/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.flink.streaming.api.functions.windowing.delta;
import org.apache.flink.annotation.PublicEvolving;
import org.apache.flink.streaming.api.functions.windowing.delta.extractor.Extractor;
/**
* This delta function calculates the euclidean distance between two given
* points.
*
* <p>Euclidean distance: http://en.wikipedia.org/wiki/Euclidean_distance
*
* @param <DATA>
* The input data type. This delta function works with a double[],
* but can extract/convert to it from any other given object in case
* the respective extractor has been set. See
* {@link ExtractionAwareDeltaFunction} for more information.
*/
@PublicEvolving
public class EuclideanDistance<DATA> extends ExtractionAwareDeltaFunction<DATA, double[]> {
public EuclideanDistance() {
super(null);
}
public EuclideanDistance(Extractor<DATA, double[]> converter) {
super(converter);
}
private static final long serialVersionUID = 3119432599634512359L;
@Override
public double getNestedDelta(double[] oldDataPoint, double[] newDataPoint) {
double result = 0;
for (int i = 0; i < oldDataPoint.length; i++) {
result += (oldDataPoint[i] - newDataPoint[i]) * (oldDataPoint[i] - newDataPoint[i]);
}
return Math.sqrt(result);
}
}