Added conditional markdown formatter

gtsam/discrete/DiscreteConditional.cpp

@@ -222,6 +222,46 @@ size_t DiscreteConditional::sample(const DiscreteValues& parentsValues) const {
   return distribution(rng);
 }
 
-/* ******************************************************************************** */
+/* ************************************************************************* */
+std::string DiscreteConditional::_repr_markdown_(
+    const KeyFormatter& keyFormatter) const {
+  std::stringstream ss;
+
+  // Print out header and construct argument for `cartesianProduct`.
+  // TODO(dellaert): examine why we can't use "for (auto key: frontals())"
+  std::vector<std::pair<Key, size_t>> pairs;
+  ss << "|";
+  const_iterator it;
+  for (it = beginParents(); it != endParents(); ++it) {
+    auto key = *it;
+    ss << keyFormatter(key) << "|";
+    pairs.emplace_back(key, cardinalities_.at(key));
+  }
+  for (it = beginFrontals(); it != endFrontals(); ++it) {
+    auto key = *it;
+    ss << keyFormatter(key) << "|";
+    pairs.emplace_back(key, cardinalities_.at(key));
+  }
+  ss << "value|\n";
+
+  // Print out separator with alignment hints.
+  ss << "|";
+  for (size_t j = 0; j < size(); j++) ss << ":-:|";
+  ss << ":-:|\n";
+
+  // Print out all rows.
+  std::vector<std::pair<Key, size_t>> rpairs(pairs.rbegin(), pairs.rend());
+  const auto assignments = cartesianProduct(rpairs);
+  for (const auto& a : assignments) {
+    ss << "|";
+    for (it = beginParents(); it != endParents(); ++it) ss << a.at(*it) << "|";
+    for (it = beginFrontals(); it != endFrontals(); ++it)
+      ss << "*" << a.at(*it) << "*|";
+    ss << operator()(a) << "|\n";
+  }
+  return ss.str();
+}
+/* ********************************************************************************
+ */
 
 }// namespace

gtsam/discrete/DiscreteConditional.h

@@ -167,7 +167,14 @@ public:
   void sampleInPlace(DiscreteValues* parentsValues) const;
 
   /// @}
+  /// @name Wrapper support
+  /// @{
 
+  /// Render as markdown table.
+  std::string _repr_markdown_(
+      const KeyFormatter& keyFormatter = DefaultKeyFormatter) const;
+
+  /// @}
 };
 // DiscreteConditional
 

gtsam/discrete/tests/testDiscreteConditional.cpp

@@ -101,9 +101,50 @@ TEST(DiscreteConditional, Combine) {
   c.push_back(boost::make_shared<DiscreteConditional>(A | B = "1/2 2/1"));
   c.push_back(boost::make_shared<DiscreteConditional>(B % "1/2"));
   DecisionTreeFactor factor(A & B, "0.111111 0.444444 0.222222 0.222222");
-  DiscreteConditional actual(2, factor);
-  auto expected = DiscreteConditional::Combine(c.begin(), c.end());
-  EXPECT(assert_equal(*expected, actual, 1e-5));
+  DiscreteConditional expected(2, factor);
+  auto actual = DiscreteConditional::Combine(c.begin(), c.end());
+  EXPECT(assert_equal(expected, *actual, 1e-5));
+}
+
+/* ************************************************************************* */
+// TEST(DiscreteConditional, Combine2) {
+//   DiscreteKey A(0, 3), B(1, 2), C(2, 2);
+//   vector<DiscreteConditional::shared_ptr> c;
+//   auto P = {B, C};
+//   c.push_back(boost::make_shared<DiscreteConditional>(A, P, "1/2 2/1 1/2 2/1"));
+//   c.push_back(boost::make_shared<DiscreteConditional>(B | C = "1/2"));
+//   auto actual = DiscreteConditional::Combine(c.begin(), c.end());
+//   GTSAM_PRINT(*actual);
+// }
+
+/* ************************************************************************* */
+// Check markdown representation looks as expected.
+TEST(DiscreteConditional, markdown) {
+  DiscreteKey A(2, 2), B(1, 2), C(0, 3);
+  DiscreteConditional conditional(A, {B, C}, "0/1 1/3  1/1 3/1  0/1 1/0");
+  EXPECT_LONGS_EQUAL(A.first, *(conditional.beginFrontals()));
+  EXPECT_LONGS_EQUAL(B.first, *(conditional.beginParents()));
+  EXPECT(conditional.endParents() == conditional.end());
+  EXPECT(conditional.endFrontals() == conditional.beginParents());
+  string expected =
+      "|B|C|A|value|\n"
+      "|:-:|:-:|:-:|:-:|\n"
+      "|0|0|*0*|0|\n"
+      "|0|0|*1*|1|\n"
+      "|0|1|*0*|0.25|\n"
+      "|0|1|*1*|0.75|\n"
+      "|0|2|*0*|0.5|\n"
+      "|0|2|*1*|0.5|\n"
+      "|1|0|*0*|0.75|\n"
+      "|1|0|*1*|0.25|\n"
+      "|1|1|*0*|0|\n"
+      "|1|1|*1*|1|\n"
+      "|1|2|*0*|1|\n"
+      "|1|2|*1*|0|\n";
+  vector<string> names{"C", "B", "A"};
+  auto formatter = [names](Key key) { return names[key]; };
+  string actual = conditional._repr_markdown_(formatter);
+  EXPECT(actual == expected);
 }
 
 /* ************************************************************************* */