001/*
002 * Java Genetic Algorithm Library (jenetics-7.0.0).
003 * Copyright (c) 2007-2022 Franz Wilhelmstötter
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 *
017 * Author:
018 *    Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
019 */
020package io.jenetics.prog.regression;
021
022import static java.util.Objects.requireNonNull;
023
024import io.jenetics.ext.util.Tree;
025
026import io.jenetics.prog.op.Op;
027
028/**
029 * This interface represents a set of sample points, which can be evaluated with
030 * a given evolved <em>program</em>.
031 *
032 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
033 * @version 6.0
034 * @since 6.0
035 */
036@FunctionalInterface
037public interface Sampling<T> {
038
039        /**
040         * This class represents the result of a sample calculation, which contains
041         * the array of calculated values and a corresponding array with expected
042         * sample values. This two arrays can then be used for calculating the
043         * error between modeled regression function and actual sample values.
044         *
045         * @param <T> the sample result  type
046         */
047        record Result<T>(T[] calculated, T[] expected) {
048                /**
049                 * @param calculated the calculated result values
050                 * @param expected the expected sample result values
051                 * @throws NullPointerException if one of the arguments is {@code null}
052                 */
053                public Result {
054                        calculated = calculated.clone();
055                        expected = expected.clone();
056                }
057        }
058
059        /**
060         * Evaluates the given {@code program} tree with its sample points. The
061         * returned result object may be {@code null} if no sample point has been
062         * added to the <em>sampling</em> when calling the {@code eval} method.
063         *
064         * @param program the program to evaluate
065         * @return the evaluated sample result. May be {@code null} if the sampling
066         *         is empty and contains no sample points.
067         */
068        Result<T> eval(final Tree<? extends Op<T>, ?> program);
069
070}