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

Usage

is_weighted(graph)

Arguments

graph

The input graph.

Value

A logical scalar.

Details

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.

Author

Gabor Csardi csardi.gabor@gmail.com

Examples


g <- make_ring(10)
shortest_paths(g, 8, 2)
#> $vpath
#> $vpath[[1]]
#> + 5/10 vertices, from cd1470c:
#> [1]  8  9 10  1  2
#> 
#> 
#> $epath
#> NULL
#> 
#> $predecessors
#> NULL
#> 
#> $inbound_edges
#> NULL
#> 
E(g)$weight <- seq_len(ecount(g))
shortest_paths(g, 8, 2)
#> $vpath
#> $vpath[[1]]
#> + 7/10 vertices, from cd1470c:
#> [1] 8 7 6 5 4 3 2
#> 
#> 
#> $epath
#> NULL
#> 
#> $predecessors
#> NULL
#> 
#> $inbound_edges
#> NULL
#>