linkpred is a Python package for link prediction: given a network, linkpred provides a number of heuristics (known as predictors) that assess the likelihood of potential links in a future snapshot of the network.
While some predictors are fairly straightforward (e.g., if two people have a large number of mutual friends, it seems likely that eventually they will meet and become friends), others are more involved.
>>> import linkpred
>>> G = linkpred.read_network("examples/training.net")
11:49:00 - INFO - Reading file 'examples/training.net'...
11:49:00 - INFO - Successfully read file.
>>> len(G) # number of nodes
632
>>> simrank = linkpred.predictors.SimRank(G, only_new=True)
>>> simrank_results = simrank.predict(c=0.5)
>>> top = simrank_results.top(5)
>>> for authors, score in top.items():
... print authors, score
...
Tomizawa, H - Fujigaki, Y 0.188686630053
Shirabe, M - Hayashi, T 0.143866427916
Garfield, E - Fuseler, EA 0.148097050146
Persson, O - Larsen, IM 0.138516589957
Vanleeuwen, TN - Noyons, ECM 0.185040358711