feat: Use RootTracksummaryWriter without truth information (#3886)

Since some people start to do tests within the examples framework with real data, we should extend our algorithms/writers to not require these information. This PR does the relevant changes for the `RootTracksummaryWriter`.

Examples/Io/Root/include/ActsExamples/Io/Root/RootTrackSummaryWriter.hpp

@@ -49,9 +49,9 @@ class RootTrackSummaryWriter final : public WriterT<ConstTrackContainer> {
   struct Config {
     /// Input (fitted) tracks collection
     std::string inputTracks;
-    /// Input particles collection.
+    /// Input particles collection (optional).
     std::string inputParticles;
-    /// Input track-particle matching.
+    /// Input track-particle matching (optional).
     std::string inputTrackParticleMatching;
     /// Output filename.
     std::string filePath = "tracksummary.root";

Examples/Io/Root/src/RootTrackSummaryWriter.cpp

@@ -53,21 +53,16 @@ RootTrackSummaryWriter::RootTrackSummaryWriter(
     : WriterT(config.inputTracks, "RootTrackSummaryWriter", level),
       m_cfg(config) {
   // tracks collection name is already checked by base ctor
-  if (m_cfg.inputParticles.empty()) {
-    throw std::invalid_argument("Missing particles input collection");
-  }
-  if (m_cfg.inputTrackParticleMatching.empty()) {
-    throw std::invalid_argument("Missing input track particles matching");
-  }
   if (m_cfg.filePath.empty()) {
     throw std::invalid_argument("Missing output filename");
   }
   if (m_cfg.treeName.empty()) {
     throw std::invalid_argument("Missing tree name");
   }
 
-  m_inputParticles.initialize(m_cfg.inputParticles);
-  m_inputTrackParticleMatching.initialize(m_cfg.inputTrackParticleMatching);
+  m_inputParticles.maybeInitialize(m_cfg.inputParticles);
+  m_inputTrackParticleMatching.maybeInitialize(
+      m_cfg.inputTrackParticleMatching);
 
   // Setup ROOT I/O
   auto path = m_cfg.filePath;
@@ -220,9 +215,16 @@ ProcessCode RootTrackSummaryWriter::finalize() {
 
 ProcessCode RootTrackSummaryWriter::writeT(const AlgorithmContext& ctx,
                                            const ConstTrackContainer& tracks) {
-  // Read additional input collections
-  const auto& particles = m_inputParticles(ctx);
-  const auto& trackParticleMatching = m_inputTrackParticleMatching(ctx);
+  // In case we do not have truth info, we bind to a empty collection
+  const static SimParticleContainer emptyParticles;
+  const static TrackParticleMatching emptyTrackParticleMatching;
+
+  const auto& particles =
+      m_inputParticles.isInitialized() ? m_inputParticles(ctx) : emptyParticles;
+  const auto& trackParticleMatching =
+      m_inputTrackParticleMatching.isInitialized()
+          ? m_inputTrackParticleMatching(ctx)
+          : emptyTrackParticleMatching;
 
   // For each particle within a track, how many hits did it contribute
   std::vector<ParticleHitCount> particleHitCounts;
@@ -244,6 +246,7 @@ ProcessCode RootTrackSummaryWriter::writeT(const AlgorithmContext& ctx,
     m_nSharedHits.push_back(track.nSharedHits());
     m_chi2Sum.push_back(track.chi2());
     m_NDF.push_back(track.nDoF());
+
     {
       std::vector<double> measurementChi2;
       std::vector<std::uint32_t> measurementVolume;
@@ -266,8 +269,6 @@ ProcessCode RootTrackSummaryWriter::writeT(const AlgorithmContext& ctx,
           measurementLayer.push_back(layer);
         }
       }
-      // IDs are stored as double (as the vector of vector of int is not known
-      // to ROOT)
       m_measurementChi2.push_back(std::move(measurementChi2));
       m_measurementVolume.push_back(std::move(measurementVolume));
       m_measurementLayer.push_back(std::move(measurementLayer));

Examples/Python/tests/test_writer.py

@@ -197,6 +197,43 @@ def test_root_simhits_writer(tmp_path, fatras, conf_const, assert_root_hash):
     assert_root_hash(out.name, out)
 
 
+@pytest.mark.root
+def test_root_tracksummary_writer(tmp_path, fatras, conf_const):
+    detector, trackingGeometry, decorators = GenericDetector.create()
+    field = acts.ConstantBField(acts.Vector3(0, 0, 2 * u.T))
+    s = Sequencer(numThreads=1, events=10)
+
+    from truth_tracking_kalman import runTruthTrackingKalman
+
+    # This also runs the RootTrackSummaryWriter with truth information
+    runTruthTrackingKalman(
+        trackingGeometry,
+        field,
+        digiConfigFile=Path(
+            str(
+                Path(__file__).parent.parent.parent.parent
+                / "Examples/Algorithms/Digitization/share/default-smearing-config-generic.json"
+            )
+        ),
+        outputDir=tmp_path,
+        s=s,
+    )
+
+    # Run the RootTrackSummaryWriter without the truth information
+    s.addWriter(
+        conf_const(
+            RootTrackSummaryWriter,
+            level=acts.logging.INFO,
+            inputTracks="tracks",
+            filePath=str(tmp_path / "track_summary_kf_no_truth.root"),
+        )
+    )
+
+    s.run()
+    assert (tmp_path / "tracksummary_kf.root").exists()
+    assert (tmp_path / "track_summary_kf_no_truth.root").exists()
+
+
 @pytest.mark.csv
 def test_csv_meas_writer(tmp_path, fatras, trk_geo, conf_const):
     s = Sequencer(numThreads=1, events=10)