Modernisation and consistency of regret and liap values (#672)

* For mixed strategy profiles, be consistent in using the cached payoffs for both liap value and regret
* Refactor some common code (e.g. maximising a function over a container of values) into a suitable template
* Make mixed behaviour profiles parallel with mixed strategy profiles in the implementation style of liap value and regret.

Author: tturocy

src/core/util.h

@@ -28,6 +28,7 @@
 #include <iomanip>
 #include <cmath>
 #include <algorithm>
+#include <numeric>
 #include <map>
 
 namespace Gambit {
@@ -63,6 +64,99 @@ template <class Key, class T> bool contains(const std::map<Key, T> &map, const K
 {
   return map.find(key) != map.end();
 }
+
+/// @brief A container adaptor which skips over a given value when iterating
+template <typename Container, typename T> class exclude_value {
+public:
+  using Iter = decltype(std::begin(std::declval<Container &>()));
+
+  class iterator {
+  public:
+    using iterator_category = std::forward_iterator_tag;
+    using value_type = typename std::iterator_traits<Iter>::value_type;
+    using difference_type = typename std::iterator_traits<Iter>::difference_type;
+    using reference = typename std::iterator_traits<Iter>::reference;
+    using pointer = typename std::iterator_traits<Iter>::pointer;
+
+    iterator(Iter current, Iter end, const T &value)
+      : m_current(current), m_end(end), m_value(value)
+    {
+      skip_if_value();
+    }
+
+    value_type operator*() const { return *m_current; }
+    pointer operator->() const { return std::addressof(*m_current); }
+
+    iterator &operator++()
+    {
+      ++m_current;
+      skip_if_value();
+      return *this;
+    }
+
+    iterator operator++(int)
+    {
+      auto tmp = *this;
+      ++(*this);
+      return tmp;
+    }
+
+    friend bool operator==(const iterator &a, const iterator &b)
+    {
+      return a.m_current == b.m_current;
+    }
+
+    friend bool operator!=(const iterator &a, const iterator &b)
+    {
+      return a.m_current != b.m_current;
+    }
+
+  private:
+    Iter m_current, m_end;
+    T m_value;
+
+    void skip_if_value()
+    {
+      while (m_current != m_end && *m_current == m_value) {
+        ++m_current;
+      }
+    }
+  };
+
+  exclude_value(const Container &c, const T &value)
+    : m_begin(c.begin(), c.end(), value), m_end(c.end(), c.end(), value)
+  {
+  }
+
+  iterator begin() const { return m_begin; }
+  iterator end() const { return m_end; }
+
+private:
+  iterator m_begin, m_end;
+};
+
+/// @brief Returns the maximum value of the function over the *non-empty* container
+template <class Container, class Func>
+auto maximize_function(const Container &p_container, const Func &p_function)
+{
+  auto it = p_container.begin();
+  using T = decltype(p_function(*it));
+  return std::transform_reduce(
+      std::next(it), p_container.end(), p_function(*it),
+      [](const T &a, const T &b) -> T { return std::max(a, b); }, p_function);
+}
+
+/// @brief Returns the minimum value of the function over the *non-empty* container
+template <class Container, class Func>
+auto minimize_function(const Container &p_container, const Func &p_function)
+{
+  auto it = p_container.begin();
+  using T = decltype(p_function(*it));
+  return std::transform_reduce(
+      std::next(it), p_container.end(), p_function(*it),
+      [](const T &a, const T &b) -> T { return std::min(a, b); }, p_function);
+}
+
 //========================================================================
 //                        Exception classes
 //========================================================================

src/games/behavmixed.cc

@@ -266,12 +266,11 @@ template <class T> T MixedBehaviorProfile<T>::GetLiapValue() const
   CheckVersion();
   ComputeSolutionData();
 
