01 /*
02 * Java Genetic Algorithm Library (jenetics-6.1.0).
03 * Copyright (c) 2007-2020 Franz Wilhelmstötter
04 *
05 * Licensed under the Apache License, Version 2.0 (the "License");
06 * you may not use this file except in compliance with the License.
07 * You may obtain a copy of the License at
08 *
09 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 * Author:
18 * Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
19 */
20 package io.jenetics.prog.regression;
21
22 import static java.util.Objects.requireNonNull;
23
24 import io.jenetics.ext.util.Tree;
25
26 import io.jenetics.prog.op.Op;
27
28 /**
29 * This interface represents a set of sample points, which can be evaluated with
30 * a given evolved <em>program</em>.
31 *
32 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
33 * @version 6.0
34 * @since 6.0
35 */
36 @FunctionalInterface
37 public interface Sampling<T> {
38
39 /**
40 * This class represents the result of a sample calculation, which contains
41 * the array of calculated values and a corresponding array with expected
42 * sample values. This two arrays can then be used for calculating the
43 * error between modeled regression function and actual sample values.
44 *
45 * @param <T> the sample result type
46 */
47 final class Result<T> {
48 private final T[] _calculated;
49 private final T[] _expected;
50
51 private Result(final T[] calculated, final T[] expected) {
52 _calculated = requireNonNull(calculated);
53 _expected = requireNonNull(expected);
54 }
55
56 /**
57 * Return the the calculated result values.
58 *
59 * @return the the calculated result values
60 */
61 public T[] calculated() {
62 return _calculated;
63 }
64
65 /**
66 * Return the expected sample result values.
67 *
68 * @return the expected sample result values
69 */
70 public T[] expected() {
71 return _expected;
72 }
73
74 /**
75 * Create a new sampling result object.
76 *
77 * @param calculated the calculated values
78 * @param expected the expected sample values
79 * @param <T> the sample type
80 * @return a new sampling result object
81 * @throws NullPointerException if one of the arguments is {@code null}
82 */
83 public static <T> Result<T> of(final T[] calculated, final T[] expected) {
84 return new Result<>(calculated.clone(), expected.clone());
85 }
86 }
87
88 /**
89 * Evaluates the given {@code program} tree with its sample points. The
90 * returned result object may be {@code null} if no sample point has been
91 * added to the <em>sampling</em> when calling the {@code eval} method.
92 *
93 * @param program the program to evaluate
94 * @return the evaluated sample result. May be {@code null} if the sampling
95 * is empty and contains no sample points.
96 */
97 Result<T> eval(final Tree<? extends Op<T>, ?> program);
98
99 }
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