gtsam/gtsam_unstable/discrete/Scheduler.cpp

/*
 * Scheduler.h
 * @brief an example how inference can be used for scheduling qualifiers
 * @date Mar 26, 2011
 * @author Frank Dellaert
 */

#include <gtsam_unstable/discrete/Scheduler.h>
#include <gtsam/discrete/DiscreteFactorGraph.h>
#include <gtsam/discrete/DiscreteSequentialSolver.h>
#include <gtsam/base/debug.h>
#include <gtsam/base/timing.h>

#include <boost/tokenizer.hpp>
#include <boost/foreach.hpp>

#include <fstream>
#include <iomanip>
#include <cmath>

namespace gtsam {

  using namespace std;

  Scheduler::Scheduler(size_t maxNrStudents, const string& filename):
      maxNrStudents_(maxNrStudents)
  {
    typedef boost::tokenizer<boost::escaped_list_separator<char> > Tokenizer;

    // open file
    ifstream is(filename.c_str());
    if (!is) {
      cerr << "Scheduler: could not open file " << filename << endl;
      throw runtime_error("Scheduler: could not open file " + filename);
    }

    string line; // buffer

    // process first line with faculty
    if (getline(is, line, '\r')) {
      Tokenizer tok(line);
      Tokenizer::iterator it = tok.begin();
      for (++it; it != tok.end(); ++it)
        addFaculty(*it);
    }

    // for all remaining lines
    size_t count = 0;
    while (getline(is, line, '\r')) {
      if (count++ > 100) throw runtime_error("reached 100 lines, exiting");
      Tokenizer tok(line);
      Tokenizer::iterator it = tok.begin();
      addSlot(*it++); // add slot
      // add availability
      for (; it != tok.end(); ++it)
        available_ += (it->empty()) ? "0 " : "1 ";
      available_ += '\n';
    }
  } // constructor

  /** addStudent has to be called after adding slots and faculty */
  void Scheduler::addStudent(const string& studentName,
      const string& area1, const string& area2,
      const string& area3, const string& advisor) {
    assert(nrStudents()<maxNrStudents_);
    assert(facultyInArea_.count(area1));
    assert(facultyInArea_.count(area2));
    assert(facultyInArea_.count(area3));
    size_t advisorIndex = facultyIndex_[advisor];
    Student student(nrFaculty(), advisorIndex);
    student.name_ = studentName;
    // We fix the ordering by assigning a higher index to the student
    // and numbering the areas lower
    Index j = 3*maxNrStudents_ + nrStudents();
    student.key_ = DiscreteKey(j, nrTimeSlots());
    Index base = 3*nrStudents();
    student.keys_[0] = DiscreteKey(base+0, nrFaculty());
    student.keys_[1] = DiscreteKey(base+1, nrFaculty());
    student.keys_[2] = DiscreteKey(base+2, nrFaculty());
    student.areaName_[0] = area1;
    student.areaName_[1] = area2;
    student.areaName_[2] = area3;
    students_.push_back(student);
    }

  /** get key for student and area, 0 is time slot itself */
  const DiscreteKey& Scheduler::key(size_t s, boost::optional<size_t> area) const {
    return area ? students_[s].keys_[*area] : students_[s].key_;
  }

  const string& Scheduler::studentName(size_t i) const {
    assert(i<nrStudents());
    return students_[i].name_;
  }

  const DiscreteKey& Scheduler::studentKey(size_t i) const {
    assert(i<nrStudents());
    return students_[i].key_;
  }

  const string& Scheduler::studentArea(size_t i, size_t area) const {
    assert(i<nrStudents());
    return students_[i].areaName_[area];
  }

  /** Add student-specific constraints to the graph */
  void Scheduler::addStudentSpecificConstraints(size_t i, boost::optional<size_t> slot) {
    bool debug = ISDEBUG("Scheduler::buildGraph");

    assert(i<nrStudents());
    const Student& s = students_[i];

    if (!slot && !slotsAvailable_.empty()) {
      if (debug) cout << "Adding availability of slots" << endl;
      assert(slotsAvailable_.size()==s.key_.second);
      CSP::add(s.key_, slotsAvailable_);
    }

    // For all areas
    for (size_t area = 0; area < 3; area++) {

      DiscreteKey areaKey = s.keys_[area];
      const string& areaName = s.areaName_[area];

      if (debug) cout << "Area constraints " << areaName << endl;
      assert(facultyInArea_[areaName].size()==areaKey.second);
      CSP::add(areaKey, facultyInArea_[areaName]);

      if (debug) cout << "Advisor constraint " << areaName << endl;
      assert(s.advisor_.size()==areaKey.second);
      CSP::add(areaKey, s.advisor_);

      if (debug) cout << "Availability of faculty " << areaName << endl;
      if (slot) {
        // get all constraints then specialize to slot
        size_t dummyIndex = maxNrStudents_*3+maxNrStudents_;
        DiscreteKey dummy(dummyIndex, nrTimeSlots());
        Potentials::ADT p(dummy & areaKey, available_); // available_ is Doodle string
        Potentials::ADT q = p.choose(dummyIndex, *slot);
        DiscreteFactor::shared_ptr f(new DecisionTreeFactor(areaKey, q));
        CSP::push_back(f);
      } else {
        CSP::add(s.key_, areaKey, available_); // available_ is Doodle string
      }
    }

