opennlp.tools.util.Sequence.java Source code

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Here is the source code for opennlp.tools.util.Sequence.java

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/*
 * 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 opennlp.tools.util;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Objects;

/** Represents a weighted sequence of outcomes. */
public class Sequence implements Comparable<Sequence> {
    private double score;
    private List<String> outcomes;
    private List<Double> probs;
    private static final Double ONE = 1.0d;

    /** Creates a new sequence of outcomes. */
    public Sequence() {
        outcomes = new ArrayList<>(1);
        probs = new ArrayList<>(1);
        score = 0d;
    }

    public Sequence(Sequence s) {
        outcomes = new ArrayList<>(s.outcomes.size() + 1);
        outcomes.addAll(s.outcomes);
        probs = new ArrayList<>(s.probs.size() + 1);
        probs.addAll(s.probs);
        score = s.score;
    }

    public Sequence(Sequence s, String outcome, double p) {
        outcomes = new ArrayList<>(s.outcomes.size() + 1);
        outcomes.addAll(s.outcomes);
        outcomes.add(outcome);
        probs = new ArrayList<>(s.probs.size() + 1);
        probs.addAll(s.probs);
        probs.add(p);
        score = s.score + Math.log(p);
    }

    public Sequence(List<String> outcomes) {
        this.outcomes = outcomes;
        this.probs = Collections.nCopies(outcomes.size(), ONE);
    }

    public int compareTo(Sequence s) {
        return Double.compare(s.score, score);
    }

    @Override
    public int hashCode() {
        return Objects.hash(outcomes, probs, score);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;

        if (obj instanceof Sequence) {
            Sequence other = (Sequence) obj;
            double epsilon = 0.0000001;
            return Objects.equals(outcomes, other.outcomes) && Objects.equals(probs, other.probs)
                    && Math.abs(score - other.score) < epsilon;
        }

        return false;
    }

    /** Adds an outcome and probability to this sequence.
       * @param outcome the outcome to be added.
       * @param p the probability associated with this outcome.
       */
    public void add(String outcome, double p) {
        outcomes.add(outcome);
        probs.add(p);
        score += Math.log(p);
    }

    /** Returns a list of outcomes for this sequence.
     * @return a list of outcomes.
     */
    public List<String> getOutcomes() {
        return outcomes;
    }

    /** Returns an array of probabilities associated with the outcomes of this sequence.
     * @return an array of probabilities.
     */
    public double[] getProbs() {
        double[] ps = new double[probs.size()];
        getProbs(ps);
        return ps;
    }

    /**
     * Returns the score of this sequence.
     * @return The score of this sequence.
     */
    public double getScore() {
        return score;
    }

    /** Populates  an array with the probabilities associated with the outcomes of this sequence.
     * @param ps a pre-allocated array to use to hold the values of the
     *           probabilities of the outcomes for this sequence.
     */
    public void getProbs(double[] ps) {
        for (int pi = 0, pl = probs.size(); pi < pl; pi++) {
            ps[pi] = probs.get(pi);
        }
    }

    @Override
    public String toString() {
        return score + " " + outcomes;
    }
}