DistinctTargetIdsByEdgeLabel.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.model.impl.operators.statistics;

import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.tuple.Tuple1;
import org.gradoop.flink.model.impl.epgm.LogicalGraph;
import org.gradoop.flink.model.api.operators.UnaryGraphToValueOperator;
import org.gradoop.flink.model.impl.functions.tuple.Tuple2ToWithCount;
import org.gradoop.flink.model.impl.operators.count.functions.Tuple2FromTupleWithObjectAnd1L;
import org.gradoop.flink.model.impl.operators.statistics.functions.ToTargetIdWithLabel;
import org.gradoop.flink.model.impl.tuples.WithCount;

/**
 * Computes the number of distinct source ids per edge label.
 */
public class DistinctTargetIdsByEdgeLabel
  implements UnaryGraphToValueOperator<DataSet<WithCount<String>>> {

  @Override
  public DataSet<WithCount<String>> execute(LogicalGraph graph) {
    return graph.getEdges()
      .map(new ToTargetIdWithLabel<>())
      .groupBy(0, 1)
      .first(1)
      .<Tuple1<String>>project(1)
      .map(new Tuple2FromTupleWithObjectAnd1L<>())
      .groupBy(0)
      .sum(1)
      .map(new Tuple2ToWithCount<>());
  }
}