tempest/src/storm-pomdp/transformer/BinaryPomdpTransformer.cpp

#include "storm-pomdp/transformer/BinaryPomdpTransformer.h"
#include <queue>

#include "storm/storage/sparse/ModelComponents.h"

#include "storm/utility/macros.h"
#include "storm/exceptions/NotSupportedException.h"

namespace storm {
    namespace transformer {

        template<typename  ValueType>
        BinaryPomdpTransformer<ValueType>::BinaryPomdpTransformer() {
            // Intentionally left empty
        }
        
        template<typename  ValueType>
        std::shared_ptr<storm::models::sparse::Pomdp<ValueType>> BinaryPomdpTransformer<ValueType>::transform(storm::models::sparse::Pomdp<ValueType> const& pomdp, bool transformSimple) const {
            auto data = transformTransitions(pomdp, transformSimple);
            storm::storage::sparse::ModelComponents<ValueType> components;
            components.stateLabeling = transformStateLabeling(pomdp, data);
            for (auto const& rewModel : pomdp.getRewardModels()) {
                components.rewardModels.emplace(rewModel.first, transformRewardModel(pomdp, rewModel.second, data));
            }
            components.transitionMatrix = std::move(data.simpleMatrix);
            components.observabilityClasses = std::move(data.simpleObservations);
            
            return std::make_shared<storm::models::sparse::Pomdp<ValueType>>(std::move(components), true);
        }
        
        struct BinaryPomdpTransformerRowGroup {
            BinaryPomdpTransformerRowGroup(uint64_t origState, uint64_t firstRow, uint64_t endRow, uint32_t origStateObservation) : origState(origState), firstRow(firstRow), endRow(endRow), origStateObservation(origStateObservation) {
                // Intentionally left empty.
            }

            uint64_t origState;
            uint64_t firstRow;
            uint64_t endRow;
            uint32_t origStateObservation;
            storm::storage::BitVector auxStateId;
            
            uint64_t size() const {
                return endRow - firstRow;
            }
            
            std::vector<BinaryPomdpTransformerRowGroup> split() const {
                assert(size() > 1);
                uint64_t midRow = firstRow + size()/2;
                std::vector<BinaryPomdpTransformerRowGroup> res;
                res.emplace_back(origState, firstRow, midRow, origStateObservation);
                storm::storage::BitVector newAuxStateId = auxStateId;
                newAuxStateId.resize(auxStateId.size() + 1, false);
                res.back().auxStateId = newAuxStateId;
                res.emplace_back(origState, midRow, endRow, origStateObservation);
                newAuxStateId.set(auxStateId.size(), true);
                res.back().auxStateId = newAuxStateId;
                return res;
            }
        };
        
        struct BinaryPomdpTransformerRowGroupCompare {
            bool operator () (BinaryPomdpTransformerRowGroup const& lhs, BinaryPomdpTransformerRowGroup const& rhs) const {
                if (lhs.origStateObservation == rhs.origStateObservation) {
                    return lhs.auxStateId < rhs.auxStateId;
                } else {
                    return lhs.origStateObservation < rhs.origStateObservation;
                }
            }
        };
        
        template<typename  ValueType>
        typename BinaryPomdpTransformer<ValueType>::TransformationData BinaryPomdpTransformer<ValueType>::transformTransitions(storm::models::sparse::Pomdp<ValueType> const& pomdp, bool transformSimple) const {
            auto const& matrix = pomdp.getTransitionMatrix();
            
            
            // Initialize a FIFO Queue that stores the start and the end of each row group
            std::queue<BinaryPomdpTransformerRowGroup> queue;
            for (uint64_t state = 0; state < matrix.getRowGroupCount(); ++state) {
                queue.emplace(state, matrix.getRowGroupIndices()[state], matrix.getRowGroupIndices()[state+1], pomdp.getObservation(state));
            }
            
            std::vector<uint32_t> newObservations;
            std::map<BinaryPomdpTransformerRowGroup, uint32_t, BinaryPomdpTransformerRowGroupCompare> observationMap;
            storm::storage::SparseMatrixBuilder<ValueType> builder(0,0,0,true,true);
            uint64_t currRow = 0;
            std::vector<uint64_t> origRowToSimpleRowMap(pomdp.getNumberOfChoices(), std::numeric_limits<uint64_t>::max());
            uint64_t currAuxState = queue.size();
            std::vector<uint64_t> origStates;

            while (!queue.empty()) {
                auto group = std::move(queue.front());
                queue.pop();
                
