diff --git a/gtsam/discrete/DecisionTreeFactor.cpp b/gtsam/discrete/DecisionTreeFactor.cpp
index 75018cf928..4f3e3f7f14 100644
--- a/gtsam/discrete/DecisionTreeFactor.cpp
+++ b/gtsam/discrete/DecisionTreeFactor.cpp
@@ -179,9 +179,9 @@ namespace gtsam {
   }
 
   /* ************************************************************************* */
-  std::string DecisionTreeFactor::markdown(
-      const KeyFormatter& keyFormatter) const {
-    std::stringstream ss;
+  string DecisionTreeFactor::markdown(const KeyFormatter& keyFormatter,
+                                      const Names& names) const {
+    stringstream ss;
 
     // Print out header and construct argument for `cartesianProduct`.
     ss << "|";
@@ -200,7 +200,10 @@ namespace gtsam {
     for (const auto& kv : rows) {
       ss << "|";
       auto assignment = kv.first;
-      for (auto& key : keys()) ss << assignment.at(key) << "|";
+      for (auto& key : keys()) {
+        size_t index = assignment.at(key);
+        ss << Translate(names, key, index) << "|";
+      }
       ss << kv.second << "|\n";
     }
     return ss.str();
diff --git a/gtsam/discrete/DecisionTreeFactor.h b/gtsam/discrete/DecisionTreeFactor.h
index 46509db822..f8832c2237 100644
--- a/gtsam/discrete/DecisionTreeFactor.h
+++ b/gtsam/discrete/DecisionTreeFactor.h
@@ -192,9 +192,15 @@ namespace gtsam {
     std::string dot(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
                     bool showZero = true) const;
 
-    /// Render as markdown table.
-    std::string markdown(
-        const KeyFormatter& keyFormatter = DefaultKeyFormatter) const override;
+    /**
+     * @brief Render as markdown table
+     *
+     * @param keyFormatter GTSAM-style Key formatter.
+     * @param names optional, category names corresponding to choices.
+     * @return std::string a markdown string.
+     */
+    std::string markdown(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
+                         const Names& names = {}) const override;
 
     /// @}
 
diff --git a/gtsam/discrete/DiscreteBayesNet.cpp b/gtsam/discrete/DiscreteBayesNet.cpp
index d9fba630e5..510fb56389 100644
--- a/gtsam/discrete/DiscreteBayesNet.cpp
+++ b/gtsam/discrete/DiscreteBayesNet.cpp
@@ -63,12 +63,13 @@ namespace gtsam {
 
   /* ************************************************************************* */
   std::string DiscreteBayesNet::markdown(
-      const KeyFormatter& keyFormatter) const {
+      const KeyFormatter& keyFormatter,
+      const DiscreteFactor::Names& names) const {
     using std::endl;
     std::stringstream ss;
     ss << "`DiscreteBayesNet` of size " << size() << endl << endl;
     for(const DiscreteConditional::shared_ptr& conditional: *this)
-      ss << conditional->markdown(keyFormatter) << endl;
+      ss << conditional->markdown(keyFormatter, names) << endl;
     return ss.str();
   }
 /* ************************************************************************* */
diff --git a/gtsam/discrete/DiscreteBayesNet.h b/gtsam/discrete/DiscreteBayesNet.h
index aed4cec0aa..5332b51dd0 100644
--- a/gtsam/discrete/DiscreteBayesNet.h
+++ b/gtsam/discrete/DiscreteBayesNet.h
@@ -108,8 +108,8 @@ namespace gtsam {
     /// @{
 
     /// Render as markdown table.
-    std::string markdown(
-        const KeyFormatter& keyFormatter = DefaultKeyFormatter) const;
+    std::string markdown(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
+                         const DiscreteFactor::Names& names = {}) const;
 
     /// @}
 
diff --git a/gtsam/discrete/DiscreteBayesTree.cpp b/gtsam/discrete/DiscreteBayesTree.cpp
index 8a9186d05a..07d6e0f0ee 100644
--- a/gtsam/discrete/DiscreteBayesTree.cpp
+++ b/gtsam/discrete/DiscreteBayesTree.cpp
@@ -57,13 +57,14 @@ namespace gtsam {
 
