bdskim.cc

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/* 
Beam Delivery Simulation (BDSIM) Copyright (C) BDSIM Collaboration, 2001 - 2026.
 
This file is part of BDSIM.
 
BDSIM is free software: you can redistribute it and/or modify 
it under the terms of the GNU General Public License as published 
by the Free Software Foundation version 3 of the License.
 
BDSIM is distributed in the hope that it will be useful, but 
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
 
You should have received a copy of the GNU General Public License
along with BDSIM.  If not, see <http://www.gnu.org/licenses/>.
*/
#include "AnalysisUtilities.hh"
#include "FileMapper.hh"
#include "Header.hh"
#include "SelectionLoader.hh"
 
#include "BDSOutputROOTEventHeader.hh"
 
#include "TFile.h"
#include "TTree.h"
 
#include <iostream>
#include <stdexcept>
#include <string>
#include <vector>
 
int main(int argc, char* argv[])
{
  if (argc < 3 || argc > 4)
    {
      std::cout << "usage: bdskim skimselection.txt input_bdsim_raw.root (output_bdsim_raw.root)" << std::endl;
      std::cout << "default output name if none given is <inputname>_skimmed.root" << std::endl;
      return 1;
    }
 
  std::string selectionFile = std::string(argv[1]);
  std::string inputFile     = std::string(argv[2]);
  std::string outputFile;
  if (argc == 4)
    {outputFile = std::string(argv[3]);}
  else
    {
      outputFile = RBDS::DefaultOutputName(inputFile, "_skimmed");
      std::cout << "Using default output file name with \"_skimmed\" suffix  : " << outputFile << std::endl;
    }
 
  // load selection
  std::string selection;
  try
    {selection = RBDS::LoadSelection(selectionFile);}
  catch (std::exception& e)
    {std::cerr << e.what() << std::endl; return 1;}
 
  // open and check input file
  TFile* input = new TFile(inputFile.c_str(),  "READ");
  if (!RBDS::IsBDSIMOutputFile(input))
    {
      std::cerr << inputFile << " is not a BDSIM output file" << std::endl;
      delete input;
      return 1;
    }
  
  // note we create trees in the new output file in order the same as the original to preserve the 'look' of the file
 
  TTree* headerTree = dynamic_cast<TTree*>(input->Get("Header")); // should be safe given check we've just done
  if (!headerTree)
    {std::cerr << "Error with header" << std::endl; return 1;}
  Header* headerLocal = new Header();
  headerLocal->SetBranchAddress(headerTree);
  Long64_t nEntriesHeader = headerTree->GetEntries();
  headerTree->GetEntry(nEntriesHeader - 1); // get the last entry (2nd is more up to date if it exists)
  // We also want to explicitly copy the skim variables that might only be known in the 2nd instance.
  BDSOutputROOTEventHeader* headerOut = new BDSOutputROOTEventHeader(*(headerLocal->header));
  headerOut->skimmedFile = true;
  
  TFile* output = new TFile(outputFile.c_str(), "RECREATE");
  if (output->IsZombie())
    {std::cerr << "Couldn't open output file " << outputFile << std::endl; return 1;}
  output->cd();
  TTree* outputHeaderTree = new TTree("Header", "BDSIM Header");
  outputHeaderTree->Branch("Header.", "BDSOutputROOTEventHeader", headerOut);
  outputHeaderTree->Fill();
 
  std::vector<std::string> treeNames = {"ParticleData", "Beam", "Options", "Model", "Run"};
  for (const auto& tn : treeNames)
    {
      TTree* original = dynamic_cast<TTree*>(input->Get(tn.c_str()));
      if (!original)
        {
          std::cerr << "Failed to load Tree named " << tn << std::endl;
          delete output;
          delete input;
          return 1;
        }
      auto clone = original->CloneTree();
      clone->AutoSave();
    }
  
  TTree* allEvents = dynamic_cast<TTree*>(input->Get("Event"));
  if (!allEvents)
    {
      std::cerr << "No Event tree in file" << std::endl;
      delete input;
      return 1;
    }
  TTree* selectEvents = allEvents->CopyTree(selection.c_str());
  selectEvents->Write();
 
  output->Write(nullptr,TObject::kOverwrite);
  delete output;
  delete input;
  
  return 0;
}