atlas-schema 0.4.1

Helper python package for ATLAS Common NTuple Analysis work.

atlas-schema v0.4.1

This is the python package containing schemas and helper functions enabling analyzers to work with ATLAS datasets (Monte Carlo and Data), using coffea.

Hello World

The simplest example is to just get started processing the file as expected:

from atlas_schema.schema import NtupleSchema
from coffea import dataset_tools
import awkward as ak

fileset = {"ttbar": {"files": {"path/to/ttbar.root": "tree_name"}}}
samples, report = dataset_tools.preprocess(fileset)


def noop(events):
    return ak.fields(events)


fields = dataset_tools.apply_to_fileset(noop, samples, schemaclass=NtupleSchema)
print(fields)

which produces something similar to

{
    "ttbar": [
        "dataTakingYear",
        "mcChannelNumber",
        "runNumber",
        "eventNumber",
        "lumiBlock",
        "actualInteractionsPerCrossing",
        "averageInteractionsPerCrossing",
        "truthjet",
        "PileupWeight",
        "RandomRunNumber",
        "met",
        "recojet",
        "truth",
        "generatorWeight",
        "beamSpotWeight",
        "trigPassed",
        "jvt",
    ]
}

However, a more involved example to apply a selection and fill a histogram looks like below:

import awkward as ak
from hist import Hist
import matplotlib.pyplot as plt
from coffea import processor
from distributed import Client

from atlas_schema.schema import NtupleSchema


class MyFirstProcessor(processor.ProcessorABC):
    def __init__(self):
        pass

    def process(self, events):
        dataset = events.metadata["dataset"]
        h_ph_pt = (
            Hist.new.StrCat(["all", "pass", "fail"], name="isEM")
            .Regular(200, 0.0, 2000.0, name="pt", label="$pt_{\gamma}$ [GeV]")
            .Int64()
        )

        cut = ak.all(events.ph.isEM, axis=1)
        h_ph_pt.fill(isEM="all", pt=ak.firsts(events.ph.pt / 1.0e3))
        h_ph_pt.fill(isEM="pass", pt=ak.firsts(events[cut].ph.pt / 1.0e3))
        h_ph_pt.fill(isEM="fail", pt=ak.firsts(events[~cut].ph.pt / 1.0e3))

        return {
            dataset: {
                "entries": ak.num(events, axis=0),
                "ph_pt": h_ph_pt,
            }
        }

    def postprocess(self, accumulator):
        pass


if __name__ == "__main__":
    client = Client()

    fileset = {"700352.Zqqgamma.mc20d.v1": {"files": {"ntuple.root": "analysis"}}}

    run = processor.Runner(
        executor=processor.IterativeExecutor(compression=None),
        schema=NtupleSchema,
        savemetrics=True,
    )

    out, metrics = run(fileset, processor_instance=MyFirstProcessor())

    print(out)
    print(metrics)

    fig, ax = plt.subplots()
    computed["700352.Zqqgamma.mc20d.v1"]["ph_pt"].plot1d(ax=ax)
    ax.set_xscale("log")
    ax.legend(title="Photon pT for Zqqgamma")

    fig.savefig("ph_pt.pdf")

which produces

Processing with Systematic Variations

For analyses requiring systematic uncertainty evaluation, you can easily iterate over all systematic variations using the new events["NOSYS"] alias and systematic_names property:

import awkward as ak
from hist import Hist
from coffea import processor
from atlas_schema.schema import NtupleSchema


class SystematicsProcessor(processor.ProcessorABC):
    def __init__(self):
        self.h = (
            Hist.new.StrCat([], name="variation", growth=True)
            .Regular(50, 0.0, 500.0, name="jet_pt", label="Leading Jet $p_T$ [GeV]")
            .Int64()
        )

    def process(self, events):
        dsid = events.metadata["dataset"]

        # Process all systematic variations including nominal ("NOSYS")
        for variation in events.systematic_names:
            event_view = events[variation]

            # Fill histogram with leading jet pT for this systematic variation
            leading_jet_pt = event_view.jet.pt[:, 0] / 1_000  # Convert MeV to GeV
            weights = (
                event_view.weight.mc
                if hasattr(event_view, "weight")
                else ak.ones_like(leading_jet_pt)
            )

            self.h.fill(variation=variation, jet_pt=leading_jet_pt, weight=weights)

        return {
            "hist": self.h,
            "meta": {"sumw": {dsid: {(events.metadata["fileuuid"], ak.sum(weights))}}},
        }

    def postprocess(self, accumulator):
        return accumulator

This approach allows you to seamlessly process both nominal and systematic variations in a single loop, eliminating the need for special-case handling of the nominal variation.

Developer Notes

Converting Enums from C++ to Python

This useful vim substitution helps:

%s/    \([A-Za-z]\+\)\s\+=  \(\d\+\),\?/    \1: Annotated[int, "\1"] = \2