public List <DeconvolutedEnvelope> RunEnvelopeParsimony(List <DeconvolutedEnvelope> envelopeCandidates, MzSpectrum spectrum)
{
var parsimoniousEnvelopes = new List <DeconvolutedEnvelope>();
var peaksBuffer = new List <DeconvolutedPeak>();
HashSet <double> mzsClaimed = new HashSet <double>();
List <DeconvolutedEnvelope> overlappingEnvelopes = new List <DeconvolutedEnvelope>();
// greedy algorithm. pick a set of mutually-exclusive isotopic envelopes, ordered by score,
// until no more envelopes can be found in the spectrum
DeconvolutedEnvelope nextEnvelope = GetNextBestEnvelope(envelopeCandidates, null);
bool harmonicsRemoved = false;
while (nextEnvelope != null)
{
DeconvolutedEnvelope chosenEnvelope = nextEnvelope;
parsimoniousEnvelopes.Add(chosenEnvelope);
foreach (var peak in chosenEnvelope.Peaks)
{
mzsClaimed.Add(peak.ExperimentalMz);
}
overlappingEnvelopes.Clear();
overlappingEnvelopes.AddRange(envelopeCandidates.Where(p => p.Peaks.Any(v => mzsClaimed.Contains(v.ExperimentalMz))));
foreach (DeconvolutedEnvelope overlappingEnvelope in overlappingEnvelopes.OrderByDescending(p => p.Score))
{
int mzIndex = spectrum.GetClosestPeakIndex(overlappingEnvelope.Peaks.First().ExperimentalMz);
int candidateEnvelopeIndex = envelopeCandidates.IndexOf(overlappingEnvelope);
DeconvolutedEnvelope redeconEnv = GetIsotopicEnvelope(spectrum, mzIndex, overlappingEnvelope.Charge, peaksBuffer, mzsClaimed);
if (redeconEnv != null)
{
redeconEnv.NoiseFwhm = overlappingEnvelope.NoiseFwhm;
redeconEnv.SignalToNoise = overlappingEnvelope.SignalToNoise;
redeconEnv.Baseline = overlappingEnvelope.Baseline;
}
envelopeCandidates[candidateEnvelopeIndex] = redeconEnv;
}
// remove all invalid isotopic envelopes
envelopeCandidates.RemoveAll(p => p == null);
//remove harmonics
if (chosenEnvelope.MonoisotopicMass > 10000 && !harmonicsRemoved)
{
RemoveHarmonics(envelopeCandidates, chosenEnvelope, spectrum);
harmonicsRemoved = true;
}
// get the next-best envelope
nextEnvelope = GetNextBestEnvelope(envelopeCandidates, chosenEnvelope);
}
return(parsimoniousEnvelopes);
}
public List <DeconvolutedEnvelope> GetEnvelopeCandidates(MzSpectrum spectrum, MzRange mzRange, List <int> optionalIndicies = null)
{
List <DeconvolutedEnvelope> envelopeCandidates = new List <DeconvolutedEnvelope>();
List <DeconvolutedPeak> peaksBuffer = new List <DeconvolutedPeak>();
HashSet <double> mzsClaimed = new HashSet <double>(); // this is empty, no m/z peaks have been claimed yet
HashSet <int> potentialChargeStates = new HashSet <int>();
// get list of envelope candidates for this scan
for (int p = 0; p < spectrum.XArray.Length; p++)
{
double mz = spectrum.XArray[p];
if (optionalIndicies != null && !optionalIndicies.Contains(p))
{
continue;
}
// check to see if this peak is in the m/z deconvolution range
if (mz < mzRange.Minimum)
{
continue;
}
else if (mz > mzRange.Maximum)
{
break;
}
// get rough list of charge states to check for based on m/z peaks around this peak
potentialChargeStates = GetPotentialChargeStates(potentialChargeStates, spectrum, p);
// examine different charge state possibilities and get corresponding envelope candidates
foreach (int z in potentialChargeStates)
{
DeconvolutedEnvelope candidateEnvelope = GetIsotopicEnvelope(spectrum, p, z, peaksBuffer, mzsClaimed);
if (candidateEnvelope != null)
{
envelopeCandidates.Add(candidateEnvelope);
}
}
}
return(envelopeCandidates);
}
public void RemoveHarmonics(List <DeconvolutedEnvelope> envelopeCandidates, DeconvolutedEnvelope previousBestEnvelope, MzSpectrum spectrum)
