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osu-lazer/osu.Game/Screens/Ranking/Statistics/UnstableRate.cs

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// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. 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
{
/// <summary>
/// Displays the unstable rate statistic for a given play.
/// </summary>
public class UnstableRate : SimpleStatisticItem<double>
{
/// <summary>
/// Creates and computes an <see cref="UnstableRate"/> statistic.
/// </summary>
/// <param name="hitEvents">Sequence of <see cref="HitEvent"/>s to calculate the unstable rate based on.</param>
public UnstableRate(IEnumerable<HitEvent> hitEvents)
: base("Unstable Rate")
{
var timeOffsets = hitEvents.Where(e => !(e.HitObject.HitWindows is HitWindows.EmptyHitWindows) && e.Result.IsHit())
.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");
}
}