2015-11-12-152906.sagews

def graph_string(g, w = None):
    g.relabel()
    n = g.num_verts()
    m = g.num_edges()
    s = "{0} {1}\n".format(n, m)
    for x,y in g.edges(labels = False):
        s += "{0} {1}".format(x, y)
        if w:
            s += " {0}".format(w[(x, y)])
        s += "\n"
    return s

w=dict([(e, randint(1,10)) for e in g.edges(labels = False)])

w

{(0, 1): 9, (1, 2): 10, (6, 9): 10, (4, 9): 9, (6, 8): 1, (5, 7): 3, (2, 7): 6, (1, 6): 5, (3, 8): 4, (0, 5): 6, (0, 4): 5, (2, 3): 8, (3, 4): 5, (5, 8): 4, (7, 9): 2}

print graph_string(g, w)

10 15 0 1 9 0 4 5 0 5 6 1 2 10 1 6 5 2 3 8 2 7 6 3 4 5 3 8 4 4 9 9 5 7 3 5 8 4 6 8 1 6 9 10 7 9 2