# diameter

0th

Percentile

##### 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

shortest.paths

##### Aliases
• diameter
• get.diameter
• farthest.nodes
##### 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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