summaryrefslogtreecommitdiff
path: root/src/main/java/org/apache/commons/math3/ml/neuralnet/FeatureInitializerFactory.java
diff options
context:
space:
mode:
Diffstat (limited to 'src/main/java/org/apache/commons/math3/ml/neuralnet/FeatureInitializerFactory.java')
-rw-r--r--src/main/java/org/apache/commons/math3/ml/neuralnet/FeatureInitializerFactory.java114
1 files changed, 114 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/ml/neuralnet/FeatureInitializerFactory.java b/src/main/java/org/apache/commons/math3/ml/neuralnet/FeatureInitializerFactory.java
new file mode 100644
index 0000000..f5569b1
--- /dev/null
+++ b/src/main/java/org/apache/commons/math3/ml/neuralnet/FeatureInitializerFactory.java
@@ -0,0 +1,114 @@
+/*
+ * 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;
+
+import org.apache.commons.math3.distribution.RealDistribution;
+import org.apache.commons.math3.distribution.UniformRealDistribution;
+import org.apache.commons.math3.analysis.UnivariateFunction;
+import org.apache.commons.math3.analysis.function.Constant;
+import org.apache.commons.math3.random.RandomGenerator;
+
+/**
+ * Creates functions that will select the initial values of a neuron's
+ * features.
+ *
+ * @since 3.3
+ */
+public class FeatureInitializerFactory {
+ /** Class contains only static methods. */
+ private FeatureInitializerFactory() {}
+
+ /**
+ * Uniform sampling of the given range.
+ *
+ * @param min Lower bound of the range.
+ * @param max Upper bound of the range.
+ * @param rng Random number generator used to draw samples from a
+ * uniform distribution.
+ * @return an initializer such that the features will be initialized with
+ * values within the given range.
+ * @throws org.apache.commons.math3.exception.NumberIsTooLargeException
+ * if {@code min >= max}.
+ */
+ public static FeatureInitializer uniform(final RandomGenerator rng,
+ final double min,
+ final double max) {
+ return randomize(new UniformRealDistribution(rng, min, max),
+ function(new Constant(0), 0, 0));
+ }
+
+ /**
+ * Uniform sampling of the given range.
+ *
+ * @param min Lower bound of the range.
+ * @param max Upper bound of the range.
+ * @return an initializer such that the features will be initialized with
+ * values within the given range.
+ * @throws org.apache.commons.math3.exception.NumberIsTooLargeException
+ * if {@code min >= max}.
+ */
+ public static FeatureInitializer uniform(final double min,
+ final double max) {
+ return randomize(new UniformRealDistribution(min, max),
+ function(new Constant(0), 0, 0));
+ }
+
+ /**
+ * Creates an initializer from a univariate function {@code f(x)}.
+ * The argument {@code x} is set to {@code init} at the first call
+ * and will be incremented at each call.
+ *
+ * @param f Function.
+ * @param init Initial value.
+ * @param inc Increment
+ * @return the initializer.
+ */
+ public static FeatureInitializer function(final UnivariateFunction f,
+ final double init,
+ final double inc) {
+ return new FeatureInitializer() {
+ /** Argument. */
+ private double arg = init;
+
+ /** {@inheritDoc} */
+ public double value() {
+ final double result = f.value(arg);
+ arg += inc;
+ return result;
+ }
+ };
+ }
+
+ /**
+ * Adds some amount of random data to the given initializer.
+ *
+ * @param random Random variable distribution.
+ * @param orig Original initializer.
+ * @return an initializer whose {@link FeatureInitializer#value() value}
+ * method will return {@code orig.value() + random.sample()}.
+ */
+ public static FeatureInitializer randomize(final RealDistribution random,
+ final FeatureInitializer orig) {
+ return new FeatureInitializer() {
+ /** {@inheritDoc} */
+ public double value() {
+ return orig.value() + random.sample();
+ }
+ };
+ }
+}