-  auto value = T(0);
-  for (auto player : m_support.GetGame()->GetPlayers()) {
-    for (auto infoset : player->GetInfosets()) {
-      for (auto action : m_support.GetActions(infoset)) {
-        value += sqr(std::max(GetPayoff(action) - GetPayoff(infoset), T(0)));
-      }
+  auto value = static_cast<T>(0);
+  for (auto infoset : m_support.GetGame()->GetInfosets()) {
+    for (auto action : m_support.GetActions(infoset)) {
+      value +=
+          sqr(std::max(map_actionValues[action] - map_infosetValues[infoset], static_cast<T>(0)));
     }
   }
   return value;
@@ -352,24 +351,23 @@ template <class T> const T &MixedBehaviorProfile<T>::GetRegret(const GameAction
 {
   CheckVersion();
   ComputeSolutionData();
-  return map_regret[act];
+  return map_regret.at(act);
 }
 
 template <class T> T MixedBehaviorProfile<T>::GetRegret(const GameInfoset &p_infoset) const
 {
-  auto actions = p_infoset->GetActions();
-  T br_payoff = std::accumulate(
-      std::next(actions.begin()), actions.end(), GetPayoff(*actions.begin()),
-      [this](const T &x, const GameAction &action) { return std::max(x, GetPayoff(action)); });
-  return br_payoff - GetPayoff(p_infoset);
+  CheckVersion();
+  ComputeSolutionData();
+  T br_payoff = maximize_function(p_infoset->GetActions(), [this](const auto &action) -> T {
+    return map_actionValues.at(action);
+  });
+  return br_payoff - map_infosetValues[p_infoset];
 }
 
 template <class T> T MixedBehaviorProfile<T>::GetMaxRegret() const
 {
-  auto infosets = m_support.GetGame()->GetInfosets();
-  return std::accumulate(
-      infosets.begin(), infosets.end(), T(0),
-      [this](const T &x, const GameInfoset &infoset) { return std::max(x, GetRegret(infoset)); });
+  return maximize_function(m_support.GetGame()->GetInfosets(),
+                           [this](const auto &infoset) -> T { return this->GetRegret(infoset); });
 }
 
 template <class T>

src/games/file.cc

@@ -20,14 +20,13 @@
 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 //
 
-#include <cstdlib>
-#include <cctype>
 #include <iostream>
 #include <fstream>
 #include <map>
 #include <algorithm>
 
 #include "gambit.h"
+#include "gameagg.h"
 
 namespace {
 // This anonymous namespace encapsulates the file-parsing code

src/games/game.cc

@@ -251,7 +251,7 @@ MixedStrategyProfileRep<T>::MixedStrategyProfileRep(const StrategySupportProfile
 template <class T> void MixedStrategyProfileRep<T>::SetCentroid()
 {
   for (auto player : m_support.GetGame()->GetPlayers()) {
-    T center = T(1) / T(m_support.GetStrategies(player).size());
+    T center = static_cast<T>(1) / static_cast<T>(m_support.GetStrategies(player).size());
     for (auto strategy : m_support.GetStrategies(player)) {
       (*this)[strategy] = center;
     }
@@ -277,39 +277,6 @@ std::unique_ptr<MixedStrategyProfileRep<T>> MixedStrategyProfileRep<T>::Normaliz
   return norm;
 }
 
-template <class T> T MixedStrategyProfileRep<T>::GetRegret(const GameStrategy &p_strategy) const
-{
-  const GamePlayer player = p_strategy->GetPlayer();
-  T payoff = GetPayoffDeriv(player->GetNumber(), p_strategy);
-  T brpayoff = payoff;
-  for (auto strategy : player->GetStrategies()) {
-    if (strategy != p_strategy) {
-      brpayoff = std::max(brpayoff, GetPayoffDeriv(player->GetNumber(), strategy));
-    }
-  }
-  return brpayoff - payoff;
-}
-
-template <class T> T MixedStrategyProfileRep<T>::GetRegret(const GamePlayer &p_player) const
-{
-  auto strategies = p_player->GetStrategies();
-  T br_payoff = std::accumulate(std::next(strategies.begin()), strategies.end(),
-                                GetPayoff(*strategies.begin()),
-                                [this](const T &x, const GameStrategy &strategy) {
-                                  return std::max(x, GetPayoff(strategy));
-                                });
-  return br_payoff - GetPayoff(p_player);
-}
-
-template <class T> T MixedStrategyProfileRep<T>::GetMaxRegret() const
-{
-  auto players = m_support.GetGame()->GetPlayers();
-  return std::accumulate(players.begin(), players.end(), T(0),
-                         [this](const T &x, const GamePlayer &player) {
-                           return std::max(x, this->GetRegret(player));
-                         });
-}
-
 //========================================================================
 //                 MixedStrategyProfile<T>: Lifecycle
 //========================================================================
@@ -333,8 +300,7 @@ MixedStrategyProfile<T>::MixedStrategyProfile(const MixedBehaviorProfile<T> &p_p
 }
 