   /* **************************************************************************/
   std::string DiscreteBayesTree::markdown(
-      const KeyFormatter& keyFormatter) const {
+      const KeyFormatter& keyFormatter,
+      const DiscreteFactor::Names& names) const {
     using std::endl;
     std::stringstream ss;
     ss << "`DiscreteBayesTree` of size " << nodes_.size() << endl << endl;
     auto visitor = [&](const DiscreteBayesTreeClique::shared_ptr& clique,
                        size_t& indent) {
-      ss << "\n" << clique->conditional()->markdown(keyFormatter);
+      ss << "\n" << clique->conditional()->markdown(keyFormatter, names);
       return indent + 1;
     };
     size_t indent;
diff --git a/gtsam/discrete/DiscreteBayesTree.h b/gtsam/discrete/DiscreteBayesTree.h
index 12d6017cc3..6189f25d54 100644
--- a/gtsam/discrete/DiscreteBayesTree.h
+++ b/gtsam/discrete/DiscreteBayesTree.h
@@ -93,8 +93,8 @@ class GTSAM_EXPORT DiscreteBayesTree
   /// @{
 
   /// Render as markdown table.
-  std::string markdown(
-      const KeyFormatter& keyFormatter = DefaultKeyFormatter) const;
+  std::string markdown(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
+                       const DiscreteFactor::Names& names = {}) const;
 
   /// @}
 };
diff --git a/gtsam/discrete/DiscreteConditional.cpp b/gtsam/discrete/DiscreteConditional.cpp
index 46d5509e06..b4f95780d5 100644
--- a/gtsam/discrete/DiscreteConditional.cpp
+++ b/gtsam/discrete/DiscreteConditional.cpp
@@ -282,9 +282,18 @@ size_t DiscreteConditional::sample(size_t parent_value) const {
   return sample(values);
 }
 
+/* ******************************************************************************** */
+size_t DiscreteConditional::sample() const {
+  if (nrParents() != 0)
+    throw std::invalid_argument(
+        "sample() can only be invoked on no-parent prior");
+  DiscreteValues values;
+  return sample(values);
+}
+
 /* ************************************************************************* */
-std::string DiscreteConditional::markdown(
-    const KeyFormatter& keyFormatter) const {
+std::string DiscreteConditional::markdown(const KeyFormatter& keyFormatter,
+                                          const Names& names) const {
   std::stringstream ss;
 
   // Print out signature.
@@ -317,7 +326,7 @@ std::string DiscreteConditional::markdown(
   ss << "|";
   const_iterator it;
   for(Key parent: parents()) {
-    ss << keyFormatter(parent) << "|";
+    ss << "*" << keyFormatter(parent) << "*|";
     pairs.emplace_back(parent, cardinalities_.at(parent));
   }
 
@@ -331,7 +340,10 @@ std::string DiscreteConditional::markdown(
                                                pairs.rend() - nrParents());
   const auto frontal_assignments = cartesianProduct(slatnorf);
   for (const auto& a : frontal_assignments) {
-    for (it = beginFrontals(); it != endFrontals(); ++it) ss << a.at(*it);
+    for (it = beginFrontals(); it != endFrontals(); ++it) {
+      size_t index = a.at(*it);
+      ss << Translate(names, *it, index);
+    }
     ss << "|";
   }
   ss << "\n";
@@ -348,8 +360,10 @@ std::string DiscreteConditional::markdown(
   for (const auto& a : assignments) {
     if (count == 0) {
       ss << "|";
-      for (it = beginParents(); it != endParents(); ++it)
-        ss << a.at(*it) << "|";
+      for (it = beginParents(); it != endParents(); ++it) {
+        size_t index = a.at(*it);
+        ss << Translate(names, *it, index) << "|";
+      }
     }
     ss << operator()(a) << "|";
     count = (count + 1) % n;
diff --git a/gtsam/discrete/DiscreteConditional.h b/gtsam/discrete/DiscreteConditional.h
index d21e3ae264..7ce3dc9308 100644
--- a/gtsam/discrete/DiscreteConditional.h
+++ b/gtsam/discrete/DiscreteConditional.h
@@ -162,9 +162,12 @@ class GTSAM_EXPORT DiscreteConditional: public DecisionTreeFactor,
   size_t sample(const DiscreteValues& parentsValues) const;
 
