How to change vertices of a graph to that are indexed from 0?
In Mathematica: ChangeVertices.
We can change it to the adjacency matrix A and from A to the graph. A faster solution?
Ho to get a permutation of vertices?
There is a method called relabel for that:
sage: g = Graph([('a','b'), ('b','c')])
sage: g.vertices()
['a', 'b', 'c']
sage: g.relabel()
sage: g.vertices()
[0, 1, 2]
sage: g.edges()
[(0, 1, None), (1, 2, None)]
To make sure of what it does, you may provide the permutation yourself as a dictionary:
sage: g = Graph([('a','b'), ('b','c')])
sage: g.relabel({'a':1,'b':2,'c':0})
sage: g.edges()
[(0, 2, None), (1, 2, None)]
See documentation of relabel method which has many options.
Maybe faster than that:
def ChangeVertices(g,di):
G=Graph()
for v in di.values():
G.add_vertex(v)
for e in g.edge_iterator():
G.add_edge(di[e[0]] if e[0] in di else e[0],di[e[1]] if e[1] in di else e[1])
return(G)
def GraphFromZero(g):
return(ChangeVertices(g,{v:i for i,v in enumerate(g.vertices())}))
Asked: 2020-05-02 17:01:38 +0100
Seen: 698 times
Last updated: May 02 '20
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