001/*
002 * Java Genetic Algorithm Library (jenetics-7.2.0).
003 * Copyright (c) 2007-2023 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 java.util.List;
023import java.util.function.Function;
024
025import io.jenetics.ext.util.Tree;
026
027import io.jenetics.prog.op.Op;
028
029/**
030 * This interface represents a set of sample points, which can be evaluated with
031 * a given evolved <em>program</em>.
032 *
033 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
034 * @version 7.1
035 * @since 6.0
036 */
037@FunctionalInterface
038public interface Sampling<T> {
039
040        /**
041         * This class represents the result of a sample calculation, which contains
042         * the array of calculated values and a corresponding array with expected
043         * sample values. This two arrays can then be used for calculating the
044         * error between modeled regression function and actual sample values.
045         *
046         * @param <T> the sample result type
047         */
048        record Result<T>(T[] calculated, T[] expected) {
049                /**
050                 * @param calculated the calculated result values
051                 * @param expected the expected sample result values
052                 * @throws NullPointerException if one of the arguments is {@code null}
053                 */
054                public Result {
055                        calculated = calculated.clone();
056                        expected = expected.clone();
057                }
058        }
059
060        /**
061         * Evaluates the given {@code program} tree with its sample points. The
062         * returned result object may be {@code null} if no sample point has been
063         * added to the <em>sampling</em> when calling the {@code eval} method.
064         *
065         * @param program the program to evaluate
066         * @return the evaluated sample result. May be {@code null} if the sampling
067         *         is empty and contains no sample points.
068         */
069        //@Deprecated(since = "7.1", forRemoval = true)
070        Result<T> eval(final Tree<? extends Op<T>, ?> program);
071
072        /**
073         * Evaluates the given {@code function} tree with its sample points. The
074         * returned result object may be {@code null} if no sample point has been
075         * added to the <em>sampling</em> when calling the {@code eval} method.
076         *
077         * @param function the function to evaluate
078         * @return the evaluated sample result. May be {@code null} if the sampling
079         *         is empty and contains no sample points.
080         */
081        default Result<T> eval(final Function<? super T[], ? extends T> function) {
082                throw new UnsupportedOperationException();
083        }
084
085        /**
086         * Create a new sampling object from the given sample points.
087         *
088         * @since 7.1
089         *
090         * @param samples the sample points
091         * @param <T> the sample type
092         * @return a new sampling object
093         */
094        static <T> Sampling<T> of(final List<? extends Sample<? extends T>> samples) {
095                return new SampleList<>(samples);
096        }
097
098        /**
099         * Create a new sampling object from the given sample points.
100         *
101         * @since 7.1
102         *
103         * @param samples the sample points
104         * @param <T> the sample type
105         * @return a new sampling object
106         */
107        @SafeVarargs
108        static <T> Sampling<T> of(final Sample<? extends T>... samples) {
109                return Sampling.of(List.of(samples));
110        }
111
112}