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Java example source code file (LinearOptimizer.java)

This example Java source code file (LinearOptimizer.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

collection, linearconstraintset, linearobjectivefunction, linearoptimizer, multivariateoptimizer, nonnegativeconstraint, optimizationdata, override, pointvaluepair, toomanyiterationsexception, util

The LinearOptimizer.java Java example source code

/*
 * 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.linear;

import java.util.Collection;
import java.util.Collections;
import org.apache.commons.math3.exception.TooManyIterationsException;
import org.apache.commons.math3.optim.OptimizationData;
import org.apache.commons.math3.optim.PointValuePair;
import org.apache.commons.math3.optim.nonlinear.scalar.MultivariateOptimizer;

/**
 * Base class for implementing linear optimizers.
 *
 * @since 3.1
 */
public abstract class LinearOptimizer
    extends MultivariateOptimizer {
    /**
     * Linear objective function.
     */
    private LinearObjectiveFunction function;
    /**
     * Linear constraints.
     */
    private Collection<LinearConstraint> linearConstraints;
    /**
     * Whether to restrict the variables to non-negative values.
     */
    private boolean nonNegative;

    /**
     * Simple constructor with default settings.
     *
     */
    protected LinearOptimizer() {
        super(null); // No convergence checker.
    }

    /**
     * @return {@code true} if the variables are restricted to non-negative values.
     */
    protected boolean isRestrictedToNonNegative() {
        return nonNegative;
    }

    /**
     * @return the optimization type.
     */
    protected LinearObjectiveFunction getFunction() {
        return function;
    }

    /**
     * @return the optimization type.
     */
    protected Collection<LinearConstraint> getConstraints() {
        return Collections.unmodifiableCollection(linearConstraints);
    }

    /**
     * {@inheritDoc}
     *
     * @param optData Optimization data. In addition to those documented in
     * {@link MultivariateOptimizer#parseOptimizationData(OptimizationData[])
     * MultivariateOptimizer}, this method will register the following data:
     * <ul>
     *  <li>{@link LinearObjectiveFunction}
     *  <li>{@link LinearConstraintSet}
     *  <li>{@link NonNegativeConstraint}
     * </ul>
     * @return {@inheritDoc}
     * @throws TooManyIterationsException if the maximal number of
     * iterations is exceeded.
     */
    @Override
    public PointValuePair optimize(OptimizationData... optData)
        throws TooManyIterationsException {
        // Set up base class and perform computation.
        return super.optimize(optData);
    }

    /**
     * Scans the list of (required and optional) optimization data that
     * characterize the problem.
     *
     * @param optData Optimization data.
     * The following data will be looked for:
     * <ul>
     *  <li>{@link LinearObjectiveFunction}
     *  <li>{@link LinearConstraintSet}
     *  <li>{@link NonNegativeConstraint}
     * </ul>
     */
    @Override
    protected void parseOptimizationData(OptimizationData... optData) {
        // Allow base class to register its own data.
        super.parseOptimizationData(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 LinearObjectiveFunction) {
                function = (LinearObjectiveFunction) data;
                continue;
            }
            if (data instanceof LinearConstraintSet) {
                linearConstraints = ((LinearConstraintSet) data).getConstraints();
                continue;
            }
            if  (data instanceof NonNegativeConstraint) {
                nonNegative = ((NonNegativeConstraint) data).isRestrictedToNonNegative();
                continue;
            }
        }
    }
}

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