tracking::reco::PedestalCalculator Class Reference

Compute per-channel, per-sample pedestal mean and noise from a baseline run. More...

#include <PedestalCalculator.h>

Classes
struct	Accumulator

Public Member Functions
	PedestalCalculator (const std::string &name, framework::Process &process)
void	configure (framework::config::Parameters &ps) override
	Callback for the EventProcessor to configure itself from the given set of parameters.
void	analyze (const framework::Event &event) override
	Process the event and make histograms or summaries.
void	onProcessEnd () override
	Callback for the EventProcessor to take any necessary action when the processing of events finishes, such as calculating job-summary quantities.
Public Member Functions inherited from framework::Analyzer
	Analyzer (const std::string &name, Process &process)
	Class constructor.
virtual void	process (Event &event) final
	Processing an event for an Analyzer is calling analyze.
virtual void	beforeNewRun (ldmx::RunHeader &run_header) final
	Don't allow Analyzers to add parameters to the run header.
Public Member Functions inherited from framework::EventProcessor
	DECLARE_FACTORY (EventProcessor, EventProcessor *, const std::string &, Process &)
	declare that we have a factory for this class
	EventProcessor (const std::string &name, Process &process)
	Class constructor.
virtual	~EventProcessor ()=default
	Class destructor.
virtual void	onNewRun (const ldmx::RunHeader &run_header)
	Callback for the EventProcessor to take any necessary action when the run being processed changes.
virtual void	onFileOpen (EventFile &event_file)
	Callback for the EventProcessor to take any necessary action when a new event input ROOT file is opened.
virtual void	onFileClose (EventFile &event_file)
	Callback for the EventProcessor to take any necessary action when a event input ROOT file is closed.
virtual void	onProcessStart ()
	Callback for the EventProcessor to take any necessary action when the processing of events starts, such as creating histograms.
template<class T >
const T &	getCondition (const std::string &condition_name)
	Access a conditions object for the current event.
TDirectory *	getHistoDirectory ()
	Access/create a directory in the histogram file for this event processor to create histograms and analysis tuples.
void	setStorageHint (framework::StorageControl::Hint hint)
	Mark the current event as having the given storage control hint from this module_.
void	setStorageHint (framework::StorageControl::Hint hint, const std::string &purposeString)
	Mark the current event as having the given storage control hint from this module and the given purpose string.
int	getLogFrequency () const
	Get the current logging frequency from the process.
int	getRunNumber () const
	Get the run number from the process.
std::string	getName () const
	Get the processor name.
void	createHistograms (const std::vector< framework::config::Parameters > &histos)
	Internal function which is used to create histograms passed from the python configuration @parma histos vector of Parameters that configure histograms to create.

Private Member Functions
void	writePedestalsJson ()
	Write the accumulated pedestals to a JSON file (output_file_).

Private Attributes
std::string	input_collection_ {"TrackerRawData"}
std::string	input_pass_name_ {""}
std::string	output_file_ {"pedestals.json"}
std::string	output_format_ {"json"}
	Storage backend for the pedestals ("json"; future: "sqlite", ...).
std::unordered_map< std::string, Accumulator >	accumulators_
long	n_events_ {0}

Additional Inherited Members
Protected Member Functions inherited from framework::EventProcessor
void	abortEvent ()
	Abort the event immediately.
Protected Attributes inherited from framework::EventProcessor
HistogramPool	histograms_
	helper object for making and filling histograms
NtupleManager &	ntuple_ {NtupleManager::getInstance()}
	Manager for any ntuples.
logging::logger	the_log_
	The logger for this EventProcessor.

Detailed Description

Compute per-channel, per-sample pedestal mean and noise from a baseline run.

Accumulates ADC values from every RawSiStripHit across all events, then on process end writes a JSON file containing the mean and RMS noise for each of the three APV25 samples. Feed the resulting JSON to PedestalSubtractor when running physics reconstruction.

Definition at line 21 of file PedestalCalculator.h.

Constructor & Destructor Documentation

PedestalCalculator()

tracking::reco::PedestalCalculator::PedestalCalculator ( const std::string & name, framework::Process & process )

inline

Definition at line 23 of file PedestalCalculator.h.

      : framework::Analyzer(name, process) {}

Member Function Documentation

analyze()

void tracking::reco::PedestalCalculator::analyze ( const framework::Event & event )

overridevirtual

Process the event and make histograms or summaries.

Parameters

event

The Event to analyze

Implements framework::Analyzer.

Definition at line 20 of file PedestalCalculator.cxx.

