MCH Match index in mc tables (#928)

* fixing the MCH index in MC

Author: batoul-d

PWGDQ/TableProducer/tableMakerMC.cxx

@@ -462,10 +462,53 @@ struct TableMakerMC {
 
         auto groupedMuons = tracksMuon.sliceBy(aod::fwdtrack::collisionId, collision.globalIndex());
         // loop over muons
+
+        // first we need to get the correct indices
+        int nDel = 0;
+        int idxPrev = -1;
+        std::map<int, int> newEntryNb;
+        std::map<int, int> newMatchIndex;
+
         for (auto& muon : groupedMuons) {
           trackFilteringTag = uint64_t(0);
           trackTempFilterMap = uint8_t(0);
 
+          if (!muon.has_mcParticle()) {
+            continue;
+          }
+
+          VarManager::FillTrack<TMuonFillMap>(muon);
+
+          if (muon.index() > idxPrev + 1) { // checks if some muons are filtered even before the skimming function
+            nDel += muon.index() - (idxPrev + 1);
+          }
+          idxPrev = muon.index();
+
+          // check the cuts and filters
+          int i = 0;
+          for (auto& cut : fMuonCuts) {
+            if (cut.IsSelected(VarManager::fgValues)) {
+              trackTempFilterMap |= (uint8_t(1) << i);
+              if (!fConfigNoQA) {
+                fHistMan->FillHistClass(Form("Muons_%s", cut.GetName()), VarManager::fgValues);
+              }
+              ((TH1I*)fStatsList->At(2))->Fill(float(i));
+            }
+            i++;
+          }
+          if (!trackTempFilterMap) { // does not pass the cuts
+            nDel++;
+          } else { // it passes the cuts and will be saved in the tables
+            newEntryNb[muon.index()] = muon.index() - nDel;
+          }
+        }
+
+        // now let's save the muons with the correct indices and matches
+        for (auto& muon : groupedMuons) {
+
+          trackFilteringTag = uint64_t(0);
+          trackTempFilterMap = uint8_t(0);
+
           if (!muon.has_mcParticle()) {
             continue;
           }
@@ -523,10 +566,33 @@ struct TableMakerMC {
             fCounters[0]++;
           }
 
+          // update the matching MCH/MFT index
+
+          if (int(muon.trackType()) == 0 || int(muon.trackType()) == 2) { // MCH-MFT or GLB track
+            int matchIdx = muon.matchMCHTrackId() - muon.offsets();
+            if (newEntryNb.count(matchIdx) > 0) {                                                  // if the key exists which means the match will not get deleted
+              newMatchIndex[muon.index()] = newEntryNb[matchIdx];                                  // update the match for this muon to the updated entry of the match
+              newMatchIndex[muon.index()] += muonBasic.lastIndex() + 1 - newEntryNb[muon.index()]; // adding the offset of muons, muonBasic.lastIndex() start at -1
+              if (int(muon.trackType()) == 0) {                                                    // for now only do this to global tracks
+                newMatchIndex[matchIdx] = newEntryNb[muon.index()];                                // add the  updated index of this muon as a match to mch track
+                newMatchIndex[matchIdx] += muonBasic.lastIndex() + 1 - newEntryNb[muon.index()];   // adding the offset, muonBasic.lastIndex() start at -1
+              }
+            } else {
+              newMatchIndex[muon.index()] = -1;
+            }
+          }
+
+          else if (int(muon.trackType() == 4)) { // an MCH track
+            // in this case the matches should be filled from the other types but we need to check
+            if (newMatchIndex.count(muon.index()) == 0) {
+              newMatchIndex[muon.index()] = -1;
+            }
+          }
+
           muonBasic(event.lastIndex(), trackFilteringTag, muon.pt(), muon.eta(), muon.phi(), muon.sign());
           muonExtra(muon.nClusters(), muon.pDca(), muon.rAtAbsorberEnd(),
                     muon.chi2(), muon.chi2MatchMCHMID(), muon.chi2MatchMCHMFT(),
-                    muon.matchScoreMCHMFT(), muon.matchMCHTrackId(), muon.mchBitMap(), muon.midBitMap(), muon.midBoards(), muon.trackType());
+                    muon.matchScoreMCHMFT(), newMatchIndex.find(muon.index())->second, muon.mchBitMap(), muon.midBitMap(), muon.midBoards(), muon.trackType());
           if constexpr (static_cast<bool>(TMuonFillMap & VarManager::ObjTypes::MuonCov)) {
             muonCov(muon.x(), muon.y(), muon.z(), muon.phi(), muon.tgl(), muon.signed1Pt(),
                     muon.cXX(), muon.cXY(), muon.cYY(), muon.cPhiX(), muon.cPhiY(), muon.cPhiPhi(),