test_HybridBayesNet.py

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"""
GTSAM Copyright 2010-2022, Georgia Tech Research Corporation,
Atlanta, Georgia 30332-0415
All Rights Reserved
 
See LICENSE for the license information
 
Unit tests for Hybrid Values.
Author: Frank Dellaert
"""
# pylint: disable=invalid-name, no-name-in-module, no-member
 
import math
import unittest
 
import numpy as np
from gtsam.symbol_shorthand import A, X
from gtsam.utils.test_case import GtsamTestCase
 
from gtsam import (DiscreteConditional, DiscreteValues,
                   GaussianConditional, HybridBayesNet,
                   HybridGaussianConditional, HybridValues, VectorValues,
                   noiseModel)
 
 
class TestHybridBayesNet(GtsamTestCase):
    """Unit tests for HybridValues."""
 
    def test_evaluate(self):
        """Test evaluate for a hybrid Bayes net P(X0|X1) P(X1|Asia) P(Asia)."""
        asiaKey = A(0)
        Asia = (asiaKey, 2)
 
        # Create the continuous conditional
        I_1x1 = np.eye(1)
        conditional = GaussianConditional.FromMeanAndStddev(
            X(0), 2 * I_1x1, X(1), [-4], 5.0)
 
        # Create the noise models
        model0 = noiseModel.Diagonal.Sigmas([2.0])
        model1 = noiseModel.Diagonal.Sigmas([3.0])
 
        # Create the conditionals
        conditional0 = GaussianConditional(X(1), [5], I_1x1, model0)
        conditional1 = GaussianConditional(X(1), [2], I_1x1, model1)
 
        # Create hybrid Bayes net.
        bayesNet = HybridBayesNet()
        bayesNet.push_back(conditional)
        bayesNet.push_back(
            HybridGaussianConditional(Asia, [conditional0, conditional1]))
        bayesNet.push_back(DiscreteConditional(Asia, "99/1"))
 
        # Create values at which to evaluate.
        values = HybridValues()
        continuous = VectorValues()
        continuous.insert(X(0), [-6])
        continuous.insert(X(1), [1])
        values.insert(continuous)
        discrete = DiscreteValues()
        discrete[asiaKey] = 0
        values.insert(discrete)
 
        conditionalProbability = conditional.evaluate(values.continuous())
        mixtureProbability = conditional0.evaluate(values.continuous())
        self.assertAlmostEqual(conditionalProbability * mixtureProbability *
                               0.99,
                               bayesNet.evaluate(values),
                               places=5)
 
        # Check logProbability
        self.assertAlmostEqual(bayesNet.logProbability(values),
                               math.log(bayesNet.evaluate(values)))
 
        # Check invariance for all conditionals:
        self.check_invariance(bayesNet.at(0).asGaussian(), continuous)
        self.check_invariance(bayesNet.at(0).asGaussian(), values)
        self.check_invariance(bayesNet.at(0), values)
 
        self.check_invariance(bayesNet.at(1), values)
 
        self.check_invariance(bayesNet.at(2).asDiscrete(), discrete)
        self.check_invariance(bayesNet.at(2).asDiscrete(), values)
        self.check_invariance(bayesNet.at(2), values)
 
    def check_invariance(self, conditional, values):
        """Check invariance for given conditional."""
        probability = conditional.evaluate(values)
        self.assertTrue(probability >= 0.0)
        logProb = conditional.logProbability(values)
        self.assertAlmostEqual(probability, np.exp(logProb))
        expected = -(conditional.negLogConstant() + conditional.error(values))
        self.assertAlmostEqual(logProb, expected)
 
 
if __name__ == "__main__":
    unittest.main()