IndexEdgeTaggedGraph

IndexEdgeTaggedGraph[g] sets tags of edges in the graph g to their edge indices.

IndexEdgeTaggedGraph[g,r] sets tags of edges to r, r+1, ....

Examples

g = Graph[{1 -> 2, 2 -> 3, 3 -> 1}];
IndexEdgeTaggedGraph[g]

Please visit the official Wolfram Language Reference for more details.