This method relabels the vertices of a graph of class MixedGraph according to their indices. The method indexes from 0 to the number of vertices minus one. This is an adaptation of the method indexLabelGraph.
i1 : G= mixedGraph(graph{{a,b},{b,c}},digraph {{a,d},{c,e},{f,g}},bigraph {{d,e}})
o1 = MixedGraph{Bigraph => Bigraph{d => {e}}}
e => {d}
Digraph => Digraph{a => {d}}
c => {e}
d => {}
e => {}
f => {g}
g => {}
Graph => Graph{a => {b} }
b => {a, c}
c => {b}
o1 : MixedGraph