70 lines
3.1 KiB
C#
70 lines
3.1 KiB
C#
using System;
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namespace DTS.Common.Calculations
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{
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public class HeadInjuryCriterion
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{
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/// <summary>
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/// Calculates the head injury criterion given a resultant channel, and a desired clip length
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/// </summary>
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/// <param name="resultant">Acceleration vector (x,y,z resultant)</param>
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/// <param name="SPS">Actual sample rate</param>
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/// <param name="clipLengthMS">Length in ms </param>
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/// <returns>MAX Head Injury Criterion over the data input for the clip requested</returns>
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public static HICResult GetHeadInjuryCriterion(ChannelData resultant, double SPS, int clipLengthMS)
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{
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System.Diagnostics.Trace.Assert(SPS > 0, "Actual sample rate must be positive");
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System.Diagnostics.Trace.Assert(clipLengthMS > 0, "Clip length must be positive");
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int maxHICPoint = int.MinValue;
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double maxHIC = int.MinValue;
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int maxHICEndPoint = int.MinValue;
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int maxclip = Convert.ToInt32(Math.Ceiling(clipLengthMS * SPS / 1000D));
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for (int clip = 1; clip <= maxclip; clip++)
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{
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System.Diagnostics.Trace.Assert(clip < resultant.FilteredEU.Length, string.Format("data must be atleast {0} ms", clipLengthMS));
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double clipInSeconds = clip / SPS;
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for (int i = 0; i < resultant.FilteredEU.Length - clip; i++)
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{
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//note we are exhaustively recalculating sums, we can do this much better without a doubt, but lets get the
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//first method done (brute force)
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//also note, definite integral doesn't include last point, so we have to add one point back in
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double integral = Integral.DefiniteIntegral(resultant.FilteredEU, i, i + clip, SPS);
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double hic = clipInSeconds * Math.Pow(integral / clipInSeconds, 2.5D);
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if (hic > maxHIC) { maxHIC = hic; maxHICPoint = i; maxHICEndPoint = i + clip; }
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}
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}
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return new HICResult(maxHIC, clipLengthMS, maxHICPoint, maxHICEndPoint);
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}
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/// <summary>
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/// helper class for storing/handling hic results
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/// </summary>
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public class HICResult
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{
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public int StartSample { get; }
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public int EndSample { get; }
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public int HicLengthMS { get; }
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public double HIC { get; }
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/// <summary>
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/// constructs a new HIC result
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/// </summary>
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/// <param name="hic">HIC value</param>
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/// <param name="hicLength">length of HIC in ms</param>
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/// <param name="endSample">start sample of HIC</param>
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/// <param name="startSample">end sample of HIC</param>
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public HICResult(double hic, int hicLength, int startSample, int endSample)
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{
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StartSample = startSample;
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EndSample = endSample;
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HicLengthMS = hicLength;
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HIC = hic;
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}
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}
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}
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}
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