| /* |
| * 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.math4.ml.neuralnet; |
| |
| import java.util.List; |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.Comparator; |
| |
| import org.apache.commons.math4.exception.NotStrictlyPositiveException; |
| import org.apache.commons.math4.ml.distance.DistanceMeasure; |
| |
| /** |
| * Utility for ranking the units (neurons) of a network. |
| * |
| * @since 4.0 |
| */ |
| public class MapRanking { |
| /** List corresponding to the map passed to the constructor. */ |
| private final List<Neuron> map = new ArrayList<>(); |
| /** Distance function for sorting. */ |
| private final DistanceMeasure distance; |
| |
| /** |
| * @param neurons List to be ranked. |
| * No defensive copy is performed. |
| * The {@link #rank(double[],int) created list of units} will |
| * be sorted in increasing order of the {@code distance}. |
| * @param distance Distance function. |
| */ |
| public MapRanking(Iterable<Neuron> neurons, |
| DistanceMeasure distance) { |
| this.distance = distance; |
| |
| for (Neuron n : neurons) { |
| map.add(n); // No defensive copy. |
| } |
| } |
| |
| /** |
| * Creates a list of the neurons whose features best correspond to the |
| * given {@code features}. |
| * |
| * @param features Data. |
| * @return the list of neurons sorted in decreasing order of distance to |
| * the given data. |
| * @throws org.apache.commons.math4.exception.DimensionMismatchException |
| * if the size of the input is not compatible with the neurons features |
| * size. |
| */ |
| public List<Neuron> rank(double[] features) { |
| return rank(features, map.size()); |
| } |
| |
| /** |
| * Creates a list of the neurons whose features best correspond to the |
| * given {@code features}. |
| * |
| * @param features Data. |
| * @param max Maximum size of the returned list. |
| * @return the list of neurons sorted in decreasing order of distance to |
| * the given data. |
| * @throws org.apache.commons.math4.exception.DimensionMismatchException |
| * if the size of the input is not compatible with the neurons features |
| * size. |
| * @throws NotStrictlyPositiveException if {@code max <= 0}. |
| */ |
| public List<Neuron> rank(double[] features, |
| int max) { |
| if (max <= 0) { |
| throw new NotStrictlyPositiveException(max); |
| } |
| final int m = max <= map.size() ? |
| max : |
| map.size(); |
| final List<PairNeuronDouble> list = new ArrayList<>(m); |
| |
| for (final Neuron n : map) { |
| final double d = distance.compute(n.getFeatures(), features); |
| final PairNeuronDouble p = new PairNeuronDouble(n, d); |
| |
| if (list.size() < m) { |
| list.add(p); |
| if (list.size() > 1) { |
| // Sort if there is more than 1 element. |
| Collections.sort(list, PairNeuronDouble.COMPARATOR); |
| } |
| } else { |
| final int last = list.size() - 1; |
| if (PairNeuronDouble.COMPARATOR.compare(p, list.get(last)) < 0) { |
| list.set(last, p); // Replace worst entry. |
| if (last > 0) { |
| // Sort if there is more than 1 element. |
| Collections.sort(list, PairNeuronDouble.COMPARATOR); |
| } |
| } |
| } |
| } |
| |
| final List<Neuron> result = new ArrayList<>(m); |
| for (PairNeuronDouble p : list) { |
| result.add(p.getNeuron()); |
| } |
| |
| return result; |
| } |
| |
| /** |
| * Helper data structure holding a (Neuron, double) pair. |
| */ |
| private static class PairNeuronDouble { |
| /** Comparator. */ |
| static final Comparator<PairNeuronDouble> COMPARATOR |
| = new Comparator<PairNeuronDouble>() { |
| /** {@inheritDoc} */ |
| @Override |
| public int compare(PairNeuronDouble o1, |
| PairNeuronDouble o2) { |
| return Double.compare(o1.value, o2.value); |
| } |
| }; |
| /** Key. */ |
| private final Neuron neuron; |
| /** Value. */ |
| private final double value; |
| |
| /** |
| * @param neuron Neuron. |
| * @param value Value. |
| */ |
| PairNeuronDouble(Neuron neuron, double value) { |
| this.neuron = neuron; |
| this.value = value; |
| } |
| |
| /** @return the neuron. */ |
| public Neuron getNeuron() { |
| return neuron; |
| } |
| } |
| } |