| /* |
| * Copyright (C) 2019, Matthias Sohn <matthias.sohn@sap.com> and others |
| * |
| * This program and the accompanying materials are made available under the |
| * terms of the Eclipse Distribution License v. 1.0 which is available at |
| * https://www.eclipse.org/org/documents/edl-v10.php. |
| * |
| * SPDX-License-Identifier: BSD-3-Clause |
| */ |
| package org.eclipse.jgit.util; |
| |
| /** |
| * Simple double statistics, computed incrementally, variance and standard |
| * deviation using Welford's online algorithm, see |
| * https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Welford's_online_algorithm |
| * |
| * @since 5.1.9 |
| */ |
| public class Stats { |
| private int n = 0; |
| |
| private double avg = 0.0; |
| |
| private double min = 0.0; |
| |
| private double max = 0.0; |
| |
| private double sum = 0.0; |
| |
| /** |
| * Add a value |
| * |
| * @param x |
| * value |
| */ |
| public void add(double x) { |
| n++; |
| min = n == 1 ? x : Math.min(min, x); |
| max = n == 1 ? x : Math.max(max, x); |
| double d = x - avg; |
| avg += d / n; |
| sum += d * d * (n - 1) / n; |
| } |
| |
| /** |
| * @return number of the added values |
| */ |
| public int count() { |
| return n; |
| } |
| |
| /** |
| * @return minimum of the added values |
| */ |
| public double min() { |
| if (n < 1) { |
| return Double.NaN; |
| } |
| return min; |
| } |
| |
| /** |
| * @return maximum of the added values |
| */ |
| public double max() { |
| if (n < 1) { |
| return Double.NaN; |
| } |
| return max; |
| } |
| |
| /** |
| * @return average of the added values |
| */ |
| |
| public double avg() { |
| if (n < 1) { |
| return Double.NaN; |
| } |
| return avg; |
| } |
| |
| /** |
| * @return variance of the added values |
| */ |
| public double var() { |
| if (n < 2) { |
| return Double.NaN; |
| } |
| return sum / (n - 1); |
| } |
| |
| /** |
| * @return standard deviation of the added values |
| */ |
| public double stddev() { |
| return Math.sqrt(this.var()); |
| } |
| } |