23/02/07 modifications

git-svn-id: svn://scm.gforge.inria.fr/svnroot/paradiseo@186 331e1502-861f-0410-8da2-ba01fb791d7f

branches/paradiseo-moeo-1.0/src/metric/moeoHypervolumeBinaryMetric.h

@@ -0,0 +1,139 @@
+// -*- mode: c++; c-indent-level: 4; c++-member-init-indent: 8; comment-column: 35; -*-
+
+//-----------------------------------------------------------------------------
+// moeoHypervolumeBinaryMetric.h
+// (c) OPAC Team (LIFL), Dolphin Project (INRIA), 2007
+/*
+    This library...
+
+    Contact: paradiseo-help@lists.gforge.inria.fr, http://paradiseo.gforge.inria.fr
+ */
+//-----------------------------------------------------------------------------
+
+#ifndef MOEOHYPERVOLUMEBINARYMETRIC_H_
+#define MOEOHYPERVOLUMEBINARYMETRIC_H_
+
+#include <stdexcept>
+#include <metric/moeoMetric.h>
+
+/**
+ * Hypervolume binary metric allowing to compare two objective vectors as proposed in
+ * Zitzler E., Künzli S.: Indicator-Based Selection in Multiobjective Search. In Parallel Problem Solving from Nature (PPSN VIII).
+ * Lecture Notes in Computer Science 3242, Springer, Birmingham, UK pp.832–842 (2004).
+ * This indicator is based on the hypervolume concept introduced in 
+ * Zitzler, E., Thiele, L.: Multiobjective Optimization Using Evolutionary Algorithms - A Comparative Case Study.
+ * Parallel Problem Solving from Nature (PPSN-V), pp.292-301 (1998).
+ */
+template < class ObjectiveVector >
+class moeoHypervolumeBinaryMetric : public moeoNormalizedSolutionVsSolutionBinaryMetric < ObjectiveVector, double >
+{
+public:
+
+	/**
+	 * Ctor
+	 * @param _rho value used to compute the reference point from the worst values for each objective (default : 1.1)
+	 */
+	moeoHypervolumeBinaryMetric(double _rho = 1.1) : rho(_rho)
+	{
+		// not-a-maximization problem check
+		for (unsigned i=0; i<ObjectiveVector::Traits::nObjectives(); i++)
+		{
+			if (ObjectiveVector::Traits::maximizing(i))
+			{
+				throw std::runtime_error("Hypervolume binary metric not yet implemented for a maximization problem in moeoHypervolumeBinaryMetric");
+			}
+		}
+		// consistency check
+		if (rho < 1)
+		{
+			cout << "Warning, value used to compute the reference point rho for the hypervolume calculation must not be smaller than 1" << endl;
+			cout << "Adjusted to 1" << endl;
+			rho = 1;
+		}
+	}
+	
+	
+	/**
+	 * Returns the volume of the space that is dominated by _o2 but not by _o1 with respect to a reference point computed using rho.
+	 * @warning don't forget to set the bounds for every objective before the call of this function
+	 * @param _o1 the first objective vector
+	 * @param _o2 the second objective vector
+	 */
+	double operator()(const ObjectiveVector & _o1, const ObjectiveVector & _o2)
+	{
+		double result;
+		// if _o1 dominates _o2
+		if ( paretoComparator(_o1,_o2) )
+		{
+			result = - hypervolume(_o1, _o2, ObjectiveVector::Traits::nObjectives()-1);
+		}
+		else
+		{
+			result = hypervolume(_o2, _o1, ObjectiveVector::Traits::nObjectives()-1);
+		}
+		return result;
+	}
+
+
+private:
+
+	/** value used to compute the reference point from the worst values for each objective */
+	double rho;
+	/** the bounds for every objective */
+	using moeoNormalizedSolutionVsSolutionBinaryMetric < ObjectiveVector, double > :: bounds;
+	/** Functor to compare two objective vectors according to Pareto dominance relation */
+	moeoParetoObjectiveVectorComparator < ObjectiveVector > paretoComparator;
+	
+	/**
+	 * Returns the volume of the space that is dominated by _o2 but not by _o1 with respect to a reference point computed using rho for the objective _obj.
+	 * @param _o1 the first objective vector
+	 * @param _o2 the second objective vector
+	 * @param _obj the objective index
+	 * @param _flag used for iteration, if _flag=true _o2 is not talen into account (default : false)
+	 */
+	double hypervolume(const ObjectiveVector & _o1, const ObjectiveVector & _o2, const unsigned _obj, const bool _flag = false)
+	{
+		double result;
+		double range = rho * bounds[_obj].range();
+		double max = bounds[_obj].minimum() + range;
+		// value of _1 for the objective _obj
+		double v1 = _o1[_obj];
+		// value of _2 for the objective _obj (if _flag=true, v2=max)
+		double v2;
+		if (_flag)
+		{
+			v2 = max;
+		}
+		else
+		{
+			v2 = _o2[_obj];
+		}
+		// computation of the volume
+		if (_obj == 0)
+		{
+			if (v1 < v2)
+			{
+				result = (v2 - v1) / range;
+			}
+			else
+			{
+				result = 0;
+			}
+		}
+		else
+		{
+			if (v1 < v2)
+			{
+				result = ( hypervolume(_o1, _o2, _obj-1, true) * (v2 - v1) / range ) + ( hypervolume(_o1, _o2, _obj-1) * (max - v2) / range );
+			}
+			else
+			{
+				result = hypervolume(_o1, _o2, _obj-1) * (max - v2) / range;
+			}
+		}
+		return result;
+	}
+	
+};
+
+#endif /*MOEOHYPERVOLUMEBINARYMETRIC_H_*/