From 4ff70141f8208db49f9deab3b51222eb66f63874 Mon Sep 17 00:00:00 2001
From: Varun Agrawal <varagrawal@gmail.com>
Date: Tue, 31 Dec 2024 00:10:37 -0500
Subject: [PATCH] use a TableFactor as the underlying data representation for
 DiscreteTableConditional since it provides a clean abstraction

---
 gtsam/discrete/DiscreteTableConditional.cpp | 17 ++++++-----------
 gtsam/discrete/DiscreteTableConditional.h   |  7 +++++--
 2 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/gtsam/discrete/DiscreteTableConditional.cpp b/gtsam/discrete/DiscreteTableConditional.cpp
index b09e2738f..a4fdcef5d 100644
--- a/gtsam/discrete/DiscreteTableConditional.cpp
+++ b/gtsam/discrete/DiscreteTableConditional.cpp
@@ -41,23 +41,21 @@ namespace gtsam {
 DiscreteTableConditional::DiscreteTableConditional(const size_t nrFrontals,
                                                    const TableFactor& f)
     : BaseConditional(nrFrontals, DecisionTreeFactor(f.discreteKeys(), ADT())),
-      sparse_table_((f / (*f.sum(nrFrontals))).sparseTable()) {
-  // sparse_table_ = sparse_table_.prune();
-}
+      table_(f / (*f.sum(nrFrontals))) {}
 
 /* ************************************************************************** */
 DiscreteTableConditional::DiscreteTableConditional(
     size_t nrFrontals, const DiscreteKeys& keys,
     const Eigen::SparseVector<double>& potentials)
     : BaseConditional(nrFrontals, keys, DecisionTreeFactor(keys, ADT())),
-      sparse_table_(potentials) {}
+      table_(TableFactor(keys, potentials)) {}
 
 /* ************************************************************************** */
 DiscreteTableConditional::DiscreteTableConditional(const TableFactor& joint,
                                                    const TableFactor& marginal)
     : BaseConditional(joint.size() - marginal.size(),
                       joint.discreteKeys() & marginal.discreteKeys(), ADT()),
-      sparse_table_((joint / marginal).sparseTable()) {}
+      table_(joint / marginal) {}
 
 /* ************************************************************************** */
 DiscreteTableConditional::DiscreteTableConditional(const TableFactor& joint,
@@ -71,8 +69,7 @@ DiscreteTableConditional::DiscreteTableConditional(const TableFactor& joint,
 /* ************************************************************************** */
 DiscreteTableConditional::DiscreteTableConditional(const Signature& signature)
     : BaseConditional(1, DecisionTreeFactor()),
-      sparse_table_(TableFactor(signature.discreteKeys(), signature.cpt())
-                        .sparseTable()) {}
+      table_(TableFactor(signature.discreteKeys(), signature.cpt())) {}
 
 /* ************************************************************************** */
 DiscreteTableConditional DiscreteTableConditional::operator*(
@@ -108,9 +105,7 @@ DiscreteTableConditional DiscreteTableConditional::operator*(
   // Finally, add parents to keys, in order
   for (auto&& dk : parents) discreteKeys.push_back(dk);
 
-  TableFactor a(this->discreteKeys(), this->sparse_table_),
-      b(other.discreteKeys(), other.sparse_table_);
-  TableFactor product = a * other;
+  TableFactor product = this->table_ * other.table();
   return DiscreteTableConditional(newFrontals.size(), product);
 }
 
@@ -128,7 +123,7 @@ void DiscreteTableConditional::print(const string& s,
     }
   }
   cout << "):\n";
-  // BaseFactor::print("", formatter);
+  table_.print("", formatter);
   cout << endl;
 }
 
diff --git a/gtsam/discrete/DiscreteTableConditional.h b/gtsam/discrete/DiscreteTableConditional.h
index 28e35277d..fae0c0761 100644
--- a/gtsam/discrete/DiscreteTableConditional.h
+++ b/gtsam/discrete/DiscreteTableConditional.h
@@ -29,13 +29,16 @@
 namespace gtsam {
 
 /**
- * Discrete Conditional Density which uses a SparseTable as the internal
+ * Discrete Conditional Density which uses a SparseVector as the internal
  * representation, similar to the TableFactor.
  *
  * @ingroup discrete
  */
 class GTSAM_EXPORT DiscreteTableConditional : public DiscreteConditional {
-  Eigen::SparseVector<double> sparse_table_;
+ private:
+  TableFactor table_;
+
+  typedef Eigen::SparseVector<double>::InnerIterator SparseIt;
 
  public:
   // typedefs needed to play nice with gtsam