 
-  /// Single value version.
+  /// Single parent version.
   size_t sample(size_t parent_value) const;
 
+  /// Zero parent version.
+  size_t sample() const;
+
   /// @}
   /// @name Advanced Interface
   /// @{
@@ -180,8 +183,8 @@ class GTSAM_EXPORT DiscreteConditional: public DecisionTreeFactor,
   /// @{
 
   /// Render as markdown table.
-  std::string markdown(
-      const KeyFormatter& keyFormatter = DefaultKeyFormatter) const override;
+  std::string markdown(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
+                       const Names& names = {}) const override;
 
   /// @}
 };
diff --git a/gtsam/discrete/DiscreteFactor.cpp b/gtsam/discrete/DiscreteFactor.cpp
index c101653d28..1a12ef405a 100644
--- a/gtsam/discrete/DiscreteFactor.cpp
+++ b/gtsam/discrete/DiscreteFactor.cpp
@@ -19,9 +19,20 @@
 
 #include <gtsam/discrete/DiscreteFactor.h>
 
+#include <sstream>
+
 using namespace std;
 
 namespace gtsam {
 
-/* ************************************************************************* */
-} // namespace gtsam
+string DiscreteFactor::Translate(const Names& names, Key key, size_t index) {
+  if (names.empty()) {
+    stringstream ss;
+    ss << index;
+    return ss.str();
+  } else {
+    return names.at(key)[index];
+  }
+}
+
+}  // namespace gtsam
diff --git a/gtsam/discrete/DiscreteFactor.h b/gtsam/discrete/DiscreteFactor.h
index 76ed703bb2..e30c0a6fec 100644
--- a/gtsam/discrete/DiscreteFactor.h
+++ b/gtsam/discrete/DiscreteFactor.h
@@ -89,9 +89,22 @@ class GTSAM_EXPORT DiscreteFactor: public Factor {
   /// @name Wrapper support
   /// @{
   
-  /// Render as markdown table.
+  /// Translation table from values to strings.
+  using Names = std::map<Key, std::vector<std::string>>;
+
+  /// Translate an integer index value for given key to a string.
+  static std::string Translate(const Names& names, Key key, size_t index);
+
+  /**
+   * @brief Render as markdown table
+   * 
+   * @param keyFormatter GTSAM-style Key formatter.
+   * @param names optional, category names corresponding to choices.
+   * @return std::string a markdown string.
+   */
   virtual std::string markdown(
-      const KeyFormatter& keyFormatter = DefaultKeyFormatter) const = 0;
+      const KeyFormatter& keyFormatter = DefaultKeyFormatter,
+      const Names& names = {}) const = 0;
 
   /// @}
 };
diff --git a/gtsam/discrete/DiscreteFactorGraph.cpp b/gtsam/discrete/DiscreteFactorGraph.cpp
index bd84e13647..be046d2902 100644
--- a/gtsam/discrete/DiscreteFactorGraph.cpp
+++ b/gtsam/discrete/DiscreteFactorGraph.cpp
@@ -16,15 +16,17 @@
  *  @author Frank Dellaert
  */
 
-//#define ENABLE_TIMING
-#include <gtsam/discrete/DiscreteFactorGraph.h>
-#include <gtsam/discrete/DiscreteConditional.h>
 #include <gtsam/discrete/DiscreteBayesTree.h>
+#include <gtsam/discrete/DiscreteConditional.h>
 #include <gtsam/discrete/DiscreteEliminationTree.h>
+#include <gtsam/discrete/DiscreteFactorGraph.h>
 #include <gtsam/discrete/DiscreteJunctionTree.h>
-#include <gtsam/inference/FactorGraph-inst.h>
 #include <gtsam/inference/EliminateableFactorGraph-inst.h>
-#include <boost/make_shared.hpp>
+#include <gtsam/inference/FactorGraph-inst.h>
+
+using std::vector;
+using std::string;
+using std::map;
 
 namespace gtsam {
 
@@ -64,7 +66,7 @@ namespace gtsam {
   }
 
   /* ************************************************************************* */
-  void DiscreteFactorGraph::print(const std::string& s,
+  void DiscreteFactorGraph::print(const string& s,
       const KeyFormatter& formatter) const {
     std::cout << s << std::endl;
     std::cout << "size: " << size() << std::endl;
@@ -130,14 +132,15 @@ namespace gtsam {
   }
 
