feat: Bindings for Spacepoints, Seeds and TrackContainer (#5242)

Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

Author: paulgessinger

Core/include/Acts/EventData/TrackProxy.hpp

@@ -255,6 +255,7 @@ class TrackProxy
   using Base::chi2;
   using Base::direction;
   using Base::fourMomentum;
+  using Base::isForwardLinked;
   using Base::loc0;
   using Base::loc1;
   using Base::momentum;

Core/include/Acts/EventData/TrackProxyCommon.hpp

@@ -10,6 +10,7 @@
 
 #include "Acts/Definitions/Common.hpp"
 #include "Acts/Definitions/TrackParametrization.hpp"
+#include "Acts/EventData/Types.hpp"
 #include "Acts/Utilities/HashedString.hpp"
 
 namespace Acts {
@@ -77,6 +78,12 @@ class TrackProxyCommon {
     return derived().template component<IndexType, detail_tp::kStemIndexKey>();
   }
 
+  /// Return whether the track is forward-linked, i.e. whether each track state
+  /// has a valid next-state index. Forward-linking is required to use the
+  /// inside-out @c trackStates() range.
+  /// @return True if the track is forward-linked
+  bool isForwardLinked() const { return stemIndex() != kTrackIndexInvalid; }
+
   /// Return the number of measurements assigned to this track.
   /// @return The number of measurements
   unsigned int nMeasurements() const {

Core/include/Acts/TrackFinding/TrackSelector.hpp

@@ -438,8 +438,7 @@ void TrackSelector::selectTracks(const input_tracks_t& inputTracks,
       continue;
     }
     auto destProxy = outputTracks.makeTrack();
-    destProxy.copyFromWithoutStates(track);
-    destProxy.tipIndex() = track.tipIndex();
+    destProxy.copyFromShallow(track);
   }
 }
 

Examples/Algorithms/TrackFitting/include/ActsExamples/TrackFitting/TrackFittingAlgorithm.hpp

@@ -46,6 +46,9 @@ class TrackFittingAlgorithm final : public IAlgorithm {
     int pickTrack = -1;
     // Type erased calibrator for the measurements
     std::shared_ptr<MeasurementCalibrator> calibrator;
+    /// Forward-link all tracks after fitting, enabling inside-out track state
+    /// iteration via TrackProxy::trackStates(). Off by default.
+    bool linkForward = false;
   };
 
   /// Constructor of the fitting algorithm

Examples/Algorithms/TrackFitting/src/TrackFittingAlgorithm.cpp

@@ -174,6 +174,12 @@ ProcessCode TrackFittingAlgorithm::execute(const AlgorithmContext& ctx) const {
 
   ACTS_DEBUG("Fitted tracks: " << trackContainer->size());
 
+  if (m_cfg.linkForward) {
+    for (auto track : tracks) {
+      track.linkForward();
+    }
+  }
+
   if (logger().doPrint(Acts::Logging::DEBUG)) {
     std::stringstream ss;
     trackStateContainer->statistics().toStream(ss);

Examples/Scripts/Python/truth_tracking_kalman.py

@@ -20,6 +20,8 @@ def runTruthTrackingKalman(
     generatedParticleType: acts.PdgParticle = acts.PdgParticle.eMuon,
     reverseFilteringMomThreshold=0 * u.GeV,
     reverseFilteringCovarianceScaling=100.0,
+    numParticles=1,
+    linkForward: bool = False,
     s: acts.examples.Sequencer = None,
 ):
     from acts.examples.simulation import (
@@ -64,7 +66,9 @@ def runTruthTrackingKalman(
     if inputParticlePath is None:
         addParticleGun(
             s,
-            ParticleConfig(num=1, pdg=generatedParticleType, randomizeCharge=True),
+            ParticleConfig(
+                num=numParticles, pdg=generatedParticleType, randomizeCharge=True
+            ),
             EtaConfig(-3.0, 3.0, uniform=True),
             MomentumConfig(1.0 * u.GeV, 100.0 * u.GeV, transverse=True),
             PhiConfig(0.0, 360.0 * u.degree),
@@ -165,6 +169,7 @@ def runTruthTrackingKalman(
         field,
         reverseFilteringMomThreshold,
         reverseFilteringCovarianceScaling,
+        linkForward=linkForward,
     )
 
     s.addAlgorithm(

Python/Core/CMakeLists.txt

@@ -11,6 +11,7 @@ target_sources(
     ActsPythonBindings
     PRIVATE
         src/Definitions.cpp
+        src/EventData.cpp
         src/Utilities.cpp
         src/MagneticField.cpp
         src/Material.cpp

Python/Core/src/CoreModuleEntry.cpp

@@ -19,6 +19,7 @@ namespace py = pybind11;
 namespace ActsPython {
 
 void addDefinitions(py::module_& m);
+void addEventData(py::module_& m);
 void addMagneticField(py::module_& m);
 void addUtilities(py::module_& m);
 void addVisualization(py::module_& m);
@@ -64,6 +65,7 @@ PYBIND11_MODULE(ActsPythonBindings, m) {
 
   addSurfaces(m);
   addGeometry(m);
+  addEventData(m);
   addGeometryGen1(m);
   addGeometryGen3(m);
   addNavigation(m);

Python/Core/src/Definitions.cpp

@@ -8,6 +8,7 @@
 
 #include "Acts/Definitions/Algebra.hpp"
 #include "Acts/Definitions/PdgParticle.hpp"
+#include "Acts/Definitions/TrackParametrization.hpp"
 #include "Acts/Definitions/Units.hpp"
 #include "Acts/EventData/ParticleHypothesis.hpp"
 
@@ -99,6 +100,40 @@ void addDefinitions(py::module_& m) {
                            self[3]);
       });
 
+  py::class_<BoundVector>(m, "BoundVector")
+      .def(py::init<double, double, double, double, double, double>())
+      .def(py::init([](std::array<double, 6> a) {
+        BoundVector v;
+        v << a[0], a[1], a[2], a[3], a[4], a[5];
+        return v;
+      }))
+      .def_static("Zero", []() -> BoundVector { return BoundVector::Zero(); })
+      .def("__getitem__",
+           [](const BoundVector& self, Eigen::Index i) { return self[i]; })
+      .def("__str__", [](const BoundVector& self) {
+        return std::format("({}, {}, {}, {}, {}, {})", self[0], self[1],
+                           self[2], self[3], self[4], self[5]);
+      });
+
+  py::class_<BoundMatrix>(m, "BoundMatrix")
+      .def(py::init([]() { return BoundMatrix::Zero(); }))
+      .def_static("Zero", []() -> BoundMatrix { return BoundMatrix::Zero(); })
+      .def_static("Identity",
+                  []() -> BoundMatrix { return BoundMatrix::Identity(); })
+      .def("__getitem__",
+           [](const BoundMatrix& self, py::object idx) {
+             py::tuple t = idx.cast<py::tuple>();
+             if (py::len(t) != 2) {
+               throw py::index_error("BoundMatrix index must be (i, j)");
+             }
+             return self(t[0].cast<Eigen::Index>(), t[1].cast<Eigen::Index>());
+           })
+      .def("__str__", [](const BoundMatrix& self) {
+        std::stringstream ss;
+        ss << self;
+        return ss.str();
+      });
+
   py::class_<Translation3>(m, "Translation3")
       .def(py::init([](const Vector3& a) { return Translation3(a); }))
       .def(py::init([](std::array<double, 3> a) {