new version

git-svn-id: svn://scm.gforge.inria.fr/svnroot/paradiseo@267 331e1502-861f-0410-8da2-ba01fb791d7f

trunk/paradiseo-moeo/src/moeoCrowdingDistanceDiversityAssignment.h

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+// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
+
+//-----------------------------------------------------------------------------
+// moeoCrowdingDistanceDiversityAssignment.h
+// (c) OPAC Team (LIFL), Dolphin Project (INRIA), 2007
+/*
+    This library...
+
+    Contact: paradiseo-help@lists.gforge.inria.fr, http://paradiseo.gforge.inria.fr
+ */
+//-----------------------------------------------------------------------------
+
+#ifndef MOEOCROWDINGDISTANCEDIVERSITYASSIGNMENT_H_
+#define MOEOCROWDINGDISTANCEDIVERSITYASSIGNMENT_H_
+
+#include <eoPop.h>
+#include <moeoComparator.h>
+#include <moeoDiversityAssignment.h>
+
+/**
+ * Diversity assignment sheme based on crowding distance proposed in:
+ * K. Deb, A. Pratap, S. Agarwal, T. Meyarivan, "A Fast and Elitist Multi-Objective Genetic Algorithm: NSGA-II", IEEE Transactions on Evolutionary Computation, vol. 6, no. 2 (2002).
+ * This strategy is, for instance, used in NSGA-II.
+ */
+template < class MOEOT >
+class moeoCrowdingDistanceDiversityAssignment : public moeoDiversityAssignment < MOEOT >
+{
+public:
+
+    /** the objective vector type of the solutions */
+    typedef typename MOEOT::ObjectiveVector ObjectiveVector;
+
+
+    /**
+     * Returns a big value (regarded as infinite)
+     */
+    double inf() const
+    {
+        return std::numeric_limits<double>::max();
+    }
+
+
+    /**
+     * Computes diversity values for every solution contained in the population _pop
+     * @param _pop the population
+     */
+    void operator()(eoPop < MOEOT > & _pop)
+    {
+        if (_pop.size() <= 2)
+        {
+            for (unsigned i=0; i<_pop.size(); i++)
+            {
+                _pop[i].diversity(inf());
+            }
+        }
+        else
+        {
+            setDistances(_pop);
+        }
+    }
+
+
+    /**
+     * @warning NOT IMPLEMENTED, DO NOTHING !
+     * Updates the diversity values of the whole population _pop by taking the deletion of the objective vector _objVec into account.
+     * @param _pop the population
+     * @param _objVec the objective vector
+     * @warning NOT IMPLEMENTED, DO NOTHING !
+     */
+    void updateByDeleting(eoPop < MOEOT > & _pop, ObjectiveVector & _objVec)
+    {
+        cout << "WARNING : updateByDeleting not implemented in moeoCrowdingDiversityAssignment" << endl;
+    }
+
+
+private:
+
+    /**
+     * Sets the distance values
+     * @param _pop the population
+     */
+    void setDistances (eoPop < MOEOT > & _pop)
+    {
+        double min, max, distance;
+        unsigned nObjectives = MOEOT::ObjectiveVector::nObjectives();
+        // set diversity to 0
+        for (unsigned i=0; i<_pop.size(); i++)
+        {
+            _pop[i].diversity(0);
+        }
+        // for each objective
+        for (unsigned obj=0; obj<nObjectives; obj++)
+        {
+            // comparator
+            moeoOneObjectiveComparator < MOEOT > comp(obj);
+            // sort
+            std::sort(_pop.begin(), _pop.end(), comp);
+            // min & max
+            min = _pop[0].objectiveVector()[obj];
+            max = _pop[_pop.size()-1].objectiveVector()[obj];
+            // set the diversity value to infiny for min and max
+            _pop[0].diversity(inf());
+            _pop[_pop.size()-1].diversity(inf());
+            for (unsigned i=1; i<_pop.size()-1; i++)
+            {
+                distance = (_pop[i+1].objectiveVector()[obj] - _pop[i-1].objectiveVector()[obj]) / (max-min);
+                _pop[i].diversity(_pop[i].diversity() + distance);
+            }
+        }
+    }
+
+};
+
+#endif /*MOEOCROWDINGDISTANCEDIVERSITYASSIGNMENT_H_*/