   /* ************************************************************************* */
-  std::string DiscreteFactorGraph::markdown(
-      const KeyFormatter& keyFormatter) const {
+  string DiscreteFactorGraph::markdown(
+      const KeyFormatter& keyFormatter,
+      const DiscreteFactor::Names& names) const {
     using std::endl;
     std::stringstream ss;
     ss << "`DiscreteFactorGraph` of size " << size() << endl << endl;
     for (size_t i = 0; i < factors_.size(); i++) {
       ss << "factor " << i << ":\n";
-      ss << factors_[i]->markdown(keyFormatter) << endl;
+      ss << factors_[i]->markdown(keyFormatter, names) << endl;
     }
     return ss.str();
   }
diff --git a/gtsam/discrete/DiscreteFactorGraph.h b/gtsam/discrete/DiscreteFactorGraph.h
index 6856493f7f..9aa04d6497 100644
--- a/gtsam/discrete/DiscreteFactorGraph.h
+++ b/gtsam/discrete/DiscreteFactorGraph.h
@@ -24,7 +24,10 @@
 #include <gtsam/discrete/DecisionTreeFactor.h>
 #include <gtsam/discrete/DiscreteBayesNet.h>
 #include <gtsam/base/FastSet.h>
+
 #include <boost/make_shared.hpp>
+#include <string>
+#include <vector>
 
 namespace gtsam {
 
@@ -140,9 +143,15 @@ public EliminateableFactorGraph<DiscreteFactorGraph> {
   /// @name Wrapper support
   /// @{
 
-  /// Render as markdown table.
-  std::string markdown(
-      const KeyFormatter& keyFormatter = DefaultKeyFormatter) const;
+  /**
+   * @brief Render as markdown table
+   * 
+   * @param keyFormatter GTSAM-style Key formatter.
+   * @param names optional, a map from Key to category names.
+   * @return std::string a (potentially long) markdown string.
+   */
+  std::string markdown(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
+                       const DiscreteFactor::Names& names = {}) const;
 
   /// @}
 }; // \ DiscreteFactorGraph
diff --git a/gtsam/discrete/DiscretePrior.h b/gtsam/discrete/DiscretePrior.h
index 1a7c6ae6cb..9ac8acb17a 100644
--- a/gtsam/discrete/DiscretePrior.h
+++ b/gtsam/discrete/DiscretePrior.h
@@ -98,7 +98,7 @@ class GTSAM_EXPORT DiscretePrior : public DiscreteConditional {
    * sample
    * @return sample from conditional
    */
-  size_t sample() const { return Base::sample({}); }
+  size_t sample() const { return Base::sample(); }
 
   /// @}
 };
diff --git a/gtsam/discrete/discrete.i b/gtsam/discrete/discrete.i
index 5bd4a2913a..a837328838 100644
--- a/gtsam/discrete/discrete.i
+++ b/gtsam/discrete/discrete.i
@@ -52,6 +52,8 @@ virtual class DecisionTreeFactor : gtsam::DiscreteFactor {
   std::vector<std::pair<DiscreteValues, double>> enumerate() const;
   string markdown(const gtsam::KeyFormatter& keyFormatter =
                       gtsam::DefaultKeyFormatter) const;
+  string markdown(const gtsam::KeyFormatter& keyFormatter,
+                  std::map<gtsam::Key, std::vector<std::string>> names) const;
 };
 
 #include <gtsam/discrete/DiscreteConditional.h>
@@ -84,10 +86,13 @@ virtual class DiscreteConditional : gtsam::DecisionTreeFactor {
   size_t solve(const gtsam::DiscreteValues& parentsValues) const;
   size_t sample(const gtsam::DiscreteValues& parentsValues) const;
   size_t sample(size_t value) const;
+  size_t sample() const;
   void solveInPlace(gtsam::DiscreteValues @parentsValues) const;
   void sampleInPlace(gtsam::DiscreteValues @parentsValues) const;
   string markdown(const gtsam::KeyFormatter& keyFormatter =
                       gtsam::DefaultKeyFormatter) const;
+  string markdown(const gtsam::KeyFormatter& keyFormatter,
+                  std::map<gtsam::Key, std::vector<std::string>> names) const;
 };
 
