[shark] 39/58: fixed bugs in PolynomialMutation and SimulatedBinaryCrossover by checking with Debs original code. Now NSGAII and SMS-EMOA behave reasonable

[Ghislain Vaillant]

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ghisvail-guest pushed a commit to branch master
in repository shark.

commit 5c950d25eccba2d7077a10cf86388d6f20a7b1d9
Author: Oswin <oswin.krause at di.ku.dk>
Date:   Tue Feb 9 07:44:38 2016 +0100

    fixed bugs in PolynomialMutation and SimulatedBinaryCrossover by checking with Debs original code. Now NSGAII and SMS-EMOA behave reasonable
---
 .../Operators/Mutation/PolynomialMutation.h        | 37 +++++++--------
 .../Recombination/SimulatedBinaryCrossover.h       | 52 +++++++++++-----------
 2 files changed, 41 insertions(+), 48 deletions(-)

diff --git a/include/shark/Algorithms/DirectSearch/Operators/Mutation/PolynomialMutation.h b/include/shark/Algorithms/DirectSearch/Operators/Mutation/PolynomialMutation.h
index 8cbf1f3..051ae20 100644
--- a/include/shark/Algorithms/DirectSearch/Operators/Mutation/PolynomialMutation.h
+++ b/include/shark/Algorithms/DirectSearch/Operators/Mutation/PolynomialMutation.h
@@ -42,7 +42,7 @@ namespace shark {
 	struct PolynomialMutator {
 
 		/// \brief Default c'tor.
-		PolynomialMutator() : m_nm( 20.0 ) {}
+		PolynomialMutator() : m_nm( 25.0 ) {}
 
 		/// \brief Initializes the operator for the supplied box-constraints
 		void init( RealVector const& lower, RealVector const& upper ) {
@@ -58,34 +58,29 @@ namespace shark {
 		/// \param [in,out] ind Individual to be mutated.
 		template<typename IndividualType>
 		void operator()( IndividualType & ind )const{
-			double delta, deltaQ, expp,  u = 0.;
-			
 			RealVector& point = ind.searchPoint();
            
 			for( unsigned int i = 0; i < point.size(); i++ ) {
 
 				if( Rng::coinToss( m_prob ) ) {
-					u  = Rng::uni( 0., 1. );
-					if( point[i] <= m_lower( i ) || point[i] >= m_upper( i ) ) { 
-						point[i] = u * (m_upper( i ) - m_lower( i ) ) + m_lower( i );
+					if( point[i] < m_lower( i ) || point[i] > m_upper( i ) ) { 
+						point[i] = Rng::uni(m_lower(i),m_upper(i));
 					} else {
-						// Calculate delta
-						if( (point[i] - m_lower( i ) ) < (m_upper( i ) - point[i]) )
-							delta = (point[i] - m_lower( i ) ) / (m_upper( i ) - m_lower( i ) );
-						else
-							delta = (m_upper( i ) - point[i]) / (m_upper( i ) - m_lower( i ));
-
-						delta = 1. - delta;
-						expp  = (m_nm + 1.);
-						delta = ::pow(delta , expp);
-						expp  = 1. / expp;
-
+						// Calculate normalized distance from boundaries
+						double delta1 = (m_upper( i ) - point[i]) / (m_upper( i ) - m_lower( i ));
+						double delta2 = (point[i] - m_lower( i ) ) / (m_upper( i ) - m_lower( i ));
+						
+						//compute change in delta
+						double deltaQ=0;
+						double u = Rng::uni(0,1);
 						if( u <= .5 ) {
-							deltaQ =  2. * u + (1 - 2. * u) * delta;
-							deltaQ = ::pow(deltaQ, expp) - 1. ;
+							double delta = std::pow(delta1 , m_nm + 1.);
+							deltaQ =  2.0 * u + (1.0 - 2.0 * u) * delta;
+							deltaQ = std::pow(deltaQ, 1.0/(m_nm+1.0)) - 1. ;
 						} else {
-							deltaQ = 2. - 2. * u + 2. * (u  - .5) * delta;
-							deltaQ = 1. - ::pow(deltaQ , expp);
+							double delta = std::pow(delta2 , m_nm + 1.);
+							deltaQ = 2 * (1- u) + 2. * (u  - .5) * delta;
+							deltaQ = 1. - std::pow(deltaQ , 1.0/(m_nm+1.0));
 						}
 
 						point[i] += deltaQ * (m_upper( i ) - m_lower( i ) );
diff --git a/include/shark/Algorithms/DirectSearch/Operators/Recombination/SimulatedBinaryCrossover.h b/include/shark/Algorithms/DirectSearch/Operators/Recombination/SimulatedBinaryCrossover.h
index f659a3e..befd3b0 100644
--- a/include/shark/Algorithms/DirectSearch/Operators/Recombination/SimulatedBinaryCrossover.h
+++ b/include/shark/Algorithms/DirectSearch/Operators/Recombination/SimulatedBinaryCrossover.h
@@ -77,35 +77,33 @@ namespace shark {
 					y2 = point2[i];
 				}
 				
-				double betaQ = 0.0;
-				if( std::abs(y2 - y1) > 1E-7 ) {					
-					// Find beta value
-					double beta = 0;
-					if( (y1 - m_lower( i )) > (m_upper( i ) - y2) )
-						beta = 1 + 2 * (m_upper( i ) - y2) / (y2 - y1);
-					else
-						beta = 1 + 2 * (y1 - m_lower( i )) / (y2 - y1);
-
-
-					double expp = m_nc + 1.;
-					// Find alpha
-					double alpha = 2. - std::pow(1.0/beta , expp);
-					double u = Rng::uni( 0., 1. );
-
-					if( u <= 1. / alpha ) {
-						alpha *= u;
-						betaQ = std::pow( alpha, 1.0/expp );
-					} else {
-						alpha *= u;
-						alpha = 1. / (2. - alpha);
-						betaQ = std::pow( alpha, 1.0/expp );
-					}
-				} else { // if genes are equal -> from Deb's implementation, not contained in any paper
-					betaQ = 1.;
+				double betaQ1 = 0.0;
+				double betaQ2 = 0.0;
+				if( std::abs(y2 - y1) < 1E-7 )continue;//equal
+				
+				// Find beta value2
+				double beta1 = 1 + 2 * (y1 - m_lower( i )) / (y2 - y1);
+				double beta2 = 1 + 2 * (m_upper( i ) - y2) / (y2 - y1);
+				double expp = m_nc + 1.;
+				// Find alpha
+				double alpha1 = 2. - std::pow(beta1 , -expp);
+				double alpha2 = 2. - std::pow(beta2 , -expp);
+
+				double u = Rng::uni( 0., 1. );
+				alpha1 *=u;
+				alpha2 *=u;
+				if( u > 1. / alpha1 ) {
+					alpha1 = 1. / (2. - alpha1);
+				}
+				if( u > 1. / alpha2 ) {
+					alpha2 = 1. / (2. - alpha2);
 				}
+				betaQ1 = std::pow( alpha1, 1.0/expp );
+				betaQ2 = std::pow( alpha2, 1.0/expp );
 
-				point1[i] = 0.5 * ((y1 + y2) - betaQ * (y2 - y1));
-				point2[i] = 0.5 * ((y1 + y2) + betaQ * (y2 - y1));
+				//recombine points
+				point1[i] = 0.5 * ((y1 + y2) - betaQ1 * (y2 - y1));
+				point2[i] = 0.5 * ((y1 + y2) + betaQ2 * (y2 - y1));
 				// randomly swap loci
 				if( Rng::coinToss() ) std::swap(point1[i], point2[i]);
 

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