FWLite/interface/FWLiteAnalyzerWrapper.h

0001 #ifndef PhysicsTools_FWLite_interface_FWLiteAnalyzerWrapper_h
0002 #define PhysicsTools_FWLite_interface_FWLiteAnalyzerWrapper_h
0003
0004 #include <string>
0005 #include <vector>
0006 #include <iostream>
0007
0008 #include <TFile.h>
0009 #include <TSystem.h>
0010
0011 #include "DataFormats/FWLite/interface/ChainEvent.h"
0012 #include "DataFormats/FWLite/interface/InputSource.h"
0013 #include "DataFormats/FWLite/interface/OutputFiles.h"
0014 #include "FWCore/FWLite/interface/FWLiteEnabler.h"
0015 #include "FWCore/ParameterSet/interface/ProcessDesc.h"
0016 #include "PhysicsTools/FWLite/interface/TFileService.h"
0017
0018 /**
0019   \class    FWLiteAnalyzerWrapper FWLiteAnalyzerWrapper.h "PhysicsTools/FWLite/interface/FWLiteAnalyzerWrapper.h"
0020   \brief    Wrapper class for classes of type BasicAnalyzer to "convert" them into a full a basic FWLiteAnalyzer
0021
0022    This template class is a wrapper round classes of type BasicAnalyzer as defined in in the
0023    BasicAnalyzer.h file of this package. From this class the wrapper expects the following
0024    member functions:
0025
0026    + a contructor with a const edm::ParameterSet& and a TFileDirectory& as input.
0027    + a beginJob function
0028    + a endJob function
0029    + a analyze function with an const edm::EventBase& as input
0030
0031    these functions are called within the wrapper. The wrapper translates the common class into
0032    a basic FWLiteAnalyzer, which provides basic functionality of reading configuration files
0033    and event looping. An example of an application given in the PatExamples package is shown
0034    below:
0035
0036    #include "PhysicsTools/PatExamples/interface/BasicMuonAnalyzer.h"
0037    #include "PhysicsTools/FWLite/interface/FWLiteAnalyzerWrapper.h"
0038
0039    typedef fwlite::AnalyzerWrapper<BasicMuonAnalyzer> WrappedFWLiteAnalyzer;
0040
0041    int main(int argc, char* argv[])
0042    {
0043      // load framework libraries
0044      gSystem->Load( "libFWCoreFWLite" );
0045      FWLiteEnabler::enable();
0046
0047      // only allow one argument for this simple example which should be the
0048      // the python cfg file
0049      if ( argc < 2 ) {
0050        std::cout << "Usage : " << argv[0] << " [parameters.py]" << std::endl;
0051        return 0;
0052      }
0053
0054      // get the python configuration
0055      PythonProcessDesc builder(argv[1]);
0056      WrappedFWLiteAnalyzer ana(*(builder.processDesc()->getProcessPSet()), std::string("MuonAnalyzer"), std::string("analyzeBasicPat"));
0057      ana.beginJob();
0058      ana.analyze();
0059      ana.endJob();
0060      return 0;
0061    }
0062
0063    The configuration file for this FWLiteAnalyzer is expected to have the following structure:
0064
0065    import FWCore.ParameterSet.Config as cms
0066
0067    process = cms.Process("FWLitePlots")
0068
0069    process.fwliteInput = cms.PSet(
0070          fileNames = cms.untracked.vstring('file:patTuple.root'),  ## mandatory
0071          maxEvents   = cms.int32(-1),                              ## optional
0072          outputEvery = cms.uint32(10),                             ## optional
0073    )
0074
0075    process.fwliteOutput = cms.PSet(
0076          fileName = cms.untracked.string('outputHistos.root')      ## mandatory
0077    )
0078
0079    process.muonAnalyzer = cms.PSet(
0080      muons = cms.InputTag('cleanPatMuons') ## input for the simple example above
0081    )
0082
0083
0084    where the parameters maxEvents and
0085    reportAfter are optional. If omitted all events in the file(s) will be looped and no progress
0086    report will be given. More input files can be given as a vector of strings. Potential histograms
0087    per default will be written directely into the file without any furhter directory structure. If
0088    the class is instantiated with an additional directory string a new directory with the
0089    corresponding name will be created and the histograms will be added to this directory.
