Meta Module

The meta class reads and caches ATLAS AMI/AGIS dataset metadata from ROOT files and from a local JSON cache. It exposes all metadata fields as typed cproperty accessors so that user code can transparently read them.

Class: meta

Header: <meta/meta.h>

Inheritance: tools, notification

Public Methods

Signature	Description
const folds_t* get_tags(std::string hash)	Returns the folds_t tag struct for a given event hash.
void scan_data(TObject* obj)	Scans a ROOT TObject (typically a TTree or TH1F) for metadata leaves (run number, event number, sum-of-weights, …).
void scan_sow(TObject* obj)	Scans a ROOT object specifically for the sum-of-weights histogram.
void parse_json(std::string inpt)	Parses an AMI JSON string into meta_data.
std::string hash(std::string fname)	Returns the 18-character hash for the given filename, used as the dataset identifier.

Public Fields

Field	Type	Description
rpd	rapidjson::Document*	Parsed JSON document (nullptr until parse_json is called).
metacache_path	std::string	Path of the local JSON metadata cache directory.
meta_data	meta_t	Raw metadata struct (backing store for all cproperty accessors).

Boolean Properties

Property	Description
isMC	true if the dataset is Monte Carlo simulation.
found	true if metadata was successfully retrieved from AMI/AGIS.

Numeric Properties (double)

Property	Description
eventNumber	Reserved internal counter that maps to a ROOT-level event-number field. Populated by scan_data from the MetaData tree; default -1.
event_index	Free-parameter index used by the framework to track the current event position within a dataset; default -1.
totalSize	Total dataset size in bytes as reported by AMI ("totalSize" field).
kfactor	K-factor (higher-order QCD/EW correction scale factor) for the sample. Populated from AMI "kFactor@PMG"; defaults to 1 if absent.
ecmEnergy	Centre-of-mass collision energy in GeV (e.g. 13000.0 for 13 TeV Run 2). From AMI "ecmEnergy" field.
genFiltEff	Generator-level filter efficiency: fraction of events passing the generator filter (0–1). From AMI "genFiltEff" field.
completion	Dataset completion fraction (0–1) as reported by AMI ("completion" field).
beam_energy	Individual beam energy in GeV (half of ecmEnergy for symmetric beams). From AMI "beam_energy" field.
cross_section_nb	Inclusive production cross-section in nanobarns (nb), set from meta_t.crossSection_mean.
cross_section_pb	Cross-section converted to picobarns: cross_section_nb × 1000.
cross_section_fb	Cross-section converted to femtobarns: cross_section_nb × 10⁶.
campaign_luminosity	Integrated luminosity of the ATLAS campaign this sample belongs to (in fb⁻¹), stored in meta_t.campaign_luminosity.
sum_of_weights	Sum of MC event weights for normalisation, taken from the first weights_t entry in misc that has a non-negative processed_events_weighted value.

Numeric Properties (unsigned int)

Property	Description
dsid	ATLAS Dataset Identifier (DSID): the unique integer that identifies the MC sample in the ATLAS production system (e.g. 410470 for the standard ttbar TOPQ1 sample). Read from inputConfig.dsid in the AnalysisTracking JSON, or from the third x-axis bin of the sum-of-weights histogram.
nFiles	Number of files in the dataset as reported by AMI ("nFiles" field).
totalEvents	Total number of events in the dataset as reported by AMI ("totalEvents" field).
datasetNumber	AMI internal dataset number ("datasetNumber" field), which may differ from dsid for some derived datasets.

