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graph_from_atlas() creates graphs from the book ‘An Atlas of Graphs’ by Roland C. Read and Robin J. Wilson. The atlas contains all undirected graphs with up to seven vertices, numbered from 0 up to 1252. The graphs are listed:

  1. in increasing order of number of nodes;

  2. for a fixed number of nodes, in increasing order of the number of edges;

  3. for fixed numbers of nodes and edges, in increasing order of the degree sequence, for example 111223 < 112222;

  4. for fixed degree sequence, in increasing number of automorphisms.

Usage

graph_from_atlas(n)

atlas(...)

Arguments

n

The id of the graph to create.

...

Passed to graph_from_atlas().

Value

An igraph graph.

Examples

## Some randomly picked graphs from the atlas
graph_from_atlas(sample(0:1252, 1))
#> IGRAPH 7c0690b U--- 7 7 -- Graph from the Atlas #303
#> + attr: name (g/c), n (g/n)
#> + edges from 7c0690b:
#> [1] 2--5 2--4 3--4 3--5 1--3 2--3 1--7
graph_from_atlas(sample(0:1252, 1))
#> IGRAPH 2c3bffe U--- 7 10 -- Graph from the Atlas #648
#> + attr: name (g/c), n (g/n)
#> + edges from 2c3bffe:
#>  [1] 1--2 2--3 3--4 4--5 1--5 1--6 5--6 3--6 4--6 5--7