 #include <gtsam/discrete/DiscretePrior.h>
@@ -101,7 +106,6 @@ virtual class DiscretePrior : gtsam::DiscreteConditional {
   double operator()(size_t value) const;
   std::vector<double> pmf() const;
   size_t solve() const;
-  size_t sample() const;
 };
 
 #include <gtsam/discrete/DiscreteBayesNet.h>
@@ -130,6 +134,8 @@ class DiscreteBayesNet {
   gtsam::DiscreteValues sample() const;
   string markdown(const gtsam::KeyFormatter& keyFormatter =
                       gtsam::DefaultKeyFormatter) const;
+  string markdown(const gtsam::KeyFormatter& keyFormatter,
+                  std::map<gtsam::Key, std::vector<std::string>> names) const;
 };
 
 #include <gtsam/discrete/DiscreteBayesTree.h>
@@ -164,6 +170,8 @@ class DiscreteBayesTree {
 
   string markdown(const gtsam::KeyFormatter& keyFormatter =
                  gtsam::DefaultKeyFormatter) const;
+  string markdown(const gtsam::KeyFormatter& keyFormatter,
+                  std::map<gtsam::Key, std::vector<std::string>> names) const;
 };
 
 #include <gtsam/inference/DotWriter.h>
@@ -211,6 +219,8 @@ class DiscreteFactorGraph {
 
   string markdown(const gtsam::KeyFormatter& keyFormatter =
                  gtsam::DefaultKeyFormatter) const;
+  string markdown(const gtsam::KeyFormatter& keyFormatter,
+                  std::map<gtsam::Key, std::vector<std::string>> names) const;
 };
 
 }  // namespace gtsam
diff --git a/gtsam/discrete/tests/testDecisionTreeFactor.cpp b/gtsam/discrete/tests/testDecisionTreeFactor.cpp
index 6af7ca7313..c4e5f06bb3 100644
--- a/gtsam/discrete/tests/testDecisionTreeFactor.cpp
+++ b/gtsam/discrete/tests/testDecisionTreeFactor.cpp
@@ -119,6 +119,27 @@ TEST(DecisionTreeFactor, markdown) {
   EXPECT(actual == expected);
 }
 