    // add mutex
    if (debug) cout << "Mutex for faculty" << endl;
    addAllDiff(s.keys_[0] & s.keys_[1] & s.keys_[2]);
  }


  /** Main routine that builds factor graph */
  void Scheduler::buildGraph(size_t mutexBound) {
    bool debug = ISDEBUG("Scheduler::buildGraph");

    if (debug) cout << "Adding student-specific constraints" << endl;
    for (size_t i = 0; i < nrStudents(); i++)
      addStudentSpecificConstraints(i);

    // special constraint for MN
    if (studentName(0) == "Michael N") CSP::add(studentKey(0),
        "0 0 0 0  1 1 1 1  1 1 1 1  1 1 1 1  1 1 1 1");

    if (!mutexBound) {
      DiscreteKeys dkeys;
      BOOST_FOREACH(const Student& s, students_)
        dkeys.push_back(s.key_);
      addAllDiff(dkeys);
    } else {
      if (debug) cout << "Mutex for Students" << endl;
      for (size_t i1 = 0; i1 < nrStudents(); i1++) {
        // if mutexBound=1, we only mutex with next student
        size_t bound = min((i1 + 1 + mutexBound), nrStudents());
        for (size_t i2 = i1 + 1; i2 < bound; i2++) {
          addAllDiff(studentKey(i1), studentKey(i2));
        }
      }
    }
  } // buildGraph

  /** print */
  void Scheduler::print(const string& s) const {

    cout << s << " Faculty:" << endl;
    BOOST_FOREACH(const string& name, facultyName_)
            cout << name << '\n';
    cout << endl;

    cout << s << " Slots:\n";
    size_t i = 0;
    BOOST_FOREACH(const string& name, slotName_)
            cout << i++ << " " << name << endl;
    cout << endl;

    cout << "Availability:\n" << available_ << '\n';

    cout << s << " Area constraints:\n";
    BOOST_FOREACH(const FacultyInArea::value_type& it, facultyInArea_)
          {
            cout << setw(12) << it.first << ": ";
            BOOST_FOREACH(double v, it.second)
                    cout << v << " ";
            cout << '\n';
          }
    cout << endl;

    cout << s << " Students:\n";
    BOOST_FOREACH (const Student& student, students_)
            student.print();
    cout << endl;

    CSP::print(s + " Factor graph");
    cout << endl;
  } // print

  /** Print readable form of assignment */
  void Scheduler::printAssignment(sharedValues assignment) const {
    // Not intended to be general! Assumes very particular ordering !
    cout << endl;
    for (size_t s = 0; s < nrStudents(); s++) {
      Index j = 3*maxNrStudents_ + s;
      size_t slot = assignment->at(j);
      cout << studentName(s) << " slot: " << slotName_[slot] << endl;
      Index base = 3*s;
      for (size_t area = 0; area < 3; area++) {
        size_t faculty = assignment->at(base+area);
        cout << setw(12) << studentArea(s,area) << ": " << facultyName_[faculty]
            << endl;
      }
      cout << endl;
    }
  }

  /** Special print for single-student case */
  void Scheduler::printSpecial(sharedValues assignment) const {
    Values::const_iterator it = assignment->begin();
    for (size_t area = 0; area < 3; area++, it++) {
      size_t f = it->second;
      cout << setw(12) << studentArea(0,area) << ": " << facultyName_[f] << endl;
    }
    cout << endl;
  }

  /** Accumulate faculty stats */
  void Scheduler::accumulateStats(sharedValues assignment, vector<
      size_t>& stats) const {
    for (size_t s = 0; s < nrStudents(); s++) {
      Index base = 3*s;
      for (size_t area = 0; area < 3; area++) {
        size_t f = assignment->at(base+area);
        assert(f<stats.size());
        stats[f]++;
      } // area
    } // s
  }

  /** Eliminate, return a Bayes net */
  DiscreteBayesNet::shared_ptr Scheduler::eliminate() const {
    gttic(my_solver);
    DiscreteSequentialSolver solver(*this);
    gttoc(my_solver);
    gttic(my_eliminate);
    DiscreteBayesNet::shared_ptr chordal = solver.eliminate();
    gttoc(my_eliminate);
    return chordal;
  }

  /** Find the best total assignment - can be expensive */
  Scheduler::sharedValues Scheduler::optimalAssignment() const {
    DiscreteBayesNet::shared_ptr chordal = eliminate();

    if (ISDEBUG("Scheduler::optimalAssignment")) {
      DiscreteBayesNet::const_reverse_iterator it = chordal->rbegin();
      const Student & student = students_.front();
      cout << endl;
      (*it)->print(student.name_);
    }

    gttic(my_optimize);
    sharedValues mpe = optimize(*chordal);
    gttoc(my_optimize);
    return mpe;
  }

  /** find the assignment of students to slots with most possible committees */
  Scheduler::sharedValues Scheduler::bestSchedule() const {
    sharedValues best;
    throw runtime_error("bestSchedule not implemented");
    return best;
  }

  /** find the corresponding most desirable committee assignment */
  Scheduler::sharedValues Scheduler::bestAssignment(
      sharedValues bestSchedule) const {
    sharedValues best;
    throw runtime_error("bestAssignment not implemented");
    return best;
  }

} // gtsam