discrete now has all logProbability and evaluate versions needed.

gtsam/discrete/DecisionTreeFactor.cpp

@@ -18,6 +18,7 @@
  */
 
 #include <gtsam/base/FastSet.h>
+#include <gtsam/hybrid/HybridValues.h>
 #include <gtsam/discrete/DecisionTreeFactor.h>
 #include <gtsam/discrete/DiscreteConditional.h>
 
@@ -56,6 +57,16 @@ namespace gtsam {
     }
   }
 
+  /* ************************************************************************ */
+  double DecisionTreeFactor::error(const DiscreteValues& values) const {
+    return -std::log(evaluate(values));
+  }
+  
+  /* ************************************************************************ */
+  double DecisionTreeFactor::error(const HybridValues& values) const {
+    return error(values.discrete());
+  }
+
   /* ************************************************************************ */
   double DecisionTreeFactor::safe_div(const double& a, const double& b) {
     // The use for safe_div is when we divide the product factor by the sum

gtsam/discrete/DecisionTreeFactor.h

@@ -34,6 +34,7 @@
 namespace gtsam {
 
   class DiscreteConditional;
+  class HybridValues;
 
   /**
    * A discrete probabilistic factor.
@@ -97,11 +98,20 @@ namespace gtsam {
     /// @name Standard Interface
     /// @{
 
-    /// Value is just look up in AlgebraicDecisionTree.
+    /// Calculate probability for given values `x`, 
+    /// is just look up in AlgebraicDecisionTree.
+    double evaluate(const DiscreteValues& values) const  {
+      return ADT::operator()(values);
+    }
+
+    /// Evaluate probability density, sugar.
     double operator()(const DiscreteValues& values) const override {
       return ADT::operator()(values);
     }
 
+    /// Calculate error for DiscreteValues `x`, is -log(probability).
+    double error(const DiscreteValues& values) const;
+
     /// multiply two factors
     DecisionTreeFactor operator*(const DecisionTreeFactor& f) const override {
       return apply(f, ADT::Ring::mul);
@@ -230,7 +240,17 @@ namespace gtsam {
     std::string html(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
                     const Names& names = {}) const override;
 
-    /// @}
+  /// @}
+  /// @name HybridValues methods.
+  /// @{
+
+  /**
+   * Calculate error for HybridValues `x`, is -log(probability)
+   * Simply dispatches to DiscreteValues version.
+   */
+  double error(const HybridValues& values) const override;
+
+  /// @}
 
    private:
     /** Serialization function */

gtsam/discrete/DiscreteConditional.h

@@ -18,9 +18,9 @@
 
 #pragma once
 
+#include <gtsam/inference/Conditional-inst.h>
 #include <gtsam/discrete/DecisionTreeFactor.h>
 #include <gtsam/discrete/Signature.h>
-#include <gtsam/inference/Conditional.h>
 
 #include <boost/make_shared.hpp>
 #include <boost/shared_ptr.hpp>
@@ -147,6 +147,11 @@ class GTSAM_EXPORT DiscreteConditional
   /// @name Standard Interface
   /// @{
 
+  /// Log-probability is just -error(x).
+  double logProbability(const DiscreteValues& x) const  {
+    return -error(x);
+  }
+
   /// print index signature only
   void printSignature(
       const std::string& s = "Discrete Conditional: ",
@@ -225,6 +230,21 @@ class GTSAM_EXPORT DiscreteConditional
   std::string html(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
                    const Names& names = {}) const override;
 
+
+  /// @}
+  /// @name HybridValues methods.
+  /// @{
+
+  /**
+   * Calculate log-probability log(evaluate(x)) for HybridValues `x`.
+   * This is actually just -error(x).
+   */
+  double logProbability(const HybridValues& x) const override {
+    return -error(x);
+  }
+
+  using DecisionTreeFactor::evaluate;
+
   /// @}
 
 #ifdef GTSAM_ALLOW_DEPRECATED_SINCE_V42

gtsam/discrete/tests/testDiscreteConditional.cpp

@@ -88,6 +88,29 @@ TEST(DiscreteConditional, constructors3) {
   EXPECT(assert_equal(expected, static_cast<DecisionTreeFactor>(actual)));
 }
 
+/* ****************************************************************************/
+// Test evaluate for a discrete Prior P(Asia).
+TEST(DiscreteConditional, PriorProbability) {
+  constexpr Key asiaKey = 0;
+  const DiscreteKey Asia(asiaKey, 2);
+  DiscreteConditional dc(Asia, "4/6");
+  DiscreteValues values{{asiaKey, 0}};
+  EXPECT_DOUBLES_EQUAL(0.4, dc.evaluate(values), 1e-9);
+}
+
+/* ************************************************************************* */
+// Check that error, logProbability, evaluate all work as expected.
+TEST(DiscreteConditional, probability) {
+  DiscreteKey C(2, 2), D(4, 2), E(3, 2);
+  DiscreteConditional C_given_DE((C | D, E) = "4/1 1/1 1/1 1/4");
+
+  DiscreteValues given {{C.first, 1}, {D.first, 0}, {E.first, 0}};
+  EXPECT_DOUBLES_EQUAL(0.2, C_given_DE.evaluate(given), 1e-9);
+  EXPECT_DOUBLES_EQUAL(0.2, C_given_DE(given), 1e-9);
+  EXPECT_DOUBLES_EQUAL(log(0.2), C_given_DE.logProbability(given), 1e-9);
+  EXPECT_DOUBLES_EQUAL(-log(0.2), C_given_DE.error(given), 1e-9);
+}
+
 /* ************************************************************************* */
 // Check calculation of joint P(A,B)
 TEST(DiscreteConditional, Multiply) {