CentroidAverager.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.kmeans.functions;

import org.apache.flink.api.common.functions.MapFunction;
import org.apache.flink.api.java.tuple.Tuple3;
import org.gradoop.flink.model.impl.operators.kmeans.util.Centroid;
import org.gradoop.flink.model.impl.operators.kmeans.util.Point;

/**
 * Computes the average value of the points coordinates assigned to the same centroid.
 */
public class CentroidAverager implements MapFunction<Tuple3<Integer, Point, Long>, Centroid> {

  /**
   * Creates a new centroid, which coordinates are the average coordinates of the points assigned to the
   * same centroid.
   *
   * @param value Tuple containing the centroidId, its summed up points and the amount of points that
   *              were summed up
   * @return Returns the new Centroid, taking the average coordinates of the assigned points
   */
  @Override
  public Centroid map(Tuple3<Integer, Point, Long> value) {
    return new Centroid(value.f0, value.f1.div(value.f2));
  }
}