MC/config/PWGEM: add Generator.C and ini for LF->ee/gamma in PWGEM (#1583)

Author: dsekihat

MC/config/PWGEM/external/generator/GeneratorCocktailWithGap.C

@@ -0,0 +1,149 @@
+#include <vector>
+
+using namespace o2::eventgen;
+
+// This is to evaluate MC efficiency. Not for comparison between data and LMEE cocktail.
+class GeneratorCocktailWithGap : public Generator
+{
+ public:
+   GeneratorCocktailWithGap() : Generator() {
+     lGeneratedEvents = 0;
+     lInverseTriggerRatio = 1;
+     mGeneratorsSig->clear();
+     mGeneratorsGap->clear();
+     mGeneratorsSig->shrink_to_fit();
+     mGeneratorsGap->shrink_to_fit();
+   };
+
+   GeneratorCocktailWithGap(int lInputTriggerRatio) : Generator() {
+     lGeneratedEvents = 0;
+     lInverseTriggerRatio = lInputTriggerRatio;
+     mGeneratorsSig->clear();
+     mGeneratorsGap->clear();
+     mGeneratorsSig->shrink_to_fit();
+     mGeneratorsGap->shrink_to_fit();
+   };
+
+  ~GeneratorCocktailWithGap() = default;
+
+  // at init we init all generators
+  bool Init() override
+  {
+    for (auto& g : *mGeneratorsSig) {
+      g->Init();
+    }
+    for (auto& g : *mGeneratorsGap) {
+      g->Init();
+    }
+
+    Generator::Init();
+    return true;
+  };
+
+  void setInputTriggerRatio(int lInputTriggerRatio) { lInverseTriggerRatio = lInputTriggerRatio; };
+
+  // call generate method for all generators
+  bool generateEvent() override
+  {
+    // Simple straightforward check to alternate generators
+    if (lGeneratedEvents % lInverseTriggerRatio == 0) {
+      // Generate event of interest
+      printf("generate signal event %lld\n", lGeneratedEvents);
+      for (auto& g : *mGeneratorsSig){
+        printf("generate signal event %s\n", g->GetName());
+        bool isOK = g->generateEvent();
+      }
+    } else {
+      // Generate gap event
+      printf("generate gap event %lld\n", lGeneratedEvents);
+      for (auto& g : *mGeneratorsGap){
+        printf("generate gap event %s\n", g->GetName());
+        bool isOK = g->generateEvent();
+      }
+    }
+    lGeneratedEvents++;
+    return true;
+  };
+
+  // at importParticles we add particles to the output particle vector
+  bool importParticles() override
+  {
+    //note that lGeneratedEvents++ is called in generateEvent();
+    if ((lGeneratedEvents-1) % lInverseTriggerRatio == 0) {
+      for (auto& g : *mGeneratorsSig) {
+        int nPart = mParticles.size();
+        g->importParticles();
+        printf("generator %s : ngen = %zu\n", g->GetName(), g->getParticles().size());
+        for (auto p : g->getParticles()) {
+          mParticles.push_back(p);
+          auto& pEdit = mParticles.back();
+          o2::mcutils::MCGenHelper::encodeParticleStatusAndTracking(pEdit);
+
+          if (pEdit.GetFirstMother() > -1){
+            pEdit.SetFirstMother(pEdit.GetFirstMother() + nPart);
+          }
+          if (pEdit.GetSecondMother() > -1){
+            pEdit.SetLastMother(pEdit.GetSecondMother() + nPart);
+          }
+          if (pEdit.GetFirstDaughter() > -1){
+            pEdit.SetFirstDaughter(pEdit.GetFirstDaughter() + nPart);
+          }
+          if (pEdit.GetLastDaughter() > -1){
+            pEdit.SetLastDaughter(pEdit.GetLastDaughter() + nPart);
+          }
+        }
+        g->clearParticles();
+      }
+    } else {
+      for (auto& g : *mGeneratorsGap) {
+        int nPart = mParticles.size();
+        g->importParticles();
+        printf("generator %s : ngen = %zu\n", g->GetName(), g->getParticles().size());
+        for (auto p : g->getParticles()) {
+          mParticles.push_back(p);
+          auto& pEdit = mParticles.back();
+          o2::mcutils::MCGenHelper::encodeParticleStatusAndTracking(pEdit);
+
+          if (pEdit.GetFirstMother() > -1){
+            pEdit.SetFirstMother(pEdit.GetFirstMother() + nPart);
+          }
+          if (pEdit.GetSecondMother() > -1){
+            pEdit.SetLastMother(pEdit.GetSecondMother() + nPart);
+          }
+          if (pEdit.GetFirstDaughter() > -1){
+            pEdit.SetFirstDaughter(pEdit.GetFirstDaughter() + nPart);
+          }
+          if (pEdit.GetLastDaughter() > -1){
+            pEdit.SetLastDaughter(pEdit.GetLastDaughter() + nPart);
+          }
+        }
+        g->clearParticles();
+      }
+    }
+
+    //maybe, it is better to implement mParticle.shrink_to_fit() in Generator::clearParticles();
+
+    return true;
+  };
+
+  void addGeneratorSig(Generator* gen, int ntimes = 1) {
+    for (int in = 0; in < ntimes; in++){
+      mGeneratorsSig->push_back(gen);
+    }
+  };
+  void addGeneratorGap(Generator* gen, int ntimes = 1) {
+    for (int in = 0; in < ntimes; in++){
+      mGeneratorsGap->push_back(gen);
+    }
+  };
+
+  std::vector<Generator*>* getGeneratorsSig() { return mGeneratorsSig; };
+  std::vector<Generator*>* getGeneratorsGap() { return mGeneratorsGap; };
+
+ private:
+  // Control gap-triggering
+  Long64_t lGeneratedEvents;
+  int lInverseTriggerRatio;
+  std::vector<Generator*>* mGeneratorsSig = new std::vector<Generator*>(); // vector of Generator for signal
+  std::vector<Generator*>* mGeneratorsGap = new std::vector<Generator*>(); // vector of Generator for gap
+};