##### Usage

```
diameter(graph, directed = TRUE, unconnected = TRUE, weights = NULL)
get.diameter (graph, directed = TRUE, unconnected = TRUE, weights = NULL)
farthest.nodes (graph, directed = TRUE, unconnected = TRUE, weights = NULL)
```

##### Arguments

- graph
- The graph to analyze.
- directed
- Logical, whether directed or undirected paths are to be considered. This is ignored for undirected graphs.
- unconnected
- Logical, what to do if the graph is unconnected. If FALSE, the function will return the largest possible diameter which is the number of vertices. If TRUE, the diameters of the connected components will be calculated and the largest one will b
- weights
- Optional positive weight vector for calculating
weighted distances. If the graph has a
`weight`

edge attribute, then this is used by default.

##### Details

The diameter is calculated by using a breadth-first search like method.

`get.diameter`

returns a path with the actual diameter. If there
are many shortest paths of the length of the diameter, then it returns
the first one found.

`farthest.points`

returns two vertex ids, the vertices which are
connected by the diameter path.

##### Value

- A numeric constant for
`diameter`

, a numeric vector for`get.diameter`

and a numeric vector of length two for`farthest.nodes`

.

##### concept

Diameter

##### See Also

##### Examples

```
g <- graph.ring(10)
g2 <- delete.edges(g, c(0,1,0,9))
diameter(g2, unconnected=TRUE)
diameter(g2, unconnected=FALSE)
## Weighted diameter
set.seed(1)
g <- graph.ring(10)
E(g)$weight <- sample(seq_len(ecount(g)))
diameter(g)
get.diameter(g)
diameter(g, weights=NA)
get.diameter(g, weights=NA)
```

*Documentation reproduced from package igraph, version 0.5.5-3, License: GPL (>= 2)*

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