def check_best_path(graph, max_potentials):
"""
Test viterbi path finding.
"""
path = pydecode.best_path(graph, max_potentials)
nt.assert_not_equal(max_potentials.T * path.v, 0.0)
utils.valid_path(graph, path)
same = False
for other_path in utils.all_paths(graph):
assert max_potentials.T * path.v >= max_potentials.T * other_path.v
if path == other_path:
same = True
assert same
def check_posteriors(graph, pot):
"""
Check the posteriors by enumeration.
"""
node_marg = pydecode.marginals(graph, pot)
paths = utils.all_paths(graph)
m = defaultdict(lambda: 0.0)
total_score = 0.0
for path in paths:
#path_score = prod([pot[edge.id] for edge in path.edges])
path_score = np.exp(np.log(pot.T) * path.v)
total_score += path_score
for edge in path:
m[edge.id] += path_score