Exercise linked to printing and Job options lesson

The purpose of this exercise is to make you familiar with using job options to configure algorithms, and with the methods for printing from within a Gaudi application.

1. Setting up the environment

We will be working in the same environment as the DaVinci tutorial.

• Choose the DaVinci environment
DaVinciEnv v17r5
• Check out and configure the Tutorial package
cd ~/cmtuser getpack Tutorial/Analysis v6r1 ;  cd Tutorial/Analysis/v6r1 This package contains a requirements file already set up for the tutorial, a set of solutions for the DaVinci tutorial sessions, and empty src and options directories

2. Creating a DaVinci algorithm, adding a property and printing its value

• Create a new header file using emacs
emacs src/TutorialAlgorithm.h & We will be working with DaVinci, so you should answer "D" to emacs, this creates a header file for a DVAlgorithm
• Add a member variable to store the property
double m_jPsiMassWin;
• Create the corresponding .cpp file
emacs src/TutorialAlgorithm.cpp &
• declare a name for the property and initialize it to a default value
declareProperty( "MassWindow", <memberVariable> = <defaultValue>);
• print the property's value twice, using two different units
info() << "Mass window is " << value << " Units" << endmsg;
• Save both files and build a library with them

3. Setting up the job options and running the job

• Create a job options file
emacs options/myJob.opts
• Add the default DaVinci configuration
#include "$DAVINCIROOT/options/DaVinciCommon.opts"
• Add your library and your algorithm
ApplicationMgr.DLLs += {...}; ApplicationMgr.TopAlg += {...};
• Do not forget to define "some" input data: #include "$DAVINCITUTORIALDATA"
• Save the file and run the job. Don't forget to set the environment by sourcing setup.csh
DaVinci $ANALYSISROOT/options/myJob.opts

 

4. Modify the job behaviour by changing job options

Rerun the job after each of the following modifications. No need to recompile unless you change the .cpp!

• Reduce the amount of job options printout by putting the following lines in the appropriate places
#pragma print off #pragma print on
• Modify the value of the algorithm's property
<MyAlg>.MassWindow = 1.2*GeV;
• Change the global output level of the application
MessageSvc.OutputLevel = 2; Try any values between 1 and 5
• Change the output level of your algorithm
<MyAlg>.OutputLevel = 2; Try any values between 1 and 5
• Run two instances of your algorithm, with different values for the cut. Hint: the TopAlg property has the following format:
ApplicationMgr.TopAlg += { "<class name>/<instance name>" };

• 5.  Get the data and use histograms and N-tuples

  Add simple histograms into your algorithms 
  • Get MCParticles from their standard location: const LHCb::MCParticle::Container* mcps = get<LHCb::MCParticle::Container>( LHCb::MCParticleLocation::Default ) ;
  • Loop over MC-particles: for ( LHCb::MCParticle::Container::const_iterator imc = mcps->begin(); mcps->end() != imc ; ++imc ) { ... }
  • Fill some simple histograms :  plot ( <value> , "some value" , 0 , 10 , 100 ) ; 
  • The class methods/attribites could be inspected either via Doxigen or by code inspection:  > less  $MCEVENTROOT/Event/MCParticle.h
  • Code could be in general located using Lbglimpse script ( from /software/lhcb/scripts area) > Lbglimpse LHCb::MCParticle
  • Run algorithm, use Root or Hbook to check the histograms ApplicationMgr.TopAlg += { "<class name>/<instance name>" };
  • Add simple N-tuple into the algorithm: Tuple tuple = nTuple( "some unique title" ) ;
  • Fill few (3-4 simple columns) inside the loop tuple->column("px",mc->momentum().Px());  ...  ; tuple->write() ;
  • Run algorithm,  take care about output file: NTupleSvc.Output = { "FILE1 DATAFILE='Myfile.root' TYPE='ROOT' OPT='NEW'" } ;
  • Hints on the histograms: > less $GAUDIEXAMPLESROOT/src/Histograms/GaudiHistoAlgorithm.cpp
  • Hnts  on N-tuples: > less $GAUDIEXAMPLESROOT/src/TupleEx/TupleAlg{2}.cpp
  •  How to get $GAUDIEXAMPLESROOT ? Use Lbglimpse or just add the line into cmt/requirements file:  use GaudiExamples v*

   

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Last modified by Vanya BELYAEV, 28-Nov-06