fixed nodelist and edgelist reference problem

[jimixxperez]

a = pd.DataFrame([{'a': 1, 'c': 0}, {'a': 2, 'c': 2}, {'a': 3, 'c': 5}]) b = a b = b.loc[[0, 2]]

b => a c 0 1 0 2 3 5

a => a c 0 1 0 1 2 2 2 3 5