From 8be97d9b384f31d389b0ecf6cf89c44d47eeebc5 Mon Sep 17 00:00:00 2001
From: Wouter Deconinck <wdconinc@gmail.com>
Date: Fri, 5 Aug 2022 19:03:32 +0000
Subject: [PATCH 1/2] feat: ScatteredElectronFinder, returns subset collection
 with first status==1 electron

---
 .../components/ScatteredElectronFinder.cpp    | 72 +++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 JugFast/src/components/ScatteredElectronFinder.cpp

diff --git a/JugFast/src/components/ScatteredElectronFinder.cpp b/JugFast/src/components/ScatteredElectronFinder.cpp
new file mode 100644
index 00000000..40f3054b
--- /dev/null
+++ b/JugFast/src/components/ScatteredElectronFinder.cpp
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+// Copyright (C) 2022 Wouter Deconinck
+
+#include "Gaudi/Algorithm.h"
+#include "GaudiAlg/GaudiTool.h"
+#include "GaudiAlg/Producer.h"
+#include "GaudiAlg/Transformer.h"
+#include "GaudiKernel/RndmGenerators.h"
+#include "GaudiKernel/PhysicalConstants.h"
+#include <algorithm>
+#include <cmath>
+
+#include "JugBase/IParticleSvc.h"
+#include "JugBase/DataHandle.h"
+
+#include "JugBase/Utilities/Beam.h"
+
+#include "Math/Vector4D.h"
+using ROOT::Math::PxPyPzEVector;
+
+// Event Model related classes
+#include "edm4hep/MCParticleCollection.h"
+
+namespace Jug::Fast {
+
+class ScatteredElectronFinder : public GaudiAlgorithm {
+private:
+  DataHandle<edm4hep::MCParticleCollection> m_inputMCParticleCollection{
+    "inputMCParticles",
+    Gaudi::DataHandle::Reader,
+    this};
+  DataHandle<edm4hep::MCParticleCollection> m_outputMCScatteredElectron{
+    "outputMCScatteredElectron",
+    Gaudi::DataHandle::Writer,
+    this};
+
+public:
+  ScatteredElectronFinder(const std::string& name, ISvcLocator* svcLoc)
+      : GaudiAlgorithm(name, svcLoc) {
+    declareProperty("inputMCParticles", m_inputMCParticleCollection, "MCParticles");
+    declareProperty("outputMCScatteredElectron", m_outputMCScatteredElectron, "MCScatteredElectron");
+  }
+
+  StatusCode initialize() override {
+    m_outputMCScatteredElectron->setSubsetCollection();
+    return GaudiAlgorithm::initialize();
+  }
+
+  StatusCode execute() override {
+    // input collections
+    const auto& mcparts = *(m_inputMCParticleCollection.get());
+    // output collection
+    auto& out_electron = *(m_outputMCScatteredElectron.createAndPut());
+
+    // Determine scattered electron
+    //
+    // Currently taken as first status==1 electron in HEPMC record,
+    // which seems to be correct based on a cursory glance at the
+    // Pythia8 output. In the future, it may be better to trace back
+    // each final-state electron and see which one originates from
+    // the beam.
+    const auto ef_coll = Jug::Base::Beam::find_first_scattered_electron(mcparts);
+    out_electron.push_back(ef_coll.front());
+
+    return StatusCode::SUCCESS;
+  }
+};
+
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+DECLARE_COMPONENT(ScatteredElectronFinder)
+
+} // namespace Jug::Fast
-- 
GitLab


From bda9466ddebb78a6e5e75efc17f1a37411c01e4f Mon Sep 17 00:00:00 2001
From: Wouter Deconinck <wdconinc@gmail.com>
Date: Wed, 10 Aug 2022 22:31:28 -0500
Subject: [PATCH 2/2] fix: setSubsetCollection after createAndPut

---
 JugFast/src/components/ScatteredElectronFinder.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/JugFast/src/components/ScatteredElectronFinder.cpp b/JugFast/src/components/ScatteredElectronFinder.cpp
index 40f3054b..8ef2794e 100644
--- a/JugFast/src/components/ScatteredElectronFinder.cpp
+++ b/JugFast/src/components/ScatteredElectronFinder.cpp
@@ -42,7 +42,6 @@ public:
   }
 
   StatusCode initialize() override {
-    m_outputMCScatteredElectron->setSubsetCollection();
     return GaudiAlgorithm::initialize();
   }
 
@@ -51,6 +50,7 @@ public:
     const auto& mcparts = *(m_inputMCParticleCollection.get());
     // output collection
     auto& out_electron = *(m_outputMCScatteredElectron.createAndPut());
+    out_electron.setSubsetCollection();
 
     // Determine scattered electron
     //
-- 
GitLab