text: /*******************************************************************************
   * Copyright (c) 2015-2018 Skymind, Inc.
   *
   * This program and the accompanying materials are made available under the
   * terms of the Apache License, Version 2.0 which is available at
   * https://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.
   *
   * SPDX-License-Identifier: Apache-2.0
   ******************************************************************************/
  
  package org.deeplearning4j.iterator.provider;
  
  import lombok.NonNull;
  import org.deeplearning4j.iterator.LabeledSentenceProvider;
  import org.nd4j.common.base.Preconditions;
  import org.nd4j.common.primitives.Pair;
  import org.nd4j.common.util.MathUtils;
  
  import java.util.*;
  
  /**
   * Iterate over a set of sentences/documents,
   * where the sentences and labels are provided in lists.
   *
   * @author Alex Black
   */
  public class CollectionLabeledSentenceProvider implements LabeledSentenceProvider {
  
      private final List<String> sentences;
      private final List<String> labels;
      private final Random rng;
      private final int[] order;
      private final List<String> allLabels;
  
      private int cursor = 0;
  
      public CollectionLabeledSentenceProvider(@NonNull List<String> sentences,
                                               @NonNull List<String> labelsForSentences) {
          this(sentences, labelsForSentences, new Random());
      }
  
      public CollectionLabeledSentenceProvider(@NonNull List<String> sentences, @NonNull List<String> labelsForSentences,
                                               Random rng) {
          if (sentences.size() != labelsForSentences.size()) {
              throw new IllegalArgumentException("Sentences and labels must be same size (sentences size: "
                      + sentences.size() + ", labels size: " + labelsForSentences.size() + ")");
          }
  
          this.sentences = sentences;
          this.labels = labelsForSentences;
          this.rng = rng;
          if (rng == null) {
              order = null;
          } else {
              order = new int[sentences.size()];
              for (int i = 0; i < sentences.size(); i++) {
                  order[i] = i;
              }
  
              MathUtils.shuffleArray(order, rng);
          }
  
          //Collect set of unique labels for all sentences
          Set<String> uniqueLabels = new HashSet<>(labelsForSentences);
          allLabels = new ArrayList<>(uniqueLabels);
          Collections.sort(allLabels);
      }
  
      @Override
      public boolean hasNext() {
          return cursor < sentences.size();
      }
  
      @Override
      public Pair<String, String> nextSentence() {
          Preconditions.checkState(hasNext(), "No next element available");
          int idx;
          if (rng == null) {
              idx = cursor++;
          } else {
              idx = order[cursor++];
          }
          return new Pair<>(sentences.get(idx), labels.get(idx));
      }
  
      @Override
      public void reset() {
          cursor = 0;
          if (rng != null) {
              MathUtils.shuffleArray(order, rng);
          }
      }
  
      @Override
      public int totalNumSentences() {
          return sentences.size();
      }
  
      @Override
      public List<String> allLabels() {
          return allLabels;
      }
  
      @Override
      public int numLabelClasses() {
          return allLabels.size();
      }
  }
  