default rng argument to make code DRY

gtsam/discrete/DiscreteBayesNet.cpp

@@ -50,12 +50,13 @@ double DiscreteBayesNet::evaluate(const DiscreteValues& values) const {
 }
 
 /* ************************************************************************* */
-DiscreteValues DiscreteBayesNet::sample() const {
+DiscreteValues DiscreteBayesNet::sample(std::mt19937_64* rng) const {
   DiscreteValues result;
   return sample(result);
 }
 
-DiscreteValues DiscreteBayesNet::sample(DiscreteValues result) const {
+DiscreteValues DiscreteBayesNet::sample(DiscreteValues result,
+                                        std::mt19937_64* rng) const {
   // sample each node in turn in topological sort order (parents first)
   for (auto it = std::make_reverse_iterator(end());
        it != std::make_reverse_iterator(begin()); ++it) {
@@ -63,7 +64,7 @@ DiscreteValues DiscreteBayesNet::sample(DiscreteValues result) const {
     // Sample the conditional only if value for j not already in result
     const Key j = conditional->firstFrontalKey();
     if (result.count(j) == 0) {
-      conditional->sampleInPlace(&result);
+      conditional->sampleInPlace(&result, rng);
     }
   }
   return result;

gtsam/discrete/DiscreteBayesNet.h

@@ -112,7 +112,7 @@ class GTSAM_EXPORT DiscreteBayesNet: public BayesNet<DiscreteConditional> {
      *
      * @return a sampled value for all variables.
      */
-    DiscreteValues sample() const;
+    DiscreteValues sample(std::mt19937_64* rng = &kRandomNumberGenerator) const;
 
     /**
      * @brief do ancestral sampling, given certain variables.
@@ -122,7 +122,8 @@ class GTSAM_EXPORT DiscreteBayesNet: public BayesNet<DiscreteConditional> {
      *
      * @return given values extended with sampled value for all other variables.
      */
-    DiscreteValues sample(DiscreteValues given) const;
+    DiscreteValues sample(DiscreteValues given,
+                          std::mt19937_64* rng = &kRandomNumberGenerator) const;
 
     /**
      * @brief Prune the Bayes net

gtsam/discrete/DiscreteConditional.cpp

@@ -32,9 +32,6 @@
 #include <utility>
 #include <vector>
 
-// In wrappers we can access std::mt19937_64 via gtsam.MT19937
-static std::mt19937_64 kRandomNumberGenerator(2);
-
 using namespace std;
 using std::pair;
 using std::stringstream;
@@ -271,7 +268,8 @@ size_t DiscreteConditional::argmax(const DiscreteValues& parentsValues) const {
 }
 
 /* ************************************************************************** */
-void DiscreteConditional::sampleInPlace(DiscreteValues* values) const {
+void DiscreteConditional::sampleInPlace(DiscreteValues* values,
+                                        std::mt19937_64* rng) const {
   // throw if more than one frontal:
   if (nrFrontals() != 1) {
     throw std::invalid_argument(
@@ -284,13 +282,8 @@ void DiscreteConditional::sampleInPlace(DiscreteValues* values) const {
     throw std::invalid_argument(
         "DiscreteConditional::sampleInPlace: values already contains j");
   }
-  size_t sampled = sample(*values);  // Sample variable given parents
+  size_t sampled = sample(*values, rng);  // Sample variable given parents
-  (*values)[j] = sampled;            // store result in partial solution
+  (*values)[j] = sampled;                 // store result in partial solution
-}
-
-/* ************************************************************************** */
-size_t DiscreteConditional::sample(const DiscreteValues& parentsValues) const {
-  return sample(parentsValues, &kRandomNumberGenerator);
 }
 
 /* ************************************************************************** */
@@ -320,11 +313,6 @@ size_t DiscreteConditional::sample(const DiscreteValues& parentsValues,
   return distribution(*rng);
 }
 
-/* ************************************************************************** */
-size_t DiscreteConditional::sample(size_t parent_value) const {
-  return sample(parent_value, &kRandomNumberGenerator);
-}
-
 /* ************************************************************************** */
 size_t DiscreteConditional::sample(size_t parent_value,
                                    std::mt19937_64* rng) const {
@@ -337,11 +325,6 @@ size_t DiscreteConditional::sample(size_t parent_value,
   return sample(values, rng);
 }
 
