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Diffstat (limited to 'src/main/java/org/apache/commons/math3/ml/neuralnet/sofm/LearningFactorFunctionFactory.java')
-rw-r--r-- | src/main/java/org/apache/commons/math3/ml/neuralnet/sofm/LearningFactorFunctionFactory.java | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/ml/neuralnet/sofm/LearningFactorFunctionFactory.java b/src/main/java/org/apache/commons/math3/ml/neuralnet/sofm/LearningFactorFunctionFactory.java new file mode 100644 index 0000000..9165e82 --- /dev/null +++ b/src/main/java/org/apache/commons/math3/ml/neuralnet/sofm/LearningFactorFunctionFactory.java @@ -0,0 +1,117 @@ +/* + * 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.ml.neuralnet.sofm; + +import org.apache.commons.math3.ml.neuralnet.sofm.util.ExponentialDecayFunction; +import org.apache.commons.math3.ml.neuralnet.sofm.util.QuasiSigmoidDecayFunction; +import org.apache.commons.math3.exception.OutOfRangeException; + +/** + * Factory for creating instances of {@link LearningFactorFunction}. + * + * @since 3.3 + */ +public class LearningFactorFunctionFactory { + /** Class contains only static methods. */ + private LearningFactorFunctionFactory() {} + + /** + * Creates an exponential decay {@link LearningFactorFunction function}. + * It will compute <code>a e<sup>-x / b</sup></code>, + * where {@code x} is the (integer) independent variable and + * <ul> + * <li><code>a = initValue</code> + * <li><code>b = -numCall / ln(valueAtNumCall / initValue)</code> + * </ul> + * + * @param initValue Initial value, i.e. + * {@link LearningFactorFunction#value(long) value(0)}. + * @param valueAtNumCall Value of the function at {@code numCall}. + * @param numCall Argument for which the function returns + * {@code valueAtNumCall}. + * @return the learning factor function. + * @throws org.apache.commons.math3.exception.OutOfRangeException + * if {@code initValue <= 0} or {@code initValue > 1}. + * @throws org.apache.commons.math3.exception.NotStrictlyPositiveException + * if {@code valueAtNumCall <= 0}. + * @throws org.apache.commons.math3.exception.NumberIsTooLargeException + * if {@code valueAtNumCall >= initValue}. + * @throws org.apache.commons.math3.exception.NotStrictlyPositiveException + * if {@code numCall <= 0}. + */ + public static LearningFactorFunction exponentialDecay(final double initValue, + final double valueAtNumCall, + final long numCall) { + if (initValue <= 0 || + initValue > 1) { + throw new OutOfRangeException(initValue, 0, 1); + } + + return new LearningFactorFunction() { + /** DecayFunction. */ + private final ExponentialDecayFunction decay + = new ExponentialDecayFunction(initValue, valueAtNumCall, numCall); + + /** {@inheritDoc} */ + public double value(long n) { + return decay.value(n); + } + }; + } + + /** + * Creates an sigmoid-like {@code LearningFactorFunction function}. + * The function {@code f} will have the following properties: + * <ul> + * <li>{@code f(0) = initValue}</li> + * <li>{@code numCall} is the inflexion point</li> + * <li>{@code slope = f'(numCall)}</li> + * </ul> + * + * @param initValue Initial value, i.e. + * {@link LearningFactorFunction#value(long) value(0)}. + * @param slope Value of the function derivative at {@code numCall}. + * @param numCall Inflexion point. + * @return the learning factor function. + * @throws org.apache.commons.math3.exception.OutOfRangeException + * if {@code initValue <= 0} or {@code initValue > 1}. + * @throws org.apache.commons.math3.exception.NumberIsTooLargeException + * if {@code slope >= 0}. + * @throws org.apache.commons.math3.exception.NotStrictlyPositiveException + * if {@code numCall <= 0}. + */ + public static LearningFactorFunction quasiSigmoidDecay(final double initValue, + final double slope, + final long numCall) { + if (initValue <= 0 || + initValue > 1) { + throw new OutOfRangeException(initValue, 0, 1); + } + + return new LearningFactorFunction() { + /** DecayFunction. */ + private final QuasiSigmoidDecayFunction decay + = new QuasiSigmoidDecayFunction(initValue, slope, numCall); + + /** {@inheritDoc} */ + public double value(long n) { + return decay.value(n); + } + }; + } +} |