+/* ************************************************************************* */
+// Check markdown representation with a value formatter.
+TEST(DecisionTreeFactor, markdownWithValueFormatter) {
+  DiscreteKey A(12, 3), B(5, 2);
+  DecisionTreeFactor f(A & B, "1 2  3 4  5 6");
+  string expected =
+      "|A|B|value|\n"
+      "|:-:|:-:|:-:|\n"
+      "|Zero|-|1|\n"
+      "|Zero|+|2|\n"
+      "|One|-|3|\n"
+      "|One|+|4|\n"
+      "|Two|-|5|\n"
+      "|Two|+|6|\n";
+  auto keyFormatter = [](Key key) { return key == 12 ? "A" : "B"; };
+  DecisionTreeFactor::Names names{{12, {"Zero", "One", "Two"}},
+                                  {5, {"-", "+"}}};
+  string actual = f.markdown(keyFormatter, names);
+  EXPECT(actual == expected);
+}
+
 /* ************************************************************************* */
 int main() {
   TestResult tr;
diff --git a/gtsam/discrete/tests/testDiscreteBayesNet.cpp b/gtsam/discrete/tests/testDiscreteBayesNet.cpp
index 1de45905a6..251978c99b 100644
--- a/gtsam/discrete/tests/testDiscreteBayesNet.cpp
+++ b/gtsam/discrete/tests/testDiscreteBayesNet.cpp
@@ -187,7 +187,7 @@ TEST(DiscreteBayesNet, markdown) {
       "|1|0.01|\n"
       "\n"
       " *P(Smoking|Asia)*:\n\n"
-      "|Asia|0|1|\n"
+      "|*Asia*|0|1|\n"
       "|:-:|:-:|:-:|\n"
       "|0|0.8|0.2|\n"
       "|1|0.7|0.3|\n\n";
diff --git a/gtsam/discrete/tests/testDiscreteConditional.cpp b/gtsam/discrete/tests/testDiscreteConditional.cpp
index 00ae1acd01..b498b0541a 100644
--- a/gtsam/discrete/tests/testDiscreteConditional.cpp
+++ b/gtsam/discrete/tests/testDiscreteConditional.cpp
@@ -143,7 +143,7 @@ TEST(DiscreteConditional, markdown_multivalued) {
       A | B = "2/88/10 2/20/78 33/33/34 33/33/34 95/2/3");
   string expected =
       " *P(a1|b1)*:\n\n"
-      "|b1|0|1|2|\n"
+      "|*b1*|0|1|2|\n"
       "|:-:|:-:|:-:|:-:|\n"
       "|0|0.02|0.88|0.1|\n"
       "|1|0.02|0.2|0.78|\n"
@@ -161,17 +161,19 @@ TEST(DiscreteConditional, markdown) {
   DiscreteConditional conditional(A, {B, C}, "0/1 1/3  1/1 3/1  0/1 1/0");
   string expected =
       " *P(A|B,C)*:\n\n"
-      "|B|C|0|1|\n"
+      "|*B*|*C*|T|F|\n"
       "|:-:|:-:|:-:|:-:|\n"
-      "|0|0|0|1|\n"
-      "|0|1|0.25|0.75|\n"
-      "|0|2|0.5|0.5|\n"
-      "|1|0|0.75|0.25|\n"
-      "|1|1|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.markdown(formatter);
+      "|-|Zero|0|1|\n"
+      "|-|One|0.25|0.75|\n"
+      "|-|Two|0.5|0.5|\n"
+      "|+|Zero|0.75|0.25|\n"
+      "|+|One|0|1|\n"
+      "|+|Two|1|0|\n";
+  vector<string> keyNames{"C", "B", "A"};
+  auto formatter = [keyNames](Key key) { return keyNames[key]; };
+  DecisionTreeFactor::Names names{
+      {0, {"Zero", "One", "Two"}}, {1, {"-", "+"}}, {2, {"T", "F"}}};
+  string actual = conditional.markdown(formatter, names);
   EXPECT(actual == expected);
 }
 
diff --git a/gtsam/discrete/tests/testDiscretePrior.cpp b/gtsam/discrete/tests/testDiscretePrior.cpp
index b91926cc05..23f093b229 100644
--- a/gtsam/discrete/tests/testDiscretePrior.cpp
+++ b/gtsam/discrete/tests/testDiscretePrior.cpp
@@ -28,6 +28,8 @@ static const DiscreteKey X(0, 2);
 /* ************************************************************************* */
 TEST(DiscretePrior, constructors) {
   DiscretePrior actual(X % "2/3");
+  EXPECT_LONGS_EQUAL(1, actual.nrFrontals());
+  EXPECT_LONGS_EQUAL(0, actual.nrParents());
   DecisionTreeFactor f(X, "0.4 0.6");
   DiscretePrior expected(f);
   EXPECT(assert_equal(expected, actual, 1e-9));
@@ -41,12 +43,18 @@ TEST(DiscretePrior, operator) {
 }
 
 /* ************************************************************************* */
-TEST(DiscretePrior, to_vector) {
+TEST(DiscretePrior, pmf) {
   DiscretePrior prior(X % "2/3");
   vector<double> expected {0.4, 0.6};
   EXPECT(prior.pmf() ==  expected);
 }
 
+/* ************************************************************************* */
+TEST(DiscretePrior, sample) {
+  DiscretePrior prior(X % "2/3");
+  prior.sample();
+}
+
 /* ************************************************************************* */
 int main() {
   TestResult tr;
diff --git a/gtsam_unstable/discrete/Constraint.h b/gtsam_unstable/discrete/Constraint.h
index 5c21028a0c..85748f0546 100644
--- a/gtsam_unstable/discrete/Constraint.h
+++ b/gtsam_unstable/discrete/Constraint.h
@@ -86,8 +86,8 @@ class GTSAM_EXPORT Constraint : public DiscreteFactor {
   /// @{
 
