fix: Particle selector works on measurements, not simhits

Examples/Algorithms/TruthTracking/ActsExamples/TruthTracking/ParticleSelector.cpp

@@ -28,6 +28,12 @@ ActsExamples::ParticleSelector::ParticleSelector(const Config& config,
   }
 
   m_inputParticles.initialize(m_cfg.inputParticles);
+
+  Config defaults;
+  if (m_cfg.measurementsMin > defaults.measurementsMin ||
+      m_cfg.measurementsMax < defaults.measurementsMax) {
+    m_inputMeasPartMap.initialize(m_cfg.inputMeasurementParticlesMap);
+  }
   m_outputParticles.initialize(m_cfg.outputParticles);
 
   ACTS_DEBUG("selection particle rho [" << m_cfg.rhoMin << "," << m_cfg.rhoMax
@@ -56,6 +62,21 @@ ActsExamples::ProcessCode ActsExamples::ParticleSelector::execute(
   // prepare input/ output types
   const SimParticleContainer& inputParticles = m_inputParticles(ctx);
 
+  // Optionally construct a particles->measurement map
+  std::optional<boost::container::flat_multimap<ActsFatras::Barcode, Index>>
+      partMeasMap;
+  if (m_inputMeasPartMap.isInitialized()) {
+    const auto& measPartMap = m_inputMeasPartMap(ctx);
+    using InvPair = std::pair<ActsFatras::Barcode, Index>;
+    std::vector<InvPair> v(measPartMap.size());
+    std::ranges::transform(measPartMap, v.begin(), [](const auto& p) {
+      return InvPair{p.second, p.first};
+    });
+    std::ranges::sort(v, std::less{}, &InvPair::first);
+    partMeasMap.emplace(boost::container::ordered_range_t{}, v.begin(),
+                        v.end());
+  }
+
   std::size_t nInvalidCharge = 0;
   std::size_t nInvalidMeasurementCount = 0;
 
@@ -76,8 +97,13 @@ ActsExamples::ProcessCode ActsExamples::ParticleSelector::execute(
 
     nInvalidCharge += static_cast<std::size_t>(!validCharge);
 
-    bool validMeasurementCount =
-        within(p.numberOfHits(), m_cfg.measurementsMin, m_cfg.measurementsMax);
+    bool validMeasurementCount = true;
+    if (partMeasMap) {
+      auto [begin, end] = partMeasMap->equal_range(p.particleId());
+      std::size_t nMeasurements = std::distance(begin, end);
+      validMeasurementCount =
+          within(nMeasurements, m_cfg.measurementsMin, m_cfg.measurementsMax);
+    }
 
     nInvalidMeasurementCount +=
         static_cast<std::size_t>(!validMeasurementCount);

Examples/Algorithms/TruthTracking/ActsExamples/TruthTracking/ParticleSelector.hpp

@@ -9,6 +9,7 @@
 #pragma once
 
 #include "Acts/Utilities/Logger.hpp"
+#include "ActsExamples/EventData/Index.hpp"
 #include "ActsExamples/EventData/SimParticle.hpp"
 #include "ActsExamples/Framework/DataHandle.hpp"
 #include "ActsExamples/Framework/IAlgorithm.hpp"
@@ -26,6 +27,9 @@ class ParticleSelector final : public IAlgorithm {
   struct Config {
     /// The input particles collection.
     std::string inputParticles;
+    /// The input measurement particles map (optional, required if selection
+    /// based on number of measurements is requested).
+    std::string inputMeasurementParticlesMap;
     /// The output particles collection.
     std::string outputParticles;
 
@@ -75,6 +79,8 @@ class ParticleSelector final : public IAlgorithm {
   Config m_cfg;
 
   ReadDataHandle<SimParticleContainer> m_inputParticles{this, "InputParticles"};
+  ReadDataHandle<IndexMultimap<ActsFatras::Barcode>> m_inputMeasPartMap{
+      this, "InputMeasPartMap"};
 
