Added a new output module to write ROOT histograms

CepGen/CMakeLists.txt

@@ -99,7 +99,7 @@ endif()
 if(ROOT_FOUND)
   message(STATUS "ROOT found in ${ROOT_LIBRARY_DIR}")
   list(APPEND addons_libraries ${ROOT_LIBRARIES})
-  list(APPEND io_sources "IO/ROOTTreeHandler.cpp")
+  list(APPEND io_sources "IO/ROOTHandler.cpp" "IO/ROOTTreeHandler.cpp")
   include_directories(${ROOT_INCLUDE_DIRS})
   link_directories(${ROOT_LIBRARY_DIR})
   if(DELPHES)

CepGen/IO/ROOTHandler.cpp

@@ -0,0 +1,82 @@
+#include "CepGen/IO/ExportHandler.h"
+
+#include "CepGen/Core/Exception.h"
+#include "CepGen/Core/ParametersList.h"
+#include "CepGen/Core/utils.h"
+
+#include "CepGen/Event/Event.h"
+#include "CepGen/Event/EventBrowser.h"
+#include "CepGen/Parameters.h"
+
+#include "CepGen/Version.h"
+
+#include "TFile.h"
+#include "TH1.h"
+
+namespace cepgen
+{
+  namespace io
+  {
+    /**
+     * \brief Handler for the generic ROOT file output
+     * \author Laurent Forthomme <laurent.forthomme@cern.ch>
+     * \date Jul 2019
+     */
+    class ROOTHandler : public GenericExportHandler
+    {
+      public:
+        explicit ROOTHandler( const ParametersList& );
+        ~ROOTHandler();
+
+        void initialise( const Parameters& ) override {}
+        void setCrossSection( double xsec, double ) override { xsec_ = xsec; }
+        void operator<<( const Event& ) override;
+
+      private:
+        std::unique_ptr<TFile> file_;
+        std::vector<std::pair<std::string,TH1*> > hists_;
+        const ParametersList variables_;
+
+        double xsec_;
+        const utils::EventBrowser browser_;
+    };
+
+    ROOTHandler::ROOTHandler( const ParametersList& params ) :
+      GenericExportHandler( "text" ),
+      file_     ( TFile::Open( params.get<std::string>( "filename", "output.root" ).c_str(), "recreate" ) ),
+      variables_( params.get<ParametersList>( "variables" ) ),
+      xsec_( 1. )
+    {
+      //--- extract list of variables to be plotted in histograms
+      for ( const auto& var : variables_.keys() ) {
+        const auto& hvar = variables_.get<ParametersList>( var );
+        const int nbins = hvar.get<int>( "nbins", 10 );
+        const double min = hvar.get<double>( "low", 0. ), max = hvar.get<double>( "high", 1. );
+        const auto title = Form( "%s;%s;d#sigma/d(%s) (pb/bin)", var.c_str(), var.c_str(), var.c_str() );
+        hists_.emplace_back( std::make_pair( var, new TH1D( var.c_str(), title.c_str(), nbins, min, max ) ) );
+        CG_INFO( "ROOTHandler" )
+          << "Booking a histogram with " << nbins << " bin" << utils::s( nbins )
+          << " between " << min << " and " << max << " for \"" << var << "\".";
+      }
+    }
+
+    ROOTHandler::~ROOTHandler()
+    {
+      //--- finalisation of the output file
+      for ( const auto& hist : hists_ )
+        hist.second->Write( hist.first.c_str() );
+        // ROOT and its sumptuous memory management disallows the "delete" here
+      file_->Close();
+    }
+
+    void
+    ROOTHandler::operator<<( const Event& ev )
+    {
+      //--- increment the corresponding histograms
+      for ( const auto& h_var : hists_ )
+        h_var.second->Fill( browser_.get( ev, h_var.first ), xsec_ );
+    }
+  }
+}
+
+REGISTER_IO_MODULE( root, ROOTHandler )