RichMCOpticalPhotonUtils: New accessor for MC photons associated to a given MCParticle

Rich/RichFutureMCUtils/include/RichFutureMCUtils/RichMCOpticalPhotonUtils.h

@@ -15,6 +15,8 @@
 #include "Kernel/RichSmartID.h"
 
 // Event model
+#include "Event/MCParticle.h"
+#include "Event/MCRichHit.h"
 #include "Event/MCRichOpticalPhoton.h"
 
 // Rich Utils
@@ -61,31 +63,46 @@ namespace Rich::Future::MC::Relations {
       // Get the list of all MC photons associated to the hits
       auto mcPhots = mcOpticalPhotons( hits );
       // filter out those not linked to mcPs
-      const auto it = std::remove_if( mcPhots.begin(), mcPhots.end(), //
-                                      [&mcPs]( auto&& phot ) {
-                                        // Get the MCParticle associated to this photon
-                                        const auto mcP =
-                                            ( phot && phot->mcRichHit() ? phot->mcRichHit()->mcParticle() : nullptr );
-                                        // if MCP not in supplied list return true to erase
-                                        return ( !mcP || std::find( mcPs.begin(), mcPs.end(), mcP ) == mcPs.end() );
-                                      } );
+      const auto it =                                     //
+          std::remove_if( mcPhots.begin(), mcPhots.end(), //
+                          [&mcPs]( auto&& phot ) {
+                            // Get the MCParticle associated to this photon
+                            const auto mcH = ( phot ? phot->mcRichHit() : nullptr );
+                            const auto mcP = ( mcH ? mcH->mcParticle() : nullptr );
+                            // if MCP not in supplied list return true to erase
+                            return ( !mcP || std::find( mcPs.begin(), mcPs.end(), mcP ) == mcPs.end() );
+                          } );
       // remove the entries selected for deletion
       mcPhots.erase( it, mcPhots.end() );
       // return
       return mcPhots;
     }
 
+    /// Get MCRichOpticalPhotons for a given MCParticle
+    const auto& mcOpticalPhotons( const LHCb::MCParticle* mcP ) const {
+      // Null entry for when missing
+      static LHCb::MCRichOpticalPhoton::ConstVector missing;
+      // Do we have this MCP in the map
+      const auto mcOPs = m_mcpToPhots.find( mcP );
+      // return
+      return ( mcOPs != m_mcpToPhots.end() ? mcOPs->second : missing );
+    }
+
   private:
     // types
 
     /// Type for mapping from MCRichHit to MCRichOpticalPhoton
     using MCRichHitToOpPhot = Rich::Map<const LHCb::MCRichHit*, const LHCb::MCRichOpticalPhoton*>;
+    /// Type for mapping MCParticle to MCRichOpticalPhotons
+    using MCPartToOpPhots = Rich::Map<const LHCb::MCParticle*, LHCb::MCRichOpticalPhoton::ConstVector>;
 
   private:
     // cached data
 
     /// Mapping of hits to photons
     MCRichHitToOpPhot m_hitToPhot;
+    /// Mapping of MCParticles to photons
+    MCPartToOpPhots m_mcpToPhots;
   };
 
 } // namespace Rich::Future::MC::Relations

Rich/RichFutureMCUtils/src/lib/RichMCOpticalPhotonUtils.cpp

@@ -9,15 +9,23 @@
 * or submit itself to any jurisdiction.                                       *
 \*****************************************************************************/
 
-// local
 #include "RichFutureMCUtils/RichMCOpticalPhotonUtils.h"
 
 using namespace Rich::Future::MC::Relations;
 
 MCOpticalPhotonUtils::MCOpticalPhotonUtils( const LHCb::MCRichOpticalPhotons& mcphotons ) {
-  // loop over mc photons
   for ( const auto mcphot : mcphotons ) {
-    // save hit -> phot link
-    if ( mcphot && mcphot->mcRichHit() ) { m_hitToPhot[mcphot->mcRichHit()] = mcphot; }
+    if ( mcphot ) {
+      const auto mcH = mcphot->mcRichHit();
+      if ( mcH ) {
+        m_hitToPhot[mcH] = mcphot;
+        const auto mcP   = mcH->mcParticle();
+        if ( mcP ) {
+          auto& phots = m_mcpToPhots[mcP];
+          if ( phots.empty() ) { phots.reserve( 40 ); }
+          phots.push_back( mcphot );
+        }
+      }
+    }
   }
 }