 template <class T>
-MixedStrategyProfile<T> &
-MixedStrategyProfile<T>::operator=(const MixedStrategyProfile<T> &p_profile)
+MixedStrategyProfile<T> &MixedStrategyProfile<T>::operator=(const MixedStrategyProfile &p_profile)
 {
   if (this != &p_profile) {
     InvalidateCache();
@@ -377,16 +343,15 @@ template <class T> MixedStrategyProfile<T> MixedStrategyProfile<T>::ToFullSuppor
 
 template <class T> void MixedStrategyProfile<T>::ComputePayoffs() const
 {
-  if (!map_profile_payoffs.empty()) {
-    // caches (map_profile_payoffs and map_strategy_payoffs) are valid,
+  if (!m_payoffs.empty()) {
+    // caches (m_payoffs and m_strategyValues) are valid,
     // so don't compute anything, simply return
     return;
   }
   for (const auto &player : m_rep->m_support.GetPlayers()) {
-    map_profile_payoffs[player] = GetPayoff(player);
-    // values of the player's strategies
+    m_payoffs[player] = GetPayoff(player);
     for (const auto &strategy : m_rep->m_support.GetStrategies(player)) {
-      map_strategy_payoffs[player][strategy] = GetPayoff(strategy);
+      m_strategyValues[player][strategy] = GetPayoff(strategy);
     }
   }
 };
@@ -397,14 +362,47 @@ template <class T> T MixedStrategyProfile<T>::GetLiapValue() const
   ComputePayoffs();
 
   auto liapValue = static_cast<T>(0);
-  for (auto [player, payoff] : map_profile_payoffs) {
-    for (auto v : map_strategy_payoffs[player]) {
-      liapValue += sqr(std::max(v.second - payoff, static_cast<T>(0)));
-    }
+  for (auto p : m_payoffs) {
+    liapValue += std::transform_reduce(
+        m_strategyValues.at(p.first).begin(), m_strategyValues.at(p.first).end(),
+        static_cast<T>(0), std::plus<T>(), [&p](const auto &v) -> T {
+          return sqr(std::max(v.second - p.second, static_cast<T>(0)));
+        });
   }
   return liapValue;
 }
 
+template <class T> T MixedStrategyProfile<T>::GetRegret(const GameStrategy &p_strategy) const
+{
+  CheckVersion();
+  ComputePayoffs();
+  auto player = p_strategy->GetPlayer();
+  T best_other_payoff = maximize_function(exclude_value(player->GetStrategies(), p_strategy),
+                                          [this, &player](const auto &strategy) -> T {
+                                            return m_strategyValues.at(player).at(strategy);
+                                          });
+  return std::max(best_other_payoff - m_strategyValues.at(player).at(p_strategy),
+                  static_cast<T>(0));
+}
+
+template <class T> T MixedStrategyProfile<T>::GetRegret(const GamePlayer &p_player) const
+{
+  CheckVersion();
+  ComputePayoffs();
+  auto br_payoff =
+      maximize_function(p_player->GetStrategies(), [this, p_player](const auto &strategy) -> T {
+        return m_strategyValues.at(p_player).at(strategy);
+      });
+  return br_payoff - m_payoffs.at(p_player);
+}
+
+template <class T> T MixedStrategyProfile<T>::GetMaxRegret() const
+{
+  CheckVersion();
+  return maximize_function(GetGame()->GetPlayers(),
+                           [this](const auto &player) -> T { return this->GetRegret(player); });
+}
+
 template class MixedStrategyProfileRep<double>;
 template class MixedStrategyProfileRep<Rational>;
 

src/games/gameobject.h

@@ -188,7 +188,7 @@ template <class P, class T> class ElementCollection {
     }
     value_type operator*() const { return m_container->at(m_index); }
 
-    inline const P &GetOwner() const { return m_owner; }
+    const P &GetOwner() const { return m_owner; }
   };
 
   ElementCollection() = default;