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Expose toFactorGraph to wrapper

release/4.3a0
Frank Dellaert 2023-01-13 08:26:32 -08:00
parent 906330f0e4
commit 681c75cea4
2 changed files with 22 additions and 37 deletions
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3
gtsam/hybrid/hybrid.i
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@ -141,6 +141,9 @@ class HybridBayesNet {
double logProbability(const gtsam::HybridValues& values) const;
double evaluate(const gtsam::HybridValues& values) const;
gtsam::HybridGaussianFactorGraph toFactorGraph(
const gtsam::VectorValues& measurements) const;
gtsam::HybridValues optimize() const;
gtsam::HybridValues sample(const gtsam::HybridValues &given) const;
gtsam::HybridValues sample() const;

56
python/gtsam/tests/test_HybridFactorGraph.py
View File

@ -152,23 +152,6 @@ class TestHybridGaussianFactorGraph(GtsamTestCase):
measurements.insert(Z(i), sample.at(Z(i)))
return measurements
@classmethod
def factor_graph_from_bayes_net(cls, bayesNet: HybridBayesNet,
sample: HybridValues):
"""Create a factor graph from the Bayes net with sampled measurements.
The factor graph is `P(x)P(n) ϕ(x, n; z0) ϕ(x, n; z1) ...`
and thus represents the same joint probability as the Bayes net.
"""
fg = HybridGaussianFactorGraph()
num_measurements = bayesNet.size() - 2
for i in range(num_measurements):
conditional = bayesNet.at(i).asMixture()
factor = conditional.likelihood(cls.measurements(sample, [i]))
fg.push_back(factor)
fg.push_back(bayesNet.at(num_measurements).asGaussian())
fg.push_back(bayesNet.at(num_measurements+1).asDiscrete())
return fg
@classmethod
def estimate_marginals(cls,
target,
@ -182,16 +165,14 @@ class TestHybridGaussianFactorGraph(GtsamTestCase):
for s in range(N):
proposed = proposal_density.sample() # sample from proposal
target_proposed = target(proposed) # evaluate target
# print(target_proposed, proposal_density.evaluate(proposed))
weight = target_proposed / proposal_density.evaluate(proposed)
# print weight:
# print(f"weight: {weight}")
marginals[proposed.atDiscrete(M(0))] += weight
# print marginals:
marginals /= marginals.sum()
return marginals
@unittest.skip
def test_tiny(self):
"""Test a tiny two variable hybrid model."""
# P(x0)P(mode)P(z0|x0,mode)
@ -202,12 +183,13 @@ class TestHybridGaussianFactorGraph(GtsamTestCase):
values = HybridValues()
values.insert(X(0), [5.0])
values.insert(M(0), 0) # low-noise, standard deviation 0.5
z0: float = 5.0
values.insert(Z(0), [z0])
measurements = gtsam.VectorValues()
measurements.insert(Z(0), [5.0])
values.insert(measurements)
def unnormalized_posterior(x):
"""Posterior is proportional to joint, centered at 5.0 as well."""
x.insert(Z(0), [z0])
x.insert(measurements)
return bayesNet.evaluate(x)
# Create proposal density on (x0, mode), making sure it has same mean:
@ -220,31 +202,31 @@ class TestHybridGaussianFactorGraph(GtsamTestCase):
# Estimate marginals using importance sampling.
marginals = self.estimate_marginals(target=unnormalized_posterior,
proposal_density=proposal_density)
# print(f"True mode: {values.atDiscrete(M(0))}")
# print(f"P(mode=0; Z) = {marginals[0]}")
# print(f"P(mode=1; Z) = {marginals[1]}")
print(f"True mode: {values.atDiscrete(M(0))}")
print(f"P(mode=0; Z) = {marginals[0]}")
print(f"P(mode=1; Z) = {marginals[1]}")
# Check that the estimate is close to the true value.
self.assertAlmostEqual(marginals[0], 0.74, delta=0.01)
self.assertAlmostEqual(marginals[1], 0.26, delta=0.01)
fg = self.factor_graph_from_bayes_net(bayesNet, values)
self.assertEqual(fg.size(), 3)
fg = bayesNet.toFactorGraph(measurements)
self.assertEqual(fg.size(), 4)
# Test elimination.
posterior = fg.eliminateSequential()
def true_posterior(x):
"""Posterior from elimination."""
x.insert(Z(0), [z0])
x.insert(measurements)
return posterior.evaluate(x)
# Estimate marginals using importance sampling.
marginals = self.estimate_marginals(target=true_posterior,
proposal_density=proposal_density)
# print(f"True mode: {values.atDiscrete(M(0))}")
# print(f"P(mode=0; z0) = {marginals[0]}")
# print(f"P(mode=1; z0) = {marginals[1]}")
print(f"True mode: {values.atDiscrete(M(0))}")
print(f"P(mode=0; z0) = {marginals[0]}")
print(f"P(mode=1; z0) = {marginals[1]}")
# Check that the estimate is close to the true value.
self.assertAlmostEqual(marginals[0], 0.74, delta=0.01)
@ -292,17 +274,17 @@ class TestHybridGaussianFactorGraph(GtsamTestCase):
# Estimate marginals using importance sampling.
marginals = self.estimate_marginals(target=unnormalized_posterior,
proposal_density=proposal_density)
# print(f"True mode: {values.atDiscrete(M(0))}")
# print(f"P(mode=0; Z) = {marginals[0]}")
# print(f"P(mode=1; Z) = {marginals[1]}")
print(f"True mode: {values.atDiscrete(M(0))}")
print(f"P(mode=0; Z) = {marginals[0]}")
print(f"P(mode=1; Z) = {marginals[1]}")
# Check that the estimate is close to the true value.
self.assertAlmostEqual(marginals[0], 0.23, delta=0.01)
self.assertAlmostEqual(marginals[1], 0.77, delta=0.01)
# Convert to factor graph using measurements.
fg = self.factor_graph_from_bayes_net(bayesNet, values)
self.assertEqual(fg.size(), 4)
fg = bayesNet.toFactorGraph(measurements)
self.assertEqual(fg.size(), 6)
# Calculate ratio between Bayes net probability and the factor graph:
expected_ratio = self.calculate_ratio(bayesNet, fg, values)