{
List <DeconvolutedEnvelope> harmonicEnvelopes = new List <DeconvolutedEnvelope>();
foreach (DeconvolutedEnvelope envelope in envelopeCandidates)
{
for (int i = 2; i < MaxCharge / envelope.Charge; i++)
{
int harmonicZ = envelope.Charge * i;
double mainMz = envelope.Peaks.First().ExperimentalMz;
var theoreticalHarmonicMz = (mainMz.ToMass(harmonicZ) + Constants.C13MinusC12).ToMz(harmonicZ);
int ind = spectrum.GetClosestPeakIndex(theoreticalHarmonicMz);
double experimentalHarmonicMz = spectrum.XArray[ind];
if (PpmTolerance.Within(experimentalHarmonicMz.ToMass(harmonicZ), theoreticalHarmonicMz.ToMass(harmonicZ)) &&
experimentalHarmonicMz != mainMz)
{
var harmonicCandidates = envelopeCandidates.Where(p => p.Charge == harmonicZ &&
p.Peaks.Any(v => v.ExperimentalMz == experimentalHarmonicMz || v.ExperimentalMz == mainMz))
.ToList(); // DEBUG
if (harmonicCandidates.Any())
{
harmonicEnvelopes.Add(envelope);
}
}
// TODO: look for -1 dalton peak
}
}
foreach (DeconvolutedEnvelope harmonicEnvelope in harmonicEnvelopes)
{
envelopeCandidates.Remove(harmonicEnvelope);
}
}
private DeconvolutedEnvelope GetNextBestEnvelope(List <DeconvolutedEnvelope> envelopeCandidates, DeconvolutedEnvelope previousBestEnvelope)
{
if (previousBestEnvelope == null)
{
return(envelopeCandidates.OrderByDescending(p => p.Score).FirstOrDefault());
}
List <DeconvolutedEnvelope> sameMassEnvelopes = new List <DeconvolutedEnvelope>();
for (int i = -3; i <= 3; i++)
{
double monoMass = i * Constants.C13MinusC12 + previousBestEnvelope.MonoisotopicMass;
sameMassEnvelopes.AddRange(envelopeCandidates.Where(p => PpmTolerance.Within(p.MonoisotopicMass, monoMass)));
}
if (sameMassEnvelopes.Any())
{
return(sameMassEnvelopes.OrderByDescending(p => p.Score).FirstOrDefault());
}
return(envelopeCandidates.OrderByDescending(p => p.Score).FirstOrDefault());
}
public DeconvolutedEnvelope GetIsotopicEnvelope(MzSpectrum spectrum, int p, int z, List <DeconvolutedPeak> deconvolutedPeaks,
HashSet <double> alreadyClaimedMzs)
{
double mz = spectrum.XArray[p];
double intensity = spectrum.YArray[p];
if (alreadyClaimedMzs.Contains(mz))
{
return(null);
}
deconvolutedPeaks.Clear();
double mass = mz.ToMass(z);
// get the index of an averagine envelope close in mass
int massIndex = GetMassIndex(mass) + 1;
if (massIndex >= mostIntenseMasses.Length)
{
return(null);
}
double[] averagineEnvelopeMasses = allMasses[massIndex];
double[] averagineEnvelopeIntensities = allIntensities[massIndex];
double monoMass = mass - diffToMonoisotopic[massIndex];
int indOfMostIntense = Array.IndexOf(averagineEnvelopeIntensities, 1);
// 1 is to the right, -1 is to the left in the envelope
int isotopeDirection = 1;
for (int i = indOfMostIntense; i < averagineEnvelopeMasses.Length && i >= 0; i += isotopeDirection)
{
double isotopeMassShift = averagineEnvelopeMasses[i] - averagineEnvelopeMasses[indOfMostIntense];
double isotopeTheoreticalMass = mass + isotopeMassShift;
double theoreticalIsotopeMz = isotopeTheoreticalMass.ToMz(z);
double theoreticalIsotopeIntensity = averagineEnvelopeIntensities[i] * intensity;
var peakIndex = spectrum.GetClosestPeakIndex(theoreticalIsotopeMz);
//TODO: look for other peaks in the scan that could be this isotope that meet the m/z tolerance
var isotopeExperMz = spectrum.XArray[peakIndex];
var isotopeExperIntensity = spectrum.YArray[peakIndex];
double intensityRatio = isotopeExperIntensity / theoreticalIsotopeIntensity;
double isotopeExperimentalMass = isotopeExperMz.ToMass(z);
bool withinMassTol = PpmTolerance.Within(isotopeExperMz.ToMass(z), isotopeTheoreticalMass);
