Sage code for generating random weighted undirected graph

weightedgraphs.py

## Generates a random weighted undirected graph. 
## n = number of nodes
## p = probability that two nodes are adjacent; must be between 0 and 1. 
## lower_weight and upper_weight = lower and upper edge weights, respectively. If left out, the defaults are 1 and 100. 
##
## Examples of usage: 
##  g = random_weighted_graph(20, 0.5) <-- Uses default lower and upper weights of 1 and 100. 
##  h = random_weighted_graph(10, 0.35, 5, 50) <-- Weights will be integers between 5 and 50. 
##  g.show(edge_labels = True) <-- Include the argument to display the weights
##  h.show() <-- leave the argument out to hide the weights

def random_weighted_graph(n, p, lower_weight = 1, upper_weight = 100): 
    import random
    g = graphs.RandomGNP(n,p)
    m = g.num_edges()
    weights = [random.randint(lower_weight, upper_weight) for r in xrange(m)]
    uw_edges = g.edges()
    
    # Create weighted graph edge list 
    w_edges = [(uw_edges[i][0], uw_edges[i][1], weights[i]) for i in xrange(m)]
    
    return Graph(w_edges, weighted = True)