xAOD::TruthHelpers Namespace Reference

Dedicated namespace for the helper functions. More...

Functions
const xAOD::TruthParticle *	getTruthParticle (const xAOD::IParticle &p)
	Return the truthParticle associated to the given IParticle (if any)
const xAOD::TruthParticle *	getFinalCopy (const xAOD::TruthParticle &particle)
	Return the final copy of the truth particle (or same particle if no copies done)
int	getParticleTruthType (const xAOD::IParticle &p)
	Return the particle's truth type (as defined by the MC Truth Classifier)
int	getParticleTruthOrigin (const xAOD::IParticle &p)
	Return the particle's truth origin (as defined by the MC Truth Classifier)

Detailed Description

Dedicated namespace for the helper functions.

Function Documentation

getFinalCopy()

const TruthParticle * xAOD::TruthHelpers::getFinalCopy

(

const xAOD::TruthParticle &

particle

)

Return the final copy of the truth particle (or same particle if no copies done)

Parameters

particle

The truth particle we want to get the final copy of

Returns

A pointer to the final truth particle copy if available, or pointer to the same particle if no copies done.

Definition at line 69 of file xAODTruthHelpers.cxx.

                                                                                 {
 
         // Loop over the children
         for( size_t i{}; i < particle.nChildren(); ++i ) {
 
            // Check if particle pointer exists and it is the same particle (same PDG ID)
            if( particle.child( i ) != nullptr && particle.child( i )->pdgId() == particle.pdgId() ) {
               // Recursively check again
               // It is fine to return when we find first copy candidate as there can only be one
               return getFinalCopy( *particle.child( i ) );
            }
         }
 
         // Return the same particle if no copies found
         return &particle;
      }

getParticleTruthOrigin()

int xAOD::TruthHelpers::getParticleTruthOrigin

(

const xAOD::IParticle &

p

)

Return the particle's truth origin (as defined by the MC Truth Classifier)

Parameters

p	The particle that we want to find the truth origin of

Returns

0 if the truth origin is not available, or the truth origin determined by MCTruthClassifier, if it is

A static accessor for the information

Definition at line 109 of file xAODTruthHelpers.cxx.

                                                           {

         static const SG::AuxElement::ConstAccessor< int > acc( "truthOrigin" );
 
         // Check if such a variable exists on the object:
         if( ! acc.isAvailable( p ) ) {
            return 0;
         }
 
         // Let's return the value:
         return acc( p );
      }

getParticleTruthType()

int xAOD::TruthHelpers::getParticleTruthType

(

const xAOD::IParticle &

p

)

Return the particle's truth type (as defined by the MC Truth Classifier)

Parameters

p	The particle that we want to find the truth type of

Returns

0 if the truth type is not available, or the truth type determined by MCTruthClassifier, if it is

A static accessor for the information

Definition at line 91 of file xAODTruthHelpers.cxx.

                                                         {

         static const SG::AuxElement::ConstAccessor< int > acc( "truthType" );
 
         // Check if such a variable exists on the object:
         if( ! acc.isAvailable( p ) ) {
            return 0;
         }
 
         // Let's return the value:
         return acc( p );
      }

getTruthParticle()

const TruthParticle * xAOD::TruthHelpers::getTruthParticle

(

const xAOD::IParticle &

p

)

Return the truthParticle associated to the given IParticle (if any)

Parameters

p	The particle that we find the associated truth particle for

Returns

A pointer to the associated truth particle if available, or a null pointer if not

A convenience type declaration

A static accessor for the information

Alternative name - this may work in case of TRUTH3 / small truth collections

Definition at line 25 of file xAODTruthHelpers.cxx.

                                                                          {

         using Link_t = ElementLink<xAOD::TruthParticleContainer>;

         static const SG::AuxElement::ConstAccessor< Link_t > acc( "truthParticleLink" );
 
         // Check if such a link exists on the object:
         if( acc.isAvailable( p ) ) {
            // Get the link:
            const Link_t& link = acc( p );
 
            // Check if the link is valid:
            if( link.isValid() ) {
               // Everything has passed, let's return the pointer:
               return *link;
            }
         }

         static const SG::AuxElement::ConstAccessor< Link_t > acc_alt( "TruthLink" );
 
         // Check if such a link exists on the object:
         if( acc_alt.isAvailable( p ) ) {
            // Get the link:
            const Link_t& link_alt = acc_alt( p );
 
            // Check if the link is valid:
            if( link_alt.isValid() ) {
               // Everything has passed, let's return the pointer:
               return *link_alt;
            }
         }
 
         // Everything has failed, nothing to return
         return nullptr;
      }