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| ITK optimizers are generic classes, which can be used independently of registration. This example demonstrates use of the itk::AmoebaOptimizer class in optimizing a simple paraboloid function.
| | {{warning|1=The media wiki content on this page is no longer maintained. The examples presented on the https://itk.org/Wiki/* pages likely require ITK version 4.13 or earlier releases. In many cases, the examples on this page no longer conform to the best practices for modern ITK versions. |
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| Contributed by: Davis Vigneault
| | [https://itk.org/ITKExamples[ITK Sphinx Examples]] |
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| ==AmoebaOptimizerExample.cxx==
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| <source lang="cpp">
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| // Set properties pertinent to convergence
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| optimizer->SetMaximumNumberOfIterations( 100 );
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| optimizer->SetParametersConvergenceTolerance( 0.01 );
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| optimizer->SetFunctionConvergenceTolerance( 0.01 );
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| // Instantiate the cost function
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| // The cost function is a 2D paraboloid in the x-y plane
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| // with the equation f(x,y) = (x+5)^2+(y-7)^2 + 5
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| // and a global minimum at (x,y) = (-5, 7)
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| CostType::Pointer cost = CostType::New();
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| // Assign the cost function to the optimizer
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| optimizer->SetCostFunction( cost.GetPointer() );
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|
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| // Set the initial parameters of the cost function
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| OptimizerType::ParametersType initial(2);
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| initial[0] = 123;
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| initial[1] = -97.4;
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| optimizer->SetInitialPosition( initial );
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| // Begin the optimization!
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| optimizer->StartOptimization();
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| // Print out some information about the optimization
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| std::cout << "Position: " << optimizer->GetCurrentPosition() << std::endl;
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| std::cout << "Value: " << optimizer->GetValue() << std::endl;
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| // As expected, the position is near to (-5, 7) and the value to 5
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| // Position: [-5.003825599641884, 6.998563761340231]
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| // Value: 5.00002
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| return EXIT_SUCCESS;
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| }
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| </source>
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| ==ExampleCostFunction.h==
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| <source lang="cpp">
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| #ifndef __itkExampleCostFunction_h
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| #define __itkExampleCostFunction_h
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| #include "itkSingleValuedCostFunction.h"
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| namespace itk
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| {
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| class ExampleCostFunction :
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| public SingleValuedCostFunction
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| {
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| public:
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| /** Standard class typedefs. */
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| typedef ExampleCostFunction Self;
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| typedef SingleValuedCostFunction Superclass;
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| typedef SmartPointer<Self> Pointer;
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| typedef SmartPointer<const Self> ConstPointer;
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| /** Method for creation through the object factory. */
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| itkNewMacro(Self);
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| /** Run-time type information (and related methods). */
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| itkTypeMacro(ExampleCostFunction, SingleValuedCostfunction);
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| unsigned int GetNumberOfParameters(void) const { return 2; } // itk::CostFunction
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| MeasureType GetValue(const ParametersType & parameters) const {
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| return pow(parameters[0]+5, 2)+pow(parameters[1]-7, 2)+5;
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| }
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| void GetDerivative(const ParametersType & parameters,
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| DerivativeType & derivative ) const {
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| throw itk::ExceptionObject( __FILE__, __LINE__, "No derivative is available for this cost function.");
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| }
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| protected:
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| ExampleCostFunction(){};
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| ~ExampleCostFunction(){};
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| private:
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| ExampleCostFunction(const Self &); //purposely not implemented
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| void operator = (const Self &); //purposely not implemented
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| };
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| } // end namespace itk
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| #endif
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| </source>
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| {{ITKCMakeLists|{{SUBPAGENAME}}}}
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