def test_MPE(self):
"""Test maximum probable explanation (MPE): same as optimize."""
# Declare a bunch of keys
C, A, B = (0, 2), (1, 2), (2, 2)
# Create Factor graph
graph = DiscreteFactorGraph()
graph.add([C, A], "0.2 0.8 0.3 0.7")
graph.add([C, B], "0.1 0.9 0.4 0.6")
# We know MPE
mpe = DiscreteValues()
mpe[0] = 0
mpe[1] = 1
mpe[2] = 1
# Use maxProduct
dag = graph.maxProduct(OrderingType.COLAMD)
actualMPE = dag.argmax()
self.assertEqual(list(actualMPE.items()), list(mpe.items()))
# All in one
actualMPE2 = graph.optimize()
self.assertEqual(list(actualMPE2.items()), list(mpe.items()))
def test_sumProduct(self):
"""Test sumProduct."""
# Declare a bunch of keys
C, A, B = (0, 2), (1, 2), (2, 2)
# Create Factor graph
graph = DiscreteFactorGraph()
graph.add([C, A], "0.2 0.8 0.3 0.7")
graph.add([C, B], "0.1 0.9 0.4 0.6")
# We know MPE
mpe = DiscreteValues()
mpe[0] = 0
mpe[1] = 1
mpe[2] = 1
# Use default sumProduct
bayesNet = graph.sumProduct()
mpeProbability = bayesNet(mpe)
self.assertAlmostEqual(mpeProbability, 0.36) # regression
# Use sumProduct
for ordering_type in [
OrderingType.COLAMD, OrderingType.METIS, OrderingType.NATURAL,
OrderingType.CUSTOM
]:
bayesNet = graph.sumProduct(ordering_type)
self.assertEqual(bayesNet(mpe), mpeProbability)
def test_Asia(self):
"""Test full Asia example."""
asia = DiscreteBayesNet()
asia.add(Asia, "99/1")
asia.add(Smoking, "50/50")
asia.add(Tuberculosis, [Asia], "99/1 95/5")
asia.add(LungCancer, [Smoking], "99/1 90/10")
asia.add(Bronchitis, [Smoking], "70/30 40/60")
asia.add(Either, [Tuberculosis, LungCancer], "F T T T")
asia.add(XRay, [Either], "95/5 2/98")
asia.add(Dyspnea, [Either, Bronchitis], "9/1 2/8 3/7 1/9")
# Convert to factor graph
fg = DiscreteFactorGraph(asia)
# Create solver and eliminate
ordering = Ordering()
for j in range(8):
ordering.push_back(j)
chordal = fg.eliminateSequential(ordering)
expected2 = DiscreteDistribution(Bronchitis, "11/9")
self.gtsamAssertEquals(chordal.at(7), expected2)
# solve
actualMPE = fg.optimize()
expectedMPE = DiscreteValues()
for key in [
Asia, Dyspnea, XRay, Tuberculosis, Smoking, Either, LungCancer,
Bronchitis
]:
expectedMPE[key[0]] = 0
self.assertEqual(list(actualMPE.items()), list(expectedMPE.items()))
# Check value for MPE is the same
self.assertAlmostEqual(asia(actualMPE), fg(actualMPE))
# add evidence, we were in Asia and we have dyspnea
fg.add(Asia, "0 1")
fg.add(Dyspnea, "0 1")
# solve again, now with evidence
actualMPE2 = fg.optimize()
expectedMPE2 = DiscreteValues()
for key in [XRay, Tuberculosis, Either, LungCancer]:
expectedMPE2[key[0]] = 0
for key in [Asia, Dyspnea, Smoking, Bronchitis]:
expectedMPE2[key[0]] = 1
self.assertEqual(list(actualMPE2.items()), list(expectedMPE2.items()))
# now sample from it
chordal2 = fg.eliminateSequential(ordering)
actualSample = chordal2.sample()
self.assertEqual(len(actualSample), 8)
def test_evaluation(self):
"""Test constructing and evaluating a discrete factor graph."""
# Three keys
P1 = (0, 2)
P2 = (1, 2)
P3 = (2, 3)
# Create the DiscreteFactorGraph
graph = DiscreteFactorGraph()
# Add two unary factors (priors)
graph.add(P1, [0.9, 0.3])
graph.add(P2, "0.9 0.6")
# Add a binary factor
graph.add([P1, P2], "4 1 10 4")
# Instantiate Values
assignment = DiscreteValues()
assignment[0] = 1
assignment[1] = 1
# Check if graph evaluation works ( 0.3*0.6*4 )
self.assertAlmostEqual(.72, graph(assignment))
# Create a new test with third node and adding unary and ternary factor
graph.add(P3, "0.9 0.2 0.5")
keys = DiscreteKeys()
keys.push_back(P1)
keys.push_back(P2)
keys.push_back(P3)
graph.add(keys, "1 2 3 4 5 6 7 8 9 10 11 12")
# Below assignment selects the 8th index in the ternary factor table
assignment[0] = 1
assignment[1] = 0
assignment[2] = 1
# Check if graph evaluation works (0.3*0.9*1*0.2*8)
self.assertAlmostEqual(4.32, graph(assignment))
# Below assignment selects the 3rd index in the ternary factor table
assignment[0] = 0
assignment[1] = 1
assignment[2] = 0
# Check if graph evaluation works (0.9*0.6*1*0.9*4)
self.assertAlmostEqual(1.944, graph(assignment))
# Check if graph product works
product = graph.product()
self.assertAlmostEqual(1.944, product(assignment))
def test_optimize(self):
"""Test constructing and optizing a discrete factor graph."""
# Three keys
C = (0, 2)
B = (1, 2)
A = (2, 2)
# A simple factor graph (A)-fAC-(C)-fBC-(B)
# with smoothness priors
graph = DiscreteFactorGraph()
graph.add([A, C], "3 1 1 3")
graph.add([C, B], "3 1 1 3")
# Test optimization
expectedValues = DiscreteValues()
expectedValues[0] = 0
expectedValues[1] = 0
expectedValues[2] = 0
actualValues = graph.optimize()
self.assertEqual(list(actualValues.items()),
list(expectedValues.items()))