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--- fcs:eic:intro [2017/02/07 22:16]
hepsim17 [Reconstructed events]
+++ fcs:eic:intro [2017/04/04 15:36] (current)
hepsim17 [Using C++]
@@ Line 162: / Line 162: @@
   * fake rate (cannot be done with this sample!)
   * calculate Q2 and x_bj, check efficiency and resolutions for these variable
-====== Displaying reconstructed events ======
+====== Reconstructed events ======
@@ Line 192: / Line 193: @@
+====== Using C++ ======
+You can read SLCIO files using a C++ program. As usual, your program can look as this:
+<code cpp>
+string input="data.slcio";
+LCReader* lcReader = LCFactory::getInstance()->createLCReader() ;
+lcReader->open( infile1.c_str() ) ;
+LCEvent*  evt;
+int nEvents=0;
+while( (evt = lcReader->readNextEvent()) != 0 ) {
+      if (nEvents==0) UTIL::LCTOOLS::dumpEvent( evt ) ;
+           cout << "  Run : " << evt->getRunNumber() << " Detector: "      << evt->getDetectorName() <<  endl ;
+           const LCParameters& params=evt->getParameters();
+           // print stored EVGEN parameters
+           StringVec floatKeys ;
+           int nFloatParameters = params.getFloatKeys( floatKeys ).size() ;
+           for(int i=0; i< nFloatParameters ; i++ ){
+              FloatVec floatVec ;
+              params.getFloatVals(  floatKeys[i], floatVec ) ;
+              int nFloat  = floatVec.size()  ;
+              cout << " parameter " << floatKeys[i] << " [float]: " ;
+              for(int j=0; j< nFloat ; j++ ){
+                    cout << floatVec[j] << ", " ;
+                }
+               cout << endl ;
+               }
+   nEvents ++ ;
+   }
+  lcReader->close() ;
+</code>
+This code example shows how to print float parameters from the EVGEN level (copied from the input ProMC).
+Here is the example of all parameters (float, integers, strings):
+<hidden>
+<code cpp>
+ parameter EVGEN:Code [int]: 10,
+ parameter EVGEN:DIS:ISR [int]: 0,
+ parameter EVGEN:ID1 [int]: 11,
+ parameter EVGEN:ID2 [int]: 2212,
+ parameter EVGEN:ProcessID [int]: 10,
+ parameter EVGEN:AlphaQCD [float]: 0.00255778,
+ parameter EVGEN:AlphaQED [float]: 0.243193,
+ parameter EVGEN:DIS:Q2 [float]: 12.4407,
+ parameter EVGEN:DIS:W [float]: 69.6586,
+ parameter EVGEN:DIS:XBJ [float]: 0.00255778,
+ parameter EVGEN:DIS:YBJ [float]: 0.243193,
+ parameter EVGEN:EventsRequested [float]: 50000,
+ parameter EVGEN:PDF1 [float]: 0,
+ parameter EVGEN:PDF2 [float]: 0,
+ parameter EVGEN:Scale [float]: 69.6586,
+ parameter EVGEN:ScalePDF [float]: 12.4407,
+ parameter EVGEN:SigmaErrorPB [float]: 737.376,
+ parameter EVGEN:SigmaPB [float]: 164882,
+ parameter EVGEN:Weight [float]: 1,
+ parameter EVGEN:X1 [float]: 0.00255778,
+ parameter EVGEN:X2 [float]: 0.243193,
+ parameter EVGEN:eCM [float]: 141,
+ parameter _weight [float]: 1,
+ parameter EVGEN:Process [string]: e-p,
+ parameter GEANT4_VERSION [string]: 10.2.0,
+ parameter HepSim [string]: 1.1,
+ parameter ProcessID [string]: -1,
+ parameter SLIC_VERSION [string]: 5.0.0,
+</code>
+</hidden>
+For EIC ep events, the relevant parameters for a given DIS event are:
+<code cpp>
+ parameter EVGEN:eCM [float]: 141
+ parameter EVGEN:Process [string]: e-p
+ parameter EVGEN:ID1 [int]: 11
+ parameter EVGEN:ID2 [int]: 2212
+ parameter EVGEN:ProcessID [int]: 10
+ parameter EVGEN:DIS:Q2 [float]: 12.4407      // Truth-level Q^2
+ parameter EVGEN:DIS:W [float]: 69.6586       // Truth-level W
+ parameter EVGEN:DIS:XBJ [float]: 0.00255778  // Truth_level x_bjorken
+ parameter EVGEN:DIS:YBJ [float]: 0.243193    // Truth_level y_bjorken
+</code>
+Note that SLCIO files have two records representing truth level MC: MCParticle and MCInfo. MCInfo includes information on generated events.
+See the example how this record was created in [[https://github.com/Argonne-National-Laboratory/ProMC/blob/master/examples/promc2lcio/promc2lcio.java|promc2lcio.java]]
  --- //[[[email protected]|Sergei Chekanov]] 2016/09/19 07:06//