juneau-core/juneau-marshall/src/main/java/org/apache/juneau/utils/WeightedAverage.java

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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
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// ***************************************************************************************************************************
package org.apache.juneau.utils;

/**
 * A simple weighted average of numbers.
 */
public class WeightedAverage {
	private Double value = 0d;
	private int weight = 0;

	/**
	 * Add a number with a weight to this average.
	 *
	 * @param w The weight of the new value.
	 * @param v The new value.
	 * @return This object (for method chaining).
	 */
	public WeightedAverage add(int w, Number v) {
		if (v != null) {
			try {
				double w1 = weight, w2 = w;
				weight = Math.addExact(weight, w);
				if (weight != 0) {
					value = (value * (w1/weight)) + (v.floatValue() * (w2/weight));
				}
			} catch (ArithmeticException ae) {
				throw new ArithmeticException("Weight overflow.");
			}
		}
		return this;
	}

	/**
	 * Returns the weighted average of all numbers.
	 *
	 * @return The weighted average of all numbers.
	 */
	public double getValue() {
		return value;
	}
}