add TableFactor constructor from DiscreteConditional

gtsam/discrete/DecisionTreeFactor.cpp

@@ -181,6 +181,15 @@ namespace gtsam {
     return result;
   }
 
+  /* ************************************************************************ */
+  std::vector<double> DecisionTreeFactor::probabilities() const {
+    std::vector<double> probs;
+    for (auto&& [key, value] : enumerate()) {
+      probs.push_back(value);
+    }
+    return probs;
+  }
+
   /* ************************************************************************ */
   DiscreteKeys DecisionTreeFactor::discreteKeys() const {
     DiscreteKeys result;
@@ -306,11 +315,10 @@ namespace gtsam {
 
     // Get the probabilities in the decision tree so we can threshold.
     std::vector<double> probabilities;
-    this->visitLeaf([&](const Leaf& leaf) {
-      size_t nrAssignments = leaf.nrAssignments();
-      double prob = leaf.constant();
-      probabilities.insert(probabilities.end(), nrAssignments, prob);
-    });
+    // NOTE(Varun) this is potentially slow due to the cartesian product
+    for (auto&& [assignment, prob] : this->enumerate()) {
+      probabilities.push_back(prob);
+    }
 
     // The number of probabilities can be lower than max_leaves
     if (probabilities.size() <= N) {

gtsam/discrete/DecisionTreeFactor.h

@@ -181,6 +181,9 @@ namespace gtsam {
     /// Enumerate all values into a map from values to double.
     std::vector<std::pair<DiscreteValues, double>> enumerate() const;
 
+    /// Get all the probabilities in order of assignment values
+    std::vector<double> probabilities() const;
+
     /// Return all the discrete keys associated with this factor.
     DiscreteKeys discreteKeys() const;
 

gtsam/discrete/TableFactor.cpp

@@ -13,11 +13,12 @@
  * @file TableFactor.cpp
  * @brief discrete factor
  * @date May 4, 2023
- * @author Yoonwoo Kim
+ * @author Yoonwoo Kim, Varun Agrawal
  */
 
 #include <gtsam/base/FastSet.h>
 #include <gtsam/discrete/DecisionTreeFactor.h>
+#include <gtsam/discrete/DiscreteConditional.h>
 #include <gtsam/discrete/TableFactor.h>
 #include <gtsam/hybrid/HybridValues.h>
 
@@ -56,6 +57,10 @@ TableFactor::TableFactor(const DiscreteKeys& dkeys,
   sort(sorted_dkeys_.begin(), sorted_dkeys_.end());
 }
 
+/* ************************************************************************ */
+TableFactor::TableFactor(const DiscreteConditional& c)
+    : TableFactor(c.discreteKeys(), c.probabilities()) {}
+
 /* ************************************************************************ */
 Eigen::SparseVector<double> TableFactor::Convert(
     const std::vector<double>& table) {

gtsam/discrete/TableFactor.h

@@ -12,7 +12,7 @@
 /**
  * @file TableFactor.h
  * @date May 4, 2023
- * @author Yoonwoo Kim
+ * @author Yoonwoo Kim, Varun Agrawal
  */
 
 #pragma once
@@ -32,6 +32,7 @@
 
 namespace gtsam {
 
+class DiscreteConditional;
 class HybridValues;
 
 /**
@@ -75,7 +76,7 @@ class GTSAM_EXPORT TableFactor : public DiscreteFactor {
    * @brief Return ith key in keys_ as a DiscreteKey
    * @param i ith key in keys_
    * @return DiscreteKey
-   * */ 
+   */
   DiscreteKey discreteKey(size_t i) const {
     return DiscreteKey(keys_[i], cardinalities_.at(keys_[i]));
   }
@@ -142,6 +143,9 @@ class GTSAM_EXPORT TableFactor : public DiscreteFactor {
   TableFactor(const DiscreteKey& key, const std::vector<double>& row)
       : TableFactor(DiscreteKeys{key}, row) {}
 
+  /** Construct from a DiscreteConditional type */
+  explicit TableFactor(const DiscreteConditional& c);
+
   /// @}
   /// @name Testable
   /// @{

gtsam/discrete/tests/testTableFactor.cpp

@@ -93,7 +93,8 @@ void printTime(map<double, pair<chrono::microseconds, chrono::microseconds>>
   for (auto&& kv : measured_time) {
     cout << "dropout: " << kv.first
          << " | TableFactor time: " << kv.second.first.count()
-         << " | DecisionTreeFactor time: " << kv.second.second.count() << endl;
+         << " | DecisionTreeFactor time: " << kv.second.second.count() <<
+         endl;
   }
 }
 
@@ -124,6 +125,13 @@ TEST(TableFactor, constructors) {
 
   // Assert that error = -log(value)
   EXPECT_DOUBLES_EQUAL(-log(f1(values)), f1.error(values), 1e-9);
+
+  // Construct from DiscreteConditional
+  DiscreteConditional conditional(X | Y = "1/1 2/3 1/4");
+  TableFactor f4(conditional);
+  // Manually constructed via inspection and comparison to DecisionTreeFactor
+  TableFactor expected(X & Y, "0.5 0.4 0.2 0.5 0.6 0.8");
+  EXPECT(assert_equal(expected, f4));
 }
 
 /* ************************************************************************* */
@@ -156,7 +164,8 @@ TEST(TableFactor, multiplication) {
 /* ************************************************************************* */
 // Benchmark which compares runtime of multiplication of two TableFactors
 // and two DecisionTreeFactors given sparsity from dense to 90% sparsity.
-TEST(TableFactor, benchmark) {
+// NOTE: Enable to run.
+TEST_DISABLED(TableFactor, benchmark) {
   DiscreteKey A(0, 5), B(1, 2), C(2, 5), D(3, 2), E(4, 5), F(5, 2), G(6, 3),
       H(7, 2), I(8, 5), J(9, 7), K(10, 2), L(11, 3);