read_and_write.cpp

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#include "read_test.h"
// podio specific includes
#include "podio/EventStore.h"
#include "podio/ROOTReader.h"
#include "podio/ROOTWriter.h"
 
int main() {
  auto reader = podio::ROOTReader();
  auto store = podio::EventStore();
  reader.openFile("example.root");
  store.setReader(&reader);
 
  // test writing a subset of the event to a new file
  auto writer = podio::ROOTWriter("example_copy.root", &store);
  writer.registerForWrite("info");
  writer.registerForWrite("mcparticles");
  writer.registerForWrite("hits");
  writer.registerForWrite("clusters");
 
  unsigned nEvents = reader.getEntries();
  for (unsigned i = 0; i < nEvents; ++i) {
    if (i % 1000 == 0) {
      std::cout << "reading event " << i << std::endl;
    }
    processEvent(store, i, reader.currentFileVersion());
 
    writer.writeEvent();
 
    store.clear();
    reader.endOfEvent();
  }
  reader.closeFile();
  return 0;
}