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:
in increasing order of number of nodes;
for a fixed number of nodes, in increasing order of the number of edges;
for fixed numbers of nodes and edges, in increasing order of the degree sequence, for example 111223 < 112222;
for fixed degree sequence, in increasing number of automorphisms.
See also
Other deterministic constructors:
graph_from_edgelist(),
graph_from_literal(),
make_(),
make_chordal_ring(),
make_circulant(),
make_empty_graph(),
make_full_citation_graph(),
make_full_graph(),
make_full_multipartite(),
make_graph(),
make_lattice(),
make_ring(),
make_star(),
make_tree(),
make_turan(),
make_wheel()
Examples
## Some randomly picked graphs from the atlas
graph_from_atlas(sample(0:1252, 1))
#> ── <igraph> Graph from the Atlas #464 ─────────────────────────────── 19c4eee ──
#> ℹ undirected
#> ℹ 7 vertices · 9 edges
#>
#> ── Attributes ──────────────────────────────────────────────────────────────────
#> → graph: name <chr>, n <dbl>
#>
#> ── Edges ───────────────────────────────────────────────────────────────────────
#> [1] 2 ─ 4 2 ─ 3 1 ─ 3 1 ─ 6 5 ─ 6 4 ─ 5 3 ─ 4 1 ─ 4 1 ─ 5
graph_from_atlas(sample(0:1252, 1))
#> ── <igraph> Graph from the Atlas #139 ─────────────────────────────── b55f492 ──
#> ℹ undirected
#> ℹ 6 vertices · 8 edges
#>
#> ── Attributes ──────────────────────────────────────────────────────────────────
#> → graph: name <chr>, n <dbl>
#>
#> ── Edges ───────────────────────────────────────────────────────────────────────
#> [1] 1 ─ 2 2 ─ 3 3 ─ 4 4 ─ 5 1 ─ 5 2 ─ 4 2 ─ 5 1 ─ 6