82 lines
2.3 KiB
Swift
82 lines
2.3 KiB
Swift
import ComplexModule
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import Foundation
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import PFFFT
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import RealModule
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public struct ECGSynRRGenerator: ~Copyable {
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let nrr: Int
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let fft: FFT<Double>
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let spectrum: Buffer<Complex<Double>>
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let signal: Buffer<Double>
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var rng: RandomNumberGenerator
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// mean and standard deviation of RR intervals
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let rrMean: Double
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let rrStd: Double
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let timeParameters: TimeParameters
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public init(params: TimeParameters) {
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typealias FFT = PFFFT.FFT<Double>
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let sr = params.srInternal
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rrMean = 60.0 / params.hrMean
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rrStd = 60.0 * params.hrStd / (params.hrMean * params.hrMean)
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nrr = FFT.nearestValidSize(params.numBeats * sr * Int(rrMean.rounded(.up)), higher: true)
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fft = try! FFT(n: nrr)
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spectrum = fft.makeSpectrumBuffer(extra: 1)
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signal = fft.makeSignalBuffer()
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timeParameters = params
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rng = Xoshiro256Plus(seed: params.seed)
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}
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public mutating func generateSeries(params: RRParameters) -> ECGSynRRSeries<Double> {
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let rr = generateSignal(params: params)
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return ECGSynRRSeries(timeParameters: timeParameters, rrParamaters: params, rng: rng, signal: rr)
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}
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public mutating func generateSignal(params: RRParameters) -> [Double] {
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let w1 = 2.0 * .pi * params.flo
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let w2 = 2.0 * .pi * params.fhi
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let c1 = 2.0 * .pi * params.flostd
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let c2 = 2.0 * .pi * params.fhistd
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let sig2 = 1.0
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let sig1 = params.lfhfRatio
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let sr = Double(timeParameters.srInternal)
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let dw = (sr / Double(nrr)) * 2.0 * .pi
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spectrum.mapInPlaceSwapLast { i in
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let w = dw * Double(i)
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let dw1 = w - w1
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let dw2 = w - w2
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let hw = sig1 * exp(-dw1 * dw1 / (2.0 * c1 * c1)) / sqrt(2.0 * .pi * c1 * c1)
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+ sig2 * exp(-dw2 * dw2 / (2.0 * c2 * c2)) / sqrt(2.0 * .pi * c2 * c2)
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let sw = (sr / 2.0) * sqrt(hw)
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let ph = 2.0 * .pi * rng.nextDouble()
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return Complex(length: sw, phase: ph)
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}
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fft.inverse(spectrum: spectrum, signal: signal)
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var rr = signal.map { $0 * 1.0 / Double(nrr) }
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let xstd = stdev(rr)
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let ratio = rrStd / xstd
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for i in 0 ..< nrr {
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rr[i] = rr[i] * ratio + rrMean
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}
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return rr
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}
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}
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