001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.commons.lang;
018
019import static org.apache.juneau.commons.utils.Shorts.*;
020
021/**
022 * A simple weighted average of numbers.
023 *
024 */
025public class WeightedAverage {
026   private Double value = 0d;
027   private int weight;
028
029   /**
030    * Add a number with a weight to this average.
031    *
032    * @param w The weight of the new value.
033    * @param v The new value.  Can be <jk>null</jk>, in which case this call is a no-op.
034    * @return This object.
035    */
036   public WeightedAverage add(int w, Number v) {
037      if (nn(v)) {
038         double w1 = weight;
039         double w2 = w;
040         weight = Math.addExact(weight, w);
041         if (weight != 0) {
042            value = (value * (w1 / weight)) + (v.floatValue() * (w2 / weight));
043         }
044      }
045      return this;
046   }
047
048   /**
049    * Returns the weighted average of all numbers.
050    *
051    * @return The weighted average of all numbers.
052    */
053   public double getValue() { return value; }
054}