bool withinIntensityTol = intensityRatio < IntensityRatioLimit && intensityRatio > 1 / IntensityRatioLimit;
bool unclaimedMz = !alreadyClaimedMzs.Contains(isotopeExperMz) && !deconvolutedPeaks.Select(p => p.ExperimentalMz).Contains(isotopeExperMz);
if (withinMassTol && // check mass tolerance
withinIntensityTol && // check intensity tolerance
unclaimedMz) // check to see if this peak has already been claimed by another envelope or this envelope
{
deconvolutedPeaks.Add(new DeconvolutedPeak(isotopeExperMz, theoreticalIsotopeMz, z, isotopeExperIntensity,
theoreticalIsotopeIntensity, i, averagineEnvelopeIntensities[i]));
}
else
{
if (isotopeDirection == 1)
{
isotopeDirection = -1;
i = indOfMostIntense;
}
else
{
break;
}
}
}
if (deconvolutedPeaks.Count < 2)
{
return(null);
}
// calculate % intensity missing
double sumIntensity = deconvolutedPeaks.Sum(p => Math.Min(p.ExperimentalIntensity, p.TheoreticalIntensity));
double expectedTotalIntensity = 0;
double maxTheorIntensity = deconvolutedPeaks.First().TheoreticalIntensity;
for (int i = 0; i < averagineEnvelopeIntensities.Length; i++)
{
double expectedIsotopeIntensity = averagineEnvelopeIntensities[i] * maxTheorIntensity;
expectedTotalIntensity += expectedIsotopeIntensity;
}
double fracIntensityObserved = sumIntensity / expectedTotalIntensity;
if (fracIntensityObserved < MinFractionIntensityRequired)
{
return(null);
}
// calculate correlation to averagine
double corr = Correlation.Pearson(deconvolutedPeaks.Select(p => p.ExperimentalIntensity), deconvolutedPeaks.Select(p => p.TheoreticalIntensity));
DeconvolutedEnvelope env = null;
// this is just to save memory, but quality filtering can happen outside of this method after the envelope has been returned, if desired
if (corr >= PearsonCorrelationRequired)
{
// create + return the isotopic envelope object
env = new DeconvolutedEnvelope(deconvolutedPeaks.ToList(), monoMass, z, corr, fracIntensityObserved);
}
else
{
// see if a subset of the peaks is a valid envelope
List <DeconvolutedEnvelope> subsetEnvelopeCandidates = new List <DeconvolutedEnvelope>();
//TODO: calculate subsets of peaks that have been gathered. return the best one that meets the filtering criteria,
// or all of the ones that meet the filtering criteria?
var sortedPeaks = deconvolutedPeaks.OrderBy(p => p.TheoreticalMz).ToList();
List <DeconvolutedPeak> subsetPeaks = new List <DeconvolutedPeak>();
for (int start = 0; start < sortedPeaks.Count; start++)
{
for (int end = sortedPeaks.Count - 1; end >= start + 1; end--)
{
subsetPeaks.Clear();
for (int k = start; k <= end; k++)
{
subsetPeaks.Add(sortedPeaks[k]);
}
//TODO: make this more efficient by changing start + end
if (!subsetPeaks.Any(p => p.ExperimentalMz == mz))
{
continue;
}
corr = Correlation.Pearson(subsetPeaks.Select(p => p.ExperimentalIntensity), subsetPeaks.Select(p => p.TheoreticalIntensity));
sumIntensity = subsetPeaks.Sum(p => Math.Min(p.ExperimentalIntensity, p.TheoreticalIntensity));
fracIntensityObserved = sumIntensity / expectedTotalIntensity;
if (corr >= PearsonCorrelationRequired && fracIntensityObserved >= MinFractionIntensityRequired && subsetPeaks.Count >= 2)
{
var subsetEnvelope = new DeconvolutedEnvelope(subsetPeaks.OrderBy(p => Math.Abs(p.ExperimentalMz - mz)).ToList(),
monoMass, z, corr, fracIntensityObserved);
subsetEnvelopeCandidates.Add(subsetEnvelope);
}
}
}
// use the best subset isotopic envelope
env = subsetEnvelopeCandidates.OrderByDescending(p => p.Score).FirstOrDefault();
}
return(env);
}
