VertexLabelDecoder.java

/*
 * Copyright © 2014 - 2021 Leipzig University (Database Research Group)
 *
 * Licensed 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.gradoop.flink.io.impl.tlf.functions;

import org.apache.flink.api.common.functions.RichMapFunction;
import org.apache.flink.configuration.Configuration;
import org.gradoop.common.model.impl.pojo.EPGMVertex;
import org.gradoop.flink.io.impl.tlf.TLFConstants;
import org.gradoop.flink.model.impl.layouts.transactional.tuples.GraphTransaction;

import java.util.HashMap;
import java.util.Map;

/**
 * Maps the vertex dictionary to a given graph transaction. The
 * integer-like labels are replaced by those from the dictionary files
 * where the integer value from the old labels matches the corresponding
 * keys from the dictionary.
 */
public class VertexLabelDecoder extends
  RichMapFunction<GraphTransaction, GraphTransaction> {

  /**
   * Map which contains a vertex dictionary.
   */
  private Map<Integer, String> vertexDictionary;

  @Override
  public void open(Configuration parameters) throws Exception {
    super.open(parameters);
    vertexDictionary = getRuntimeContext()
      .<HashMap<Integer, String>>getBroadcastVariable(TLFConstants.VERTEX_DICTIONARY)
      .get(0);
  }

  @Override
  public GraphTransaction map(GraphTransaction graphTransaction)
      throws Exception {
    String label;
    for (EPGMVertex vertex : graphTransaction.getVertices()) {
      label = vertexDictionary.get(Integer.parseInt(vertex.getLabel()));
      if (label != null) {
        vertex.setLabel(label);
      } else {
        vertex.setLabel(vertex.getLabel() + TLFConstants.EMPTY_LABEL);
      }
    }
    return graphTransaction;
  }
}