| /* |
| * Copyright (C) 2019, Matthias Sohn <matthias.sohn@sap.com> |
| * and other copyright owners as documented in the project's IP log. |
| * |
| * This program and the accompanying materials are made available |
| * under the terms of the Eclipse Distribution License v1.0 which |
| * accompanies this distribution, is reproduced below, and is |
| * available at http://www.eclipse.org/org/documents/edl-v10.php |
| * |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or |
| * without modification, are permitted provided that the following |
| * conditions are met: |
| * |
| * - Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * - Redistributions in binary form must reproduce the above |
| * copyright notice, this list of conditions and the following |
| * disclaimer in the documentation and/or other materials provided |
| * with the distribution. |
| * |
| * - Neither the name of the Eclipse Foundation, Inc. nor the |
| * names of its contributors may be used to endorse or promote |
| * products derived from this software without specific prior |
| * written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND |
| * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, |
| * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR |
| * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; |
| * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER |
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, |
| * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
| * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| 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()); |
| } |
| } |