                                                            {
  const auto& hits = event.getCollection<ldmx::RawSiStripHit>(input_collection_,
                                                              input_pass_name_);
 
  for (const auto& hit : hits) {
    const auto key = channelmap::channelKey(hit.getFebId(), hit.getHybridId(),
                                            hit.getApvId(), hit.getChannel());
    auto& acc = accumulators_[key];
    acc.n_++;
    const auto& samples = hit.getSamples();
    for (int s = 0; s < channelmap::K_SAMPLES_PER_APV_TRIGGER &&
                    s < static_cast<int>(samples.size());
         ++s) {
      // Welford's online algorithm: numerically stable incremental
      // mean+variance.
      double v = samples[s];
      double delta = v - acc.mean_[s];
      acc.mean_[s] += delta / acc.n_;
      acc.m2_[s] += delta * (v - acc.mean_[s]);
    }
  }
  ++n_events_;
}

References tracking::reco::channelmap::channelKey(), and tracking::reco::channelmap::K_SAMPLES_PER_APV_TRIGGER.

configure()

void tracking::reco::PedestalCalculator::configure ( framework::config::Parameters & parameters )

overridevirtual

Callback for the EventProcessor to configure itself from the given set of parameters.

The parameters a processor has access to are the member variables of the python class in the sequence that has class_name equal to the EventProcessor class name.

For an example, look at MyProcessor.

Parameters

parameters

Parameters for configuration.

Reimplemented from framework::EventProcessor.

Definition at line 12 of file PedestalCalculator.cxx.

                                                                {
  input_collection_ =
      ps.get<std::string>("input_collection", input_collection_);
  input_pass_name_ = ps.get<std::string>("input_pass_name", input_pass_name_);
  output_file_ = ps.get<std::string>("output_file", output_file_);
  output_format_ = ps.get<std::string>("output_format", output_format_);
}

References framework::config::Parameters::get(), and output_format_.

onProcessEnd()

void tracking::reco::PedestalCalculator::onProcessEnd ( )

overridevirtual

Callback for the EventProcessor to take any necessary action when the processing of events finishes, such as calculating job-summary quantities.

Reimplemented from framework::EventProcessor.

Definition at line 44 of file PedestalCalculator.cxx.

                                      {
  // Dispatch on the configured storage backend.  Only JSON is supported today;
  // additional backends (e.g. SQLite) can be added as new write*() methods.
  if (output_format_ == "json") {
    writePedestalsJson();
  } else {
    ldmx_log(error) << "Unknown output_format '" << output_format_
                    << "' (supported: 'json')";
  }
}

References output_format_, and writePedestalsJson().

writePedestalsJson()

void tracking::reco::PedestalCalculator::writePedestalsJson ( )

private

Write the accumulated pedestals to a JSON file (output_file_).

Definition at line 55 of file PedestalCalculator.cxx.

                                            {
  nlohmann::json channels = nlohmann::json::object();
  for (const auto& [key, acc] : accumulators_) {
    std::array<double, channelmap::K_SAMPLES_PER_APV_TRIGGER> noise{};
    for (int s = 0; s < channelmap::K_SAMPLES_PER_APV_TRIGGER; ++s) {
      // Welford: M2/(n-1) is the sample variance; M2/n is population variance.
      // Use population variance (divide by n) since we want noise of the
      // distribution.
      noise[s] = acc.n_ > 1 ? std::sqrt(acc.m2_[s] / acc.n_) : 0.0;
    }
    channels[key] = {{"mean", acc.mean_}, {"noise", noise}};
  }
 
  nlohmann::json doc = {{"n_events", n_events_}, {"channels", channels}};
 
  std::ofstream out(output_file_);
  if (!out) {
    ldmx_log(error) << "Cannot write to '" << output_file_ << "'";
    return;
  }
  out << doc.dump(2) << std::endl;
 
  ldmx_log(info) << "Wrote " << accumulators_.size() << " channels from "
                 << n_events_ << " events to '" << output_file_ << "'";
}

References tracking::reco::channelmap::K_SAMPLES_PER_APV_TRIGGER.

Referenced by onProcessEnd().

Member Data Documentation

accumulators_

std::unordered_map<std::string, Accumulator> tracking::reco::PedestalCalculator::accumulators_

private

Definition at line 49 of file PedestalCalculator.h.

input_collection_

std::string tracking::reco::PedestalCalculator::input_collection_ {"TrackerRawData"}

private

Definition at line 43 of file PedestalCalculator.h.

{"TrackerRawData"};

input_pass_name_

std::string tracking::reco::PedestalCalculator::input_pass_name_ {""}

private

Definition at line 44 of file PedestalCalculator.h.

{""};

n_events_

long tracking::reco::PedestalCalculator::n_events_ {0}

private

Definition at line 50 of file PedestalCalculator.h.

{0};

output_file_

std::string tracking::reco::PedestalCalculator::output_file_ {"pedestals.json"}

private

Definition at line 45 of file PedestalCalculator.h.

{"pedestals.json"};

output_format_

std::string tracking::reco::PedestalCalculator::output_format_ {"json"}

private

Storage backend for the pedestals ("json"; future: "sqlite", ...).

Definition at line 47 of file PedestalCalculator.h.

{"json"};

Referenced by configure(), and onProcessEnd().

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The documentation for this class was generated from the following files:

• Tracking/include/Tracking/Reco/PedestalCalculator.h
• Tracking/src/Tracking/Reco/PedestalCalculator.cxx