-/* ************************************************************************** */
-size_t DiscreteConditional::sample() const {
-  return sample(&kRandomNumberGenerator);
-}
-
 /* ************************************************************************** */
 size_t DiscreteConditional::sample(std::mt19937_64* rng) const {
   if (nrParents() != 0)

gtsam/discrete/DiscreteConditional.h

@@ -27,6 +27,9 @@
 #include <string>
 #include <vector>
 
+// In wrappers we can access std::mt19937_64 via gtsam.MT19937
+static std::mt19937_64 kRandomNumberGenerator(42);
+
 namespace gtsam {
 
 /**
@@ -195,31 +198,23 @@ class GTSAM_EXPORT DiscreteConditional
   /** Single variable version of likelihood. */
   DecisionTreeFactor::shared_ptr likelihood(size_t frontal) const;
 
-  /**
-   * sample
-   * @param parentsValues Known values of the parents
-   * @return sample from conditional
-   */
-  virtual size_t sample(const DiscreteValues& parentsValues) const;
-
   /**
    * Sample from conditional, given missing variables
    * Example:
    *   std::mt19937_64 rng(42);
    *   DiscreteValues given = ...;
    *   size_t sample = dc.sample(given, &rng);
+   *
+   * @param parentsValues Known values of the parents
+   * @param rng Pseudo-Random Number Generator.
+   * @return sample from conditional
    */
-  size_t sample(const DiscreteValues& parentsValues,
+  virtual size_t sample(const DiscreteValues& parentsValues,
-                std::mt19937_64* rng) const;
+                        std::mt19937_64* rng = &kRandomNumberGenerator) const;
 
   /// Single parent version.
-  size_t sample(size_t parent_value) const;
+  size_t sample(size_t parent_value,
-
+                std::mt19937_64* rng = &kRandomNumberGenerator) const;
-  /// Single parent version with PRNG
-  size_t sample(size_t parent_value, std::mt19937_64* rng) const;
-
-  /// Zero parent version.
-  size_t sample() const;
 
   /**
    * Sample from conditional, zero parent version
@@ -227,7 +222,7 @@ class GTSAM_EXPORT DiscreteConditional
    *   std::mt19937_64 rng(42);
    *   auto sample = dc.sample(&rng);
    */
-  size_t sample(std::mt19937_64* rng) const;
+  size_t sample(std::mt19937_64* rng = &kRandomNumberGenerator) const;
 
   /**
    * @brief Return assignment for single frontal variable that maximizes value.
@@ -249,8 +244,9 @@ class GTSAM_EXPORT DiscreteConditional
   /// @name Advanced Interface
   /// @{
 
-  /// sample in place, stores result in partial solution
+  /// Sample in place with optional PRNG, stores result in partial solution
-  void sampleInPlace(DiscreteValues* parentsValues) const;
+  void sampleInPlace(DiscreteValues* parentsValues,
+                     std::mt19937_64* rng = &kRandomNumberGenerator) const;
 
   /// Return all assignments for frontal variables.
   std::vector<DiscreteValues> frontalAssignments() const;

gtsam/discrete/TableDistribution.cpp

@@ -144,9 +144,8 @@ void TableDistribution::prune(size_t maxNrAssignments) {
 }
 
 /* ****************************************************************************/
-size_t TableDistribution::sample(const DiscreteValues& parentsValues) const {
+size_t TableDistribution::sample(const DiscreteValues& parentsValues,
-  static mt19937 rng(2);  // random number generator
+                                 std::mt19937_64* rng) const {
-
   DiscreteKeys parentsKeys;
   for (auto&& [key, _] : parentsValues) {
     parentsKeys.push_back({key, table_.cardinality(key)});
@@ -173,7 +172,7 @@ size_t TableDistribution::sample(const DiscreteValues& parentsValues) const {
     }
   }
   std::discrete_distribution<size_t> distribution(p.begin(), p.end());
-  return distribution(rng);
+  return distribution(*rng);
 }
 
 }  // namespace gtsam

gtsam/discrete/TableDistribution.h

@@ -143,9 +143,12 @@ class GTSAM_EXPORT TableDistribution : public DiscreteConditional {
   /**
    * sample
    * @param parentsValues Known values of the parents
+   * @param rng Pseudo random number generator
    * @return sample from conditional
    */
-  virtual size_t sample(const DiscreteValues& parentsValues) const override;
+  virtual size_t sample(
+      const DiscreteValues& parentsValues,
+      std::mt19937_64* rng = &kRandomNumberGenerator) const override;
 
   /// @}
   /// @name Advanced Interface