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import numpy as np
import networkx as nx
import cascade_creation
from collections import Counter
from itertools import izip
def greedy_prediction(G, cascades):
"""
Returns estimated graph from Greedy algorithm in "Learning Epidemic ..."
"""
G_hat = cascade_creation.InfluenceGraph(max_proba=None)
G_hat.add_nodes_from(G.nodes())
for node in G_hat.nodes():
unaccounted = np.ones(len(cascades), dtype=bool)
for t, cascade in izip(xrange(len(cascades)), cascades):
if not cascade.infection_time(node) or \
cascade.infection_time(node)[0] == 0:
unaccounted[t] = False
while unaccounted.any():
tmp = [cascade for boolean, cascade in izip(unaccounted,
cascades) if boolean]
parents = Counter()
for cascade in tmp:
parents += cascade.candidate_infectors(node)
parent = parents.most_common(1)[0][0]
G_hat.add_edge(parent, node)
for t, cascade in izip(xrange(len(cascades)), cascades):
if (cascade.infection_time(parent) == \
[item - 1 for item in cascade.infection_time(node)]):
unaccounted[t] = False
return G_hat
def correctness_measure(G, G_hat):
"""
Measures correctness of estimated graph G_hat to ground truth G
"""
edges = set(G.edges())
edges_hat = set(G_hat.edges())
fp = edges_hat - edges
fn = edges - edges_hat
gp = edges | edges_hat
return fp, fn, gp
def test():
"""
unit test
"""
G = cascade_creation.InfluenceGraph(max_proba = .3)
G.erdos_init(n = 100, p = .1)
import time
t0 = time.time()
A = cascade_creation.generate_cascades(G, .1, 100)
G_hat = greedy_prediction(G, A)
fp, fn, gp = correctness_measure(G, G_hat)
print "False Positive: {}".format(len(fp))
print "False Negative: {}".format(len(fn))
print "Good Positives: {}".format(len(gp))
t1 = time.time()
print t1 - t0
if __name__=="__main__":
test()
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