update removeFixedValues to reintroduce a discrete factor on the removed value.

Author: varunagrawal

gtsam/hybrid/HybridSmoother.cpp

@@ -86,13 +86,28 @@ Ordering HybridSmoother::maybeComputeOrdering(
 }
 
 /* ************************************************************************* */
-void HybridSmoother::removeFixedValues(
+HybridGaussianFactorGraph HybridSmoother::removeFixedValues(
+    const HybridGaussianFactorGraph &graph,
     const HybridGaussianFactorGraph &newFactors) {
-  for (Key key : newFactors.discreteKeySet()) {
+  // Initialize graph
+  HybridGaussianFactorGraph updatedGraph(graph);
+
+  for (DiscreteKey dkey : newFactors.discreteKeys()) {
+    Key key = dkey.first;
     if (fixedValues_.find(key) != fixedValues_.end()) {
+      // Add corresponding discrete factor to reintroduce the information
+      std::vector<double> probabilities(
+          dkey.second, (1 - *marginalThreshold_) / dkey.second);
+      probabilities[fixedValues_[key]] = *marginalThreshold_;
+      DecisionTreeFactor dtf({dkey}, probabilities);
+      updatedGraph.push_back(dtf);
+
+      // Remove fixed value
       fixedValues_.erase(key);
     }
   }
+
+  return updatedGraph;
 }
 
 /* ************************************************************************* */
@@ -126,6 +141,11 @@ void HybridSmoother::update(const HybridNonlinearFactorGraph &newFactors,
             << std::endl;
 #endif
 
+  if (marginalThreshold_) {
+    // Remove fixed values for discrete keys which are introduced in newFactors
+    updatedGraph = removeFixedValues(updatedGraph, newFactors);
+  }
+
   Ordering ordering = this->maybeComputeOrdering(updatedGraph, given_ordering);
 
 #if GTSAM_HYBRID_TIMING
@@ -145,9 +165,6 @@ void HybridSmoother::update(const HybridNonlinearFactorGraph &newFactors,
   }
 #endif
 
-  // Remove fixed values for discrete keys which are introduced in newFactors
-  removeFixedValues(newFactors);
-
 #ifdef DEBUG_SMOOTHER
   // Print discrete keys in the bayesNetFragment:
   std::cout << "Discrete keys in bayesNetFragment: ";

gtsam/hybrid/HybridSmoother.h

@@ -145,8 +145,19 @@ class GTSAM_EXPORT HybridSmoother {
   Ordering maybeComputeOrdering(const HybridGaussianFactorGraph& updatedGraph,
                                 const std::optional<Ordering> givenOrdering);
 
-  /// Remove fixed discrete values for discrete keys introduced in `newFactors`.
-  void removeFixedValues(const HybridGaussianFactorGraph& newFactors);
+  /**
+   * @brief Remove fixed discrete values for discrete keys
+   * introduced in `newFactors`, and reintroduce discrete factors
+   * with marginalThreshold_ as the probability value.
+   *
+   * @param graph The factor graph with previous conditionals added in.
+   * @param newFactors The new factors added to the smoother,
+   * used to check if a fixed discrete value has been reintroduced.
+   * @return HybridGaussianFactorGraph
+   */
+  HybridGaussianFactorGraph removeFixedValues(
+      const HybridGaussianFactorGraph& graph,
+      const HybridGaussianFactorGraph& newFactors);
 };
 
 }  // namespace gtsam