map<Size, PeakSpectrum > PScore::calculatePeakLevelSpectra(const PeakSpectrum& spec, const vector<Size>& ranks, Size min_level, Size max_level) { map<Size, MSSpectrum<Peak1D> > peak_level_spectra; if (spec.empty()) return peak_level_spectra; // loop over all peaks and associated (zero-based) ranks for (Size i = 0; i != ranks.size(); ++i) { // start at the highest (less restrictive) level for (int j = static_cast<int>(max_level); j >= static_cast<int>(min_level); --j) { // if the current peak is annotated to have lower or equal rank then allowed for this peak level add it if (static_cast<int>(ranks[i]) <= j) { peak_level_spectra[j].push_back(spec[i]); } else { // if the current peak has higher rank than the current level then all it is also to high for the lower levels break; } } } return peak_level_spectra; }
PeptideHit AScore::compute(const PeptideHit & hit, PeakSpectrum & real_spectrum, double fragment_mass_tolerance, bool fragment_mass_unit_ppm, Size max_peptide_len, Size max_num_perm) { PeptideHit phospho = hit; //reset phospho phospho.setScore(-1); if (real_spectrum.empty()) { return phospho; } String sequence_str = phospho.getSequence().toString(); Size number_of_phosphorylation_events = numberOfPhosphoEvents_(sequence_str); AASequence seq_without_phospho = removePhosphositesFromSequence_(sequence_str); if (seq_without_phospho.toUnmodifiedString().size() > max_peptide_len) { LOG_DEBUG << "\tcalculation aborted: peptide too long: " << seq_without_phospho.toString() << std::endl; return phospho; } // determine all phospho sites vector<Size> sites(getSites_(seq_without_phospho)); Size number_of_STY = sites.size(); if (number_of_phosphorylation_events == 0 || number_of_STY == 0 || number_of_STY == number_of_phosphorylation_events) { return phospho; } vector<vector<Size> > permutations(computePermutations_(sites, (Int)number_of_phosphorylation_events)); LOG_DEBUG << "\tnumber of permutations: " << permutations.size() << std::endl; // TODO: using a heuristic to calculate the best phospho sites if the number of permutations are exceeding the maximum. // A heuristic could be to calculate the best site for the first phosphorylation and based on this the best site for the second // phosphorylation and so on until every site is determined if (permutations.size() > max_num_perm) { LOG_DEBUG << "\tcalculation aborted: number of permutations exceeded" << std::endl; return phospho; } vector<PeakSpectrum> th_spectra(createTheoreticalSpectra_(permutations, seq_without_phospho)); // prepare real spectrum windows if (!real_spectrum.isSorted()) { real_spectrum.sortByPosition(); } vector<PeakSpectrum> windows_top10(peakPickingPerWindowsInSpectrum_(real_spectrum)); // calculate peptide score for each possible phospho site permutation vector<vector<double> > peptide_site_scores(calculatePermutationPeptideScores_(th_spectra, windows_top10, fragment_mass_tolerance, fragment_mass_unit_ppm)); // rank peptide permutations ascending multimap<double, Size> ranking(rankWeightedPermutationPeptideScores_(peptide_site_scores)); multimap<double, Size>::reverse_iterator rev = ranking.rbegin(); String seq1 = th_spectra[rev->second].getName(); phospho.setSequence(AASequence::fromString(seq1)); phospho.setMetaValue("search_engine_sequence", hit.getSequence().toString()); double peptide1_score = rev->first; phospho.setMetaValue("AScore_pep_score", peptide1_score); // initialize score with highest peptide score (aka highest weighted score) ++rev; String seq2 = th_spectra[rev->second].getName(); double peptide2_score = rev->first; vector<ProbablePhosphoSites> phospho_sites; determineHighestScoringPermutations_(peptide_site_scores, phospho_sites, permutations, ranking); Int rank = 1; double best_Ascore = std::numeric_limits<double>::max(); // the lower the better for (vector<ProbablePhosphoSites>::iterator s_it = phospho_sites.begin(); s_it != phospho_sites.end(); ++s_it) { double Ascore = 0; if (peptide1_score == peptide2_score) // set Ascore = 0 for each phosphorylation site { LOG_DEBUG << "\tscore of best (" << seq1 << ") and second best peptide (" << seq2 << ") are equal (" << peptide1_score << ")" << std::endl; } else { vector<PeakSpectrum> site_determining_ions; computeSiteDeterminingIons_(th_spectra, *s_it, site_determining_ions, fragment_mass_tolerance, fragment_mass_unit_ppm); Size N = site_determining_ions[0].size(); // all possibilities have the same number so take the first one double p = static_cast<double>(s_it->peak_depth) / 100.0; Size n_first = 0; // number of matching peaks for first peptide for (Size window_idx = 0; window_idx != windows_top10.size(); ++window_idx) // for each 100 m/z window { n_first += numberOfMatchedIons_(site_determining_ions[0], windows_top10[window_idx], s_it->peak_depth, fragment_mass_tolerance, fragment_mass_unit_ppm); } double P_first = computeCumulativeScore_(N, n_first, p); Size n_second = 0; // number of matching peaks for second peptide for (Size window_idx = 0; window_idx < windows_top10.size(); ++window_idx) //each 100 m/z window { n_second += numberOfMatchedIons_(site_determining_ions[1], windows_top10[window_idx], s_it->peak_depth, fragment_mass_tolerance, fragment_mass_unit_ppm); } Size N2 = site_determining_ions[1].size(); // all possibilities have the same number so take the first one double P_second = computeCumulativeScore_(N2, n_second, p); //abs is used to avoid -0 score values double score_first = abs(-10 * log10(P_first)); double score_second = abs(-10 * log10(P_second)); LOG_DEBUG << "\tfirst - N: " << N << ",p: " << p << ",n: " << n_first << ", score: " << score_first << std::endl; LOG_DEBUG << "\tsecond - N: " << N2 << ",p: " << p << ",n: " << n_second << ", score: " << score_second << std::endl; Ascore = score_first - score_second; LOG_DEBUG << "\tAscore_" << rank << ": " << Ascore << std::endl; } if (Ascore < best_Ascore) { best_Ascore = Ascore; } phospho.setMetaValue("AScore_" + String(rank), Ascore); ++rank; } phospho.setScore(best_Ascore); return phospho; }