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osu-lazer/osu.Game/Rulesets/Scoring/HitEventExtensions.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;
namespace osu.Game.Rulesets.Scoring
{
public static class HitEventExtensions
{
/// <summary>
/// Calculates the "unstable rate" for a sequence of <see cref="HitEvent"/>s.
/// </summary>
/// <returns>
/// A non-null <see langword="double"/> value if unstable rate could be calculated,
/// and <see langword="null"/> if unstable rate cannot be calculated due to <paramref name="hitEvents"/> being empty.
/// </returns>
public static double? CalculateUnstableRate(this IEnumerable<HitEvent> hitEvents)
{
double[] timeOffsets = hitEvents.Where(affectsUnstableRate).Select(ev => ev.TimeOffset).ToArray();
return 10 * standardDeviation(timeOffsets);
}
2022-02-28 18:14:43 +08:00
/// <summary>
/// Calculates the average hit offset/error for a sequence of <see cref="HitEvent"/>s, where negative numbers mean the user hit too early on average.
/// </summary>
/// <returns>
/// A non-null <see langword="double"/> value if unstable rate could be calculated,
/// and <see langword="null"/> if unstable rate cannot be calculated due to <paramref name="hitEvents"/> being empty.
/// </returns>
public static double? CalculateAverageHitError(this IEnumerable<HitEvent> hitEvents)
{
double[] timeOffsets = hitEvents.Where(affectsUnstableRate).Select(ev => ev.TimeOffset).ToArray();
if (timeOffsets.Length == 0)
return null;
return timeOffsets.Average();
}
private static bool affectsUnstableRate(HitEvent e) => !(e.HitObject.HitWindows is HitWindows.EmptyHitWindows) && e.Result.IsHit();
private static double? standardDeviation(double[] timeOffsets)
{
if (timeOffsets.Length == 0)
return null;
double mean = timeOffsets.Average();
double squares = timeOffsets.Select(offset => Math.Pow(offset - mean, 2)).Sum();
return Math.Sqrt(squares / timeOffsets.Length);
}
}
}