   /// Render as markdown table.
-  std::string markdown(
-      const KeyFormatter& keyFormatter = DefaultKeyFormatter) const override {
+  std::string markdown(const KeyFormatter& keyFormatter = DefaultKeyFormatter,
+                       const Names& names = {}) const override {
     return (boost::format("`Constraint` on %1% variables\n") % (size())).str();
   }
 
diff --git a/gtsam_unstable/discrete/examples/schedulingExample.cpp b/gtsam_unstable/discrete/examples/schedulingExample.cpp
index 3460664db7..2a9addf918 100644
--- a/gtsam_unstable/discrete/examples/schedulingExample.cpp
+++ b/gtsam_unstable/discrete/examples/schedulingExample.cpp
@@ -115,7 +115,7 @@ void runLargeExample() {
   // Do brute force product and output that to file
   if (scheduler.nrStudents() == 1) { // otherwise too slow
     DecisionTreeFactor product = scheduler.product();
-    product.dot("scheduling-large", false);
+    product.dot("scheduling-large", DefaultKeyFormatter, false);
   }
 
   // Do exact inference
diff --git a/gtsam_unstable/discrete/examples/schedulingQuals12.cpp b/gtsam_unstable/discrete/examples/schedulingQuals12.cpp
index 19694c31ec..8260bfb068 100644
--- a/gtsam_unstable/discrete/examples/schedulingQuals12.cpp
+++ b/gtsam_unstable/discrete/examples/schedulingQuals12.cpp
@@ -115,7 +115,7 @@ void runLargeExample() {
   // Do brute force product and output that to file
   if (scheduler.nrStudents() == 1) { // otherwise too slow
     DecisionTreeFactor product = scheduler.product();
-    product.dot("scheduling-large", false);
+    product.dot("scheduling-large", DefaultKeyFormatter, false);
   }
 
   // Do exact inference
diff --git a/gtsam_unstable/discrete/examples/schedulingQuals13.cpp b/gtsam_unstable/discrete/examples/schedulingQuals13.cpp
index 4b96b1eeba..cf3ce04535 100644
--- a/gtsam_unstable/discrete/examples/schedulingQuals13.cpp
+++ b/gtsam_unstable/discrete/examples/schedulingQuals13.cpp
@@ -139,7 +139,7 @@ void runLargeExample() {
   // Do brute force product and output that to file
   if (scheduler.nrStudents() == 1) { // otherwise too slow
     DecisionTreeFactor product = scheduler.product();
-    product.dot("scheduling-large", false);
+    product.dot("scheduling-large", DefaultKeyFormatter, false);
   }
 
   // Do exact inference
diff --git a/python/gtsam/tests/test_DiscreteConditional.py b/python/gtsam/tests/test_DiscreteConditional.py
index 1b2ce70cd7..86bc303a9a 100644
--- a/python/gtsam/tests/test_DiscreteConditional.py
+++ b/python/gtsam/tests/test_DiscreteConditional.py
@@ -50,7 +50,7 @@ def test_markdown(self):
                                           "0/1 1/3  1/1 3/1  0/1 1/0")
         expected = \
             " *P(A|B,C)*:\n\n" \
-            "|B|C|0|1|\n" \
+            "|*B*|*C*|0|1|\n" \
             "|:-:|:-:|:-:|:-:|\n" \
             "|0|0|0|1|\n" \
             "|0|1|0.25|0.75|\n" \
diff --git a/python/gtsam/tests/test_DiscretePrior.py b/python/gtsam/tests/test_DiscretePrior.py
index 4f017d66a4..5bf6a8d196 100644
--- a/python/gtsam/tests/test_DiscretePrior.py
+++ b/python/gtsam/tests/test_DiscretePrior.py
@@ -6,7 +6,7 @@
 See LICENSE for the license information
 
 Unit tests for Discrete Priors.
-Author: Varun Agrawal
+Author: Frank Dellaert
 """
 
 # pylint: disable=no-name-in-module, invalid-name
@@ -42,6 +42,11 @@ def test_pmf(self):
         expected = np.array([0.4, 0.6])
         np.testing.assert_allclose(expected, prior.pmf())
 
+    def test_sample(self):
+        prior = DiscretePrior(X, "2/3")
+        actual = prior.sample()
+        self.assertIsInstance(actual, int)
+
     def test_markdown(self):
         """Test the _repr_markdown_ method."""