   WriteDataHandle<SimParticleContainer> m_outputParticles{this,
                                                           "OutputParticles"};

Examples/Framework/include/ActsExamples/EventData/SimParticle.hpp

@@ -161,8 +161,8 @@ class SimParticle final {
   /// Accumulated path within material measured in interaction lengths.
   double pathInL0() const { return final().pathInL0(); }
 
-  /// Number of hits.
-  std::uint32_t numberOfHits() const { return final().numberOfHits(); }
+  /// Number of simulated hits (not measurements).
+  std::uint32_t numberOfSimHits() const { return final().numberOfHits(); }
 
   /// Particle outcome.
   ActsFatras::ParticleOutcome outcome() const { return final().outcome(); }

Examples/Io/Json/src/TestSurfaceJsonRoundtrip.cpp

@@ -0,0 +1,37 @@
+// This file is part of the ACTS project.
+//
+// Copyright (C) 2016 CERN for the benefit of the ACTS project
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+#include "ActsExamples/Io/Json/JsonSurfacesReader.hpp"
+#include <Acts/Plugins/Json/SurfaceJsonConverter.hpp>
+
+#include <fstream>
+
+#include <nlohmann/json.hpp>
+
+void writeSurfaces(
+    std::ostream &os,
+    const std::vector<std::shared_ptr<Acts::Surface>> &jSurfaces) {
+  nlohmann::json j = nlohmann::json::array();
+
+  for (const auto &jSurface : jSurfaces) {
+    j.push_back(
+        Acts::SurfaceJsonConverter::toJson(Acts::GeometryContext{}, *jSurface));
+  }
+
+  os << j;
+}
+
+int main(int argc, char **argv) {
+  std::vector<std::string> args(argv, argv + argc);
+
+  auto surfaces =
+      ActsExamples::JsonSurfacesReader::readVector({args.at(1), {}});
+
+  std::ofstream outfile("output_surfaces.json");
+  writeSurfaces(outfile, surfaces);
+}

Examples/Io/Root/src/RootParticleWriter.cpp

@@ -143,7 +143,7 @@ ActsExamples::ProcessCode ActsExamples::RootParticleWriter::writeT(
         Acts::clampValue<float>(particle.pathInX0() / Acts::UnitConstants::mm));
     m_pathInL0.push_back(
         Acts::clampValue<float>(particle.pathInL0() / Acts::UnitConstants::mm));
-    m_numberOfHits.push_back(particle.numberOfHits());
+    m_numberOfHits.push_back(particle.numberOfSimHits());
     m_outcome.push_back(static_cast<std::uint32_t>(particle.outcome()));
   }
 

Examples/Python/python/acts/examples/simulation.py

@@ -356,6 +356,7 @@ def addParticleSelection(
     config: ParticleSelectorConfig,
     inputParticles: str,
     outputParticles: str,
+    inputMeasurementParticlesMap: str = "",
     logLevel: Optional[acts.logging.Level] = None,
 ) -> None:
     """
@@ -401,6 +402,7 @@ def addParticleSelection(
             ),
             level=customLogLevel(),
             inputParticles=inputParticles,
+            inputMeasurementParticlesMap=inputMeasurementParticlesMap,
             outputParticles=outputParticles,
         )
     )

Examples/Python/src/TruthTracking.cpp

@@ -62,6 +62,7 @@ void addTruthTracking(Context& ctx) {
 
     ACTS_PYTHON_STRUCT_BEGIN(c, Config);
     ACTS_PYTHON_MEMBER(inputParticles);
+    ACTS_PYTHON_MEMBER(inputMeasurementParticlesMap);
     ACTS_PYTHON_MEMBER(outputParticles);
     ACTS_PYTHON_MEMBER(rhoMin);
     ACTS_PYTHON_MEMBER(rhoMax);