String Properties

Property	Description
derivationFormat	ATLAS DAOD derivation framework format used to produce the sample (e.g. "TOPQ1"). Extracted from the inputConfig.derivationFormat key of the AnalysisTracking JSON tree in the ROOT file, or from the -DCMAKE_ANALYSISG_CUDA=OFF build configuration if absent.
AMITag	AMI production tag string (e.g. "e7101_s3681_r13144_p5855"). Read from inputConfig.amiTag in the AnalysisTracking JSON; if absent, extracted from the second-to-last path component of the first input file; falls back to the second-to-last component of sample_name.
generators	Space-separated list of MC generator names read from the generators branch of the AnalysisTracking tree (e.g. "PP8" for Powheg+Pythia8). The setter strips + characters and replaces them with spaces.
identifier	AMI dataset identifier string as returned by the AMI API get_dataset_info call (maps to the "identifier" field in the AMI response).
DatasetName	Human-readable dataset name. Set to the logicalDatasetName returned by the AMI get_dataset_info call and also written into meta_t.DatasetName.
prodsysStatus	Production system status string from AMI (e.g. "done"). Maps directly to the "prodsysStatus" key in the AMI dataset-info response.
dataType	Data format type string from AMI (e.g. "DAOD"). Maps to the "dataType" key in the AMI dataset-info response.
version	Dataset version string from AMI (e.g. "001"). Maps to the "version" key in the AMI dataset-info response.
PDF	Parton Distribution Function set name used in the generator (e.g. "PDF4LHC21"). Maps to the "PDF" key in the AMI dataset-info response.
AtlasRelease	ATLAS software release tag used when producing the sample (e.g. "AthDerivation-22.2.96"). Maps to the "AtlasRelease" key in the AMI dataset-info response.
principalPhysicsGroup	ATLAS physics group responsible for the sample (e.g. "Top"). Maps to the "principalPhysicsGroup" key in the AMI response.
physicsShort	Short physics-process description label assigned by the producing group (e.g. "ttbar_Pythia8EvtGen_A14_NNPDF23_AFII"). Maps to "physicsShort" in the AMI response.
generatorName	Full generator name string from AMI (e.g. "Powheg+Pythia8"). Maps to "generatorName" in the AMI response.
geometryVersion	ATLAS detector geometry tag (e.g. "ATLAS-R3S-2021-03-02-00"). Maps to "geometryVersion" in the AMI response.
conditionsTag	ATLAS conditions database tag (e.g. "OFLCOND-MC21-SDR-RUN3-09"). Maps to "conditionsTag" in the AMI response.
generatorTune	Underlying-event tune name of the MC generator (e.g. "A14 NNPDF2.3 AFII"). Maps to "generatorTune" in the AMI response.
amiStatus	AMI dataset lifecycle status (e.g. "valid"). Maps to "amiStatus" in the AMI response.
beamType	Beam collision type (e.g. "collisions"). Maps to "beamType" in the AMI response.
productionStep	AMI production step label (e.g. "merge"). Maps to "productionStep" in the AMI response.
projectName	ATLAS MC production project name (e.g. "mc21_13p6TeV"). Maps to "projectName" in the AMI response.
statsAlgorithm	Statistical algorithm used for event counting (e.g. "EventCount"). Maps to "statsAlgorithm" in the AMI response.
genFilterNames	Comma-separated list of generator filter names applied to the sample (e.g. "ttbar_filter"). Maps to "genFilterNames" in the AMI response.
file_type	File format type string (e.g. "DAOD_TOPQ1"). Maps to "file_type" in the AMI response.
sample_name	Full sample path or name stored locally. Also used as a fallback source for AMITag when the ROOT file lacks an inputConfig.amiTag entry: the second-to-last "/"-separated component is parsed as the tag.
logicalDatasetName	Full AMI logical dataset name including all tags (e.g. "mc21_13p6TeV.410470.PhPy8EG_ttbar.deriv.DAOD_TOPQ1.e6337_…"). Maps to "logicalDatasetName" in the AMI response.
campaign	ATLAS MC production campaign identifier (e.g. "mc21a"). Extracted at scan time from the x-axis bin labels of the sum-of-weights TH1F cutflow histogram: the first bin label containing "mc" is recorded here, with spaces stripped.

Vector Properties

Property	Type	Description
keywords	std::vector<std::string>	AMI keyword list.
weights	std::vector<std::string>	Available event-weight names.
keyword	std::vector<std::string>	Short keyword list.
fileGUID	std::vector<std::string>	GUID strings for each input file.
events	std::vector<int>	Number of events per input file.
run_number	std::vector<int>	Run numbers in the dataset.
fileSize	std::vector<double>	File sizes in bytes.

Map Properties

Property	Type	Description
inputrange	std::map<int, int>	Maps run number → event count.
inputfiles	std::map<int, std::string>	Maps file index → file path.
LFN	std::map<std::string, int>	Logical File Name → file index.
misc	std::map<std::string, weights_t>	Miscellaneous weight name → weights_t struct.
config	std::map<std::string, std::string>	Arbitrary key-value configuration pairs.