CountGraphHeads.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.distinction.functions;
- import org.apache.flink.api.java.tuple.Tuple2;
- import org.apache.flink.util.Collector;
- import org.gradoop.common.model.api.entities.GraphHead;
- import org.gradoop.flink.model.api.functions.GraphHeadReduceFunction;
- import java.util.Iterator;
- /**
- * Distinction function that just selects the first graph head of an isomorphic group.
- *
- * @param <G> graph head type
- */
- public class CountGraphHeads<G extends GraphHead> implements GraphHeadReduceFunction<G> {
- /**
- * property key to store graph count.
- */
- private final String propertyKey;
- /**
- * Constructor.
- *
- * @param propertyKey property key to store graph count.
- */
- public CountGraphHeads(String propertyKey) {
- this.propertyKey = propertyKey;
- }
- @Override
- public void reduce(Iterable<Tuple2<String, G>> iterable,
- Collector<G> collector) throws Exception {
- Iterator<Tuple2<String, G>> iterator = iterable.iterator();
- G graphHead = iterator.next().f1;
- int count = 1;
- while (iterator.hasNext()) {
- iterator.next();
- count++;
- }
- graphHead.setProperty(propertyKey, count);
- collector.collect(graphHead);
- }
- }