                // Get the observation
                uint64_t newObservation = observationMap.insert(std::make_pair(group, observationMap.size())).first->second;
                newObservations.push_back(newObservation);
                
                // Add matrix entries
                builder.newRowGroup(currRow);
                if (group.size() == 1) {
                    // Insert the row directly
                    for (auto const& entry : matrix.getRow(group.firstRow)) {
                        builder.addNextValue(currRow, entry.getColumn(), entry.getValue());
                    }
                    origRowToSimpleRowMap[group.firstRow] = currRow;
                    ++currRow;
                } else if (group.size() > 1) {
                    // Split the row group into two equally large parts
                    for (auto& splittedGroup : group.split()) {
                        // Check whether we can insert the row now or whether an auxiliary state is needed
                        if (splittedGroup.size() == 1 && (!transformSimple || matrix.getRow(splittedGroup.firstRow).getNumberOfEntries() < 2)) {
                            for (auto const& entry : matrix.getRow(splittedGroup.firstRow)) {
                                builder.addNextValue(currRow, entry.getColumn(), entry.getValue());
                            }
                            origRowToSimpleRowMap[splittedGroup.firstRow] = currRow;
                            ++currRow;
                        } else {
                            queue.push(std::move(splittedGroup));
                            builder.addNextValue(currRow, currAuxState, storm::utility::one<ValueType>());
                            ++currAuxState;
                            ++currRow;
                        }
                    }
                }
                // Nothing to be done if group has size zero
                origStates.push_back(group.origState);
            }
            
            TransformationData result;
            result.simpleMatrix = builder.build(currRow, currAuxState, currAuxState);
            result.simpleObservations = std::move(newObservations);
            result.originalToSimpleChoiceMap = std::move(origRowToSimpleRowMap);
            result.simpleStateToOriginalState = std::move(origStates);
            return result;
        }
        
        
        template<typename  ValueType>
        storm::models::sparse::StateLabeling BinaryPomdpTransformer<ValueType>::transformStateLabeling(storm::models::sparse::Pomdp<ValueType> const& pomdp, TransformationData const& data) const {
            storm::models::sparse::StateLabeling labeling(data.simpleMatrix.getRowGroupCount());
            for (auto const& labelName : pomdp.getStateLabeling().getLabels()) {
                storm::storage::BitVector newStates = pomdp.getStateLabeling().getStates(labelName);
                newStates.resize(data.simpleMatrix.getRowGroupCount(), false);
                for (uint64_t newState = pomdp.getNumberOfStates(); newState < data.simpleMatrix.getRowGroupCount(); ++newState ) {
                    newStates.set(newState, newStates[data.simpleStateToOriginalState[newState]]);
                }
                labeling.addLabel(labelName, std::move(newStates));

            }
            return labeling;
        }
        
        template<typename  ValueType>
        storm::models::sparse::StandardRewardModel<ValueType> BinaryPomdpTransformer<ValueType>::transformRewardModel(storm::models::sparse::Pomdp<ValueType> const& pomdp, storm::models::sparse::StandardRewardModel<ValueType> const& rewardModel, TransformationData const& data) const {
            boost::optional<std::vector<ValueType>> stateRewards, actionRewards;
            if (rewardModel.hasStateRewards()) {
                stateRewards = rewardModel.getStateRewardVector();
                stateRewards.get().resize(data.simpleMatrix.getRowGroupCount(), storm::utility::zero<ValueType>());
            }
            if (rewardModel.hasStateActionRewards()) {
                actionRewards = std::vector<ValueType>(data.simpleMatrix.getRowCount(), storm::utility::zero<ValueType>());
                for (uint64_t pomdpChoice = 0; pomdpChoice < pomdp.getNumberOfChoices(); ++pomdpChoice) {
                    STORM_LOG_ASSERT(data.originalToSimpleChoiceMap[pomdpChoice] < data.simpleMatrix.getRowCount(), "Invalid entry in map for choice " << pomdpChoice);
                    actionRewards.get()[data.originalToSimpleChoiceMap[pomdpChoice]] = rewardModel.getStateActionReward(pomdpChoice);
                }
            }
            STORM_LOG_THROW(!rewardModel.hasTransitionRewards(), storm::exceptions::NotSupportedException, "Transition rewards are currently not supported.");
            return storm::models::sparse::StandardRewardModel<ValueType>(std::move(stateRewards), std::move(actionRewards));
        }
        
        
        template class BinaryPomdpTransformer<storm::RationalNumber>;

        template
        class BinaryPomdpTransformer<double>;
    }
}