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With inspiration from other libraries
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.math3.optim;
import org.apache.commons.math3.util.Incrementor;
import org.apache.commons.math3.exception.TooManyEvaluationsException;
import org.apache.commons.math3.exception.TooManyIterationsException;
/**
* Base class for implementing optimizers.
* It contains the boiler-plate code for counting the number of evaluations
* of the objective function and the number of iterations of the algorithm,
* and storing the convergence checker.
* It is not a "user" class.
*
* @param Type of the point/value pair returned by the optimization
* algorithm.
*
* @since 3.1
*/
public abstract class BaseOptimizer {
/** Evaluations counter. */
protected final Incrementor evaluations;
/** Iterations counter. */
protected final Incrementor iterations;
/** Convergence checker. */
private final ConvergenceChecker checker;
/**
* @param checker Convergence checker.
*/
protected BaseOptimizer(ConvergenceChecker checker) {
this(checker, 0, Integer.MAX_VALUE);
}
/**
* @param checker Convergence checker.
* @param maxEval Maximum number of objective function evaluations.
* @param maxIter Maximum number of algorithm iterations.
*/
protected BaseOptimizer(ConvergenceChecker checker,
int maxEval,
int maxIter) {
this.checker = checker;
evaluations = new Incrementor(maxEval, new MaxEvalCallback());
iterations = new Incrementor(maxIter, new MaxIterCallback());
}
/**
* Gets the maximal number of function evaluations.
*
* @return the maximal number of function evaluations.
*/
public int getMaxEvaluations() {
return evaluations.getMaximalCount();
}
/**
* Gets the number of evaluations of the objective function.
* The number of evaluations corresponds to the last call to the
* {@code optimize} method. It is 0 if the method has not been
* called yet.
*
* @return the number of evaluations of the objective function.
*/
public int getEvaluations() {
return evaluations.getCount();
}
/**
* Gets the maximal number of iterations.
*
* @return the maximal number of iterations.
*/
public int getMaxIterations() {
return iterations.getMaximalCount();
}
/**
* Gets the number of iterations performed by the algorithm.
* The number iterations corresponds to the last call to the
* {@code optimize} method. It is 0 if the method has not been
* called yet.
*
* @return the number of evaluations of the objective function.
*/
public int getIterations() {
return iterations.getCount();
}
/**
* Gets the convergence checker.
*
* @return the object used to check for convergence.
*/
public ConvergenceChecker getConvergenceChecker() {
return checker;
}
/**
* Stores data and performs the optimization.
*
* The list of parameters is open-ended so that sub-classes can extend it
* with arguments specific to their concrete implementations.
*
* When the method is called multiple times, instance data is overwritten
* only when actually present in the list of arguments: when not specified,
* data set in a previous call is retained (and thus is optional in
* subsequent calls).
*
* Important note: Subclasses must override
* {@link #parseOptimizationData(OptimizationData[])} if they need to register
* their own options; but then, they must also call
* {@code super.parseOptimizationData(optData)} within that method.
*
* @param optData Optimization data.
* This method will register the following data:
*
* - {@link MaxEval}
* - {@link MaxIter}
*
* @return a point/value pair that satisfies the convergence criteria.
* @throws TooManyEvaluationsException if the maximal number of
* evaluations is exceeded.
* @throws TooManyIterationsException if the maximal number of
* iterations is exceeded.
*/
public PAIR optimize(OptimizationData... optData)
throws TooManyEvaluationsException,
TooManyIterationsException {
// Parse options.
parseOptimizationData(optData);
// Reset counters.
evaluations.resetCount();
iterations.resetCount();
// Perform optimization.
return doOptimize();
}
/**
* Performs the optimization.
*
* @return a point/value pair that satisfies the convergence criteria.
* @throws TooManyEvaluationsException if the maximal number of
* evaluations is exceeded.
* @throws TooManyIterationsException if the maximal number of
* iterations is exceeded.
*/
public PAIR optimize()
throws TooManyEvaluationsException,
TooManyIterationsException {
// Reset counters.
evaluations.resetCount();
iterations.resetCount();
// Perform optimization.
return doOptimize();
}
/**
* Performs the bulk of the optimization algorithm.
*
* @return the point/value pair giving the optimal value of the
* objective function.
*/
protected abstract PAIR doOptimize();
/**
* Increment the evaluation count.
*
* @throws TooManyEvaluationsException if the allowed evaluations
* have been exhausted.
*/
protected void incrementEvaluationCount()
throws TooManyEvaluationsException {
evaluations.incrementCount();
}
/**
* Increment the iteration count.
*
* @throws TooManyIterationsException if the allowed iterations
* have been exhausted.
*/
protected void incrementIterationCount()
throws TooManyIterationsException {
iterations.incrementCount();
}
/**
* Scans the list of (required and optional) optimization data that
* characterize the problem.
*
* @param optData Optimization data.
* The following data will be looked for:
*
* - {@link MaxEval}
* - {@link MaxIter}
*
*/
protected void parseOptimizationData(OptimizationData... optData) {
// The existing values (as set by the previous call) are reused if
// not provided in the argument list.
for (OptimizationData data : optData) {
if (data instanceof MaxEval) {
evaluations.setMaximalCount(((MaxEval) data).getMaxEval());
continue;
}
if (data instanceof MaxIter) {
iterations.setMaximalCount(((MaxIter) data).getMaxIter());
continue;
}
}
}
/**
* Defines the action to perform when reaching the maximum number
* of evaluations.
*/
private static class MaxEvalCallback
implements Incrementor.MaxCountExceededCallback {
/**
* {@inheritDoc}
* @throws TooManyEvaluationsException
*/
public void trigger(int max) {
throw new TooManyEvaluationsException(max);
}
}
/**
* Defines the action to perform when reaching the maximum number
* of evaluations.
*/
private static class MaxIterCallback
implements Incrementor.MaxCountExceededCallback {
/**
* {@inheritDoc}
* @throws TooManyIterationsException
*/
public void trigger(int max) {
throw new TooManyIterationsException(max);
}
}
}