0090    With these wrapper classes we have the use case in mind that you keep classes, which easily can
0091    be used both within the full framework and within FWLite.
0092
0093    NOTE: in the current implementation this wrapper class only supports basic event looping. For
0094    anytasks of more complexity we recommend you to start from a FWLiteAnalyzer class from the very
0095    beginning and just to stay within FWLite.
0096 */
0097
0098 namespace fwlite {
0099
0100   template <class T>
0101   class AnalyzerWrapper {
0102   public:
0103     /// default constructor
0104     AnalyzerWrapper(const edm::ParameterSet& cfg, std::string analyzerName, std::string directory = "");
0105     /// default destructor
0106     virtual ~AnalyzerWrapper() {}
0107     /// everything which has to be done before the event loop
0108     virtual void beginJob() { analyzer_->beginJob(); }
0109     /// everything which has to be done during the event loop. NOTE: the event will be looped inside this function
0110     virtual void analyze();
0111     /// everything which has to be done after the event loop
0112     virtual void endJob() { analyzer_->endJob(); }
0113
0114   protected:
0115     /// helper class  for input parameter handling
0116     fwlite::InputSource inputHandler_;
0117     /// helper class for output file handling
0118     fwlite::OutputFiles outputHandler_;
0119     /// maximal number of events to be processed (-1 means to loop over all event)
0120     int maxEvents_;
0121     /// number of events after which the progress will be reported (0 means no report)
0122     unsigned int reportAfter_;
0123     /// TFileService for histogram management
0124     fwlite::TFileService fileService_;
0125     /// derived class of type BasicAnalyzer
0126     std::shared_ptr<T> analyzer_;
0127   };
0128
0129   /// default contructor
0130   template <class T>
0131   AnalyzerWrapper<T>::AnalyzerWrapper(const edm::ParameterSet& cfg, std::string analyzerName, std::string directory)
0132       : inputHandler_(cfg),
0133         outputHandler_(cfg),
0134         maxEvents_(inputHandler_.maxEvents()),
0135         reportAfter_(inputHandler_.reportAfter()),
0136         fileService_(outputHandler_.file()) {
0137     // analysis specific parameters
0138     const edm::ParameterSet& ana = cfg.getParameter<edm::ParameterSet>(analyzerName.c_str());
0139     if (directory.empty()) {
0140       // create analysis class of type BasicAnalyzer
0141       analyzer_ = std::shared_ptr<T>(new T(ana, fileService_));
0142     } else {
0143       // create a directory in the file if directory string is non empty
0144       TFileDirectory dir = fileService_.mkdir(directory);
0145       analyzer_ = std::shared_ptr<T>(new T(ana, dir));
0146     }
0147   }
0148
0149   /// everything which has to be done during the event loop. NOTE: the event will be looped inside this function
0150   template <class T>
0151   void AnalyzerWrapper<T>::analyze() {
0152     int ievt = 0;
0153     std::vector<std::string> const& inputFiles = inputHandler_.files();
0154     // loop the vector of input files
0155     fwlite::ChainEvent event(inputFiles);
0156     for (event.toBegin(); !event.atEnd(); ++event, ++ievt) {
0157       // break loop if maximal number of events is reached
0158       if (maxEvents_ > 0 ? ievt + 1 > maxEvents_ : false)
0159         break;
0160       // simple event counter
0161       if (reportAfter_ != 0 ? (ievt > 0 && ievt % reportAfter_ == 0) : false)
0162         std::cout << "  processing event: " << ievt << std::endl;
0163       // analyze event
0164       analyzer_->analyze(event);
0165     }
0166   }
0167 }  // namespace fwlite
0168
0169 #endif