Draft implementation of SetChanceProbs that requires chance moves to …

…have sum-to-one probs.
gambitproject · Sep 7, 2023 · 18d8df6 · 18d8df6
1 parent 8e6bca0
commit 18d8df6
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diff --git a/src/games/game.h b/src/games/game.h
@@ -881,6 +881,12 @@ class GameRep : public BaseGameRep {
   /// Returns the number of nodes in the game
   virtual int NumNodes() const = 0;
   //@}
+
+  /// @name Modification
+  //@{
+  /// Set the probability distribution of actions at a chance node
+  virtual Game SetChanceProbs(const GameInfoset &, const Array<Number> &) = 0;
+  //@}
 };
 
 typedef GameObjectPtr<GameRep> Game;

diff --git a/src/games/gameagg.h b/src/games/gameagg.h
@@ -144,6 +144,11 @@ class GameAggRep : public GameRep {
 
   //@}
 
+  /// @name Modification
+  //@{
+  Game SetChanceProbs(const GameInfoset &, const Array<Number> &) override { throw UndefinedException(); }
+  //@}
+
   /// @name Writing data files
   //@{
   /// Write the game to a savefile in the specified format.

diff --git a/src/games/gamebagg.h b/src/games/gamebagg.h
@@ -150,6 +150,11 @@ class GameBagentRep : public GameRep {
   { throw UndefinedException(); }
   virtual void WriteBaggFile(std::ostream &) const;  
   //@}
+
+  /// @name Modification
+  //@{
+  Game SetChanceProbs(const GameInfoset &, const Array<Number> &) override { throw UndefinedException(); }
+  //@}
 };
 
 } // end namespace Gambit

diff --git a/src/games/gametable.h b/src/games/gametable.h
@@ -120,6 +120,10 @@ class GameTableRep : public GameExplicitRep {
   //@{
   /// Write the game to a file in .nfg outcome format
   void WriteNfgFile(std::ostream &) const override;
+
+  /// @name Modification
+  //@{
+  Game SetChanceProbs(const GameInfoset &, const Array<Number> &) override { throw UndefinedException(); }
   //@}
 
   PureStrategyProfile NewPureStrategyProfile() const override;

diff --git a/src/games/gametree.cc b/src/games/gametree.cc
@@ -21,6 +21,7 @@
 //
 
 #include <iostream>
+#include <numeric>
 
 #include "gambit.h"
 #include "gametree.h"
@@ -1026,6 +1027,34 @@ int GameTreeRep::NumNodes() const
   return CountNodes(m_root);
 }
 
+
+//------------------------------------------------------------------------
+//                       GameTreeRep: Modification
+//------------------------------------------------------------------------
+
+Game GameTreeRep::SetChanceProbs(const GameInfoset &p_infoset, const Array<Number> &p_probs)
+{
+  if (!p_infoset->IsChanceInfoset()) {
+    throw UndefinedException();
+  }
+  if (p_infoset->NumActions() != p_probs.size()) {
+    throw DimensionException();
+  }
+  Rational sum(0);
+  for (auto prob : p_probs) {
+    sum += static_cast<Rational>(prob);
+  }
+  if (sum != Rational(1)) {
+    throw ValueException();
+  }
+  for (int act = 1; act <= p_infoset->NumActions(); act++) {
+    dynamic_cast<GameTreeInfosetRep &>(*p_infoset).m_probs[act] = p_probs[act];
+  }
+  ClearComputedValues();
+  return this;
+}
+
+
 //------------------------------------------------------------------------
 //                     GameTreeRep: Factory functions
 //------------------------------------------------------------------------

diff --git a/src/games/gametree.h b/src/games/gametree.h
@@ -279,6 +279,11 @@ class GameTreeRep : public GameExplicitRep {
   GameAction GetAction(int act) const override;
   //@}
 
+  /// @name Modification
+  //@{
+  Game SetChanceProbs(const GameInfoset &, const Array<Number> &) override;
+  //@}
+
   PureStrategyProfile NewPureStrategyProfile() const override;
   MixedStrategyProfile<double> NewMixedStrategyProfile(double) const override;
   MixedStrategyProfile<Rational> NewMixedStrategyProfile(const Rational &) const override;