diff --git a/osu.Game/Screens/Ranking/Statistics/UnstableRate.cs b/osu.Game/Screens/Ranking/Statistics/UnstableRate.cs new file mode 100644 index 0000000000..5b368c3e8d --- /dev/null +++ b/osu.Game/Screens/Ranking/Statistics/UnstableRate.cs @@ -0,0 +1,39 @@ +// Copyright (c) ppy Pty Ltd . Licensed under the MIT Licence. +// See the LICENCE file in the repository root for full licence text. + +using System; +using System.Collections.Generic; +using System.Linq; +using osu.Game.Rulesets.Scoring; + +namespace osu.Game.Screens.Ranking.Statistics +{ + /// + /// Displays the unstable rate statistic for a given play. + /// + public class UnstableRate : SimpleStatisticItem + { + /// + /// Creates and computes an statistic. + /// + /// Sequence of s to calculate the unstable rate based on. + public UnstableRate(IEnumerable hitEvents) + : base("Unstable Rate") + { + var timeOffsets = hitEvents.Select(ev => ev.TimeOffset).ToArray(); + Value = 10 * standardDeviation(timeOffsets); + } + + private static double standardDeviation(double[] timeOffsets) + { + if (timeOffsets.Length == 0) + return double.NaN; + + var mean = timeOffsets.Average(); + var squares = timeOffsets.Select(offset => Math.Pow(offset - mean, 2)).Sum(); + return Math.Sqrt(squares / timeOffsets.Length); + } + + protected override string DisplayValue(double value) => double.IsNaN(value) ? "(not available)" : value.ToString("N2"); + } +}