def write(self, fname):
""" writes self to txtfile.
If network is undirected, edge-pairs appear twice.
"""
t_edges = []
for i in range(len(self)):
print "extracting edges ", i
indices = zip(self[i].nonzero()[0], self[i].nonzero()[1])
to_add = [(u, v, i) for u, v in indices]
t_edges.extend(to_add)
t_edges_clean = t_edges[:]
if not self.is_directed:
print "cleaning edgelist..."
for (u, v, d) in t_edges_clean:
if (v, u, d) in t_edges_clean:
t_edges_clean.remove((v, u, d))
gwh.write_array(t_edges_clean, fname)
return
