def test_best_path():
"""
Test viterbi path finding.
"""
for h in hypergraphs():
w = utils.random_log_viterbi_potentials(h)
path = ph.best_path(h, w)
nt.assert_not_equal(w.dot(path), 0.0)
valid_path(h, path)
same = False
for other_path in utils.all_paths(h):
assert w.dot(path) >= w.dot(other_path)
if path == other_path: same = True
assert same
def test_posteriors():
"Check the posteriors by enumeration."
for h in hypergraphs():
w = utils.random_inside_potentials(h)
marg = ph.compute_marginals(h, w)
paths = utils.all_paths(h)
m = defaultdict(lambda: 0.0)
total_score = 0.0
for path in paths:
path_score = w.dot(path)
total_score += path_score
for edge in path:
m[edge.id] += path_score
for edge in h.edges:
nt.assert_almost_equal(
marg[edge] / marg[h.root],
m[edge.id] / total_score, places=4)
chart = ph.inside(h, w)
nt.assert_almost_equal(chart[h.root], total_score, places=4)
def test_all():
s = simple_hypergraph()
for path in utils.all_paths(s):
valid_path(s, path)