If you wish to iterate through all the isomorphism types of graphs, type, for example:
sage: for g in graphs(4): ... print g.spectrum() [0.0, 0.0, 0.0, 0.0] ... [-1.0, -1.0, -1.0, 3.0]
For some commonly used graphs to play with, type
sage: graphs.[tab] # not tested
and hit tab. Most of these graphs come with their own custom plot, so you can see how people usually visualize these graphs.
sage: G = graphs.PetersenGraph() sage: G.plot().show() # or G.show() sage: G.degree_histogram() [0, 0, 0, 10] sage: G.adjacency_matrix() [0 1 0 0 1 1 0 0 0 0] [1 0 1 0 0 0 1 0 0 0] [0 1 0 1 0 0 0 1 0 0] [0 0 1 0 1 0 0 0 1 0] [1 0 0 1 0 0 0 0 0 1] [1 0 0 0 0 0 0 1 1 0] [0 1 0 0 0 0 0 0 1 1] [0 0 1 0 0 1 0 0 0 1] [0 0 0 1 0 1 1 0 0 0] [0 0 0 0 1 0 1 1 0 0]
sage: S = G.subgraph([0,1,2,3]) sage: S.plot().show() # or S.show() sage: S.density() 1/2
sage: G = GraphDatabase() sage: L = G.get_list(num_vertices=7, diameter=5) sage: graphs_list.show_graphs(L)
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