EDM4hep ROOT Input

This page covers the additional setup needed to read EDM4hep ROOT files directly.

For the default HDF5 workflow, see Getting started.

Key4hep environment

The ROOT reader depends on podio and edm4hep, so it must run inside a Key4hep environment.

Create a local virtual environment from the Key4hep Python:

source /cvmfs/sw.hsf.org/key4hep/setup.sh
bash scripts/setup_key4hep_venv.sh
source /cvmfs/sw.hsf.org/key4hep/setup.sh
source .venv-key4hep/bin/activate

This matters because a regular virtual environment created before sourcing Key4hep will not see the right ROOT-stack Python packages.

The helper script installs step2point in editable mode with the dev extras into .venv-key4hep.

Run the ROOT integration test:

pytest -q tests/integration/test_root_reader_optional.py

Minimal ROOT-reader example

from step2point.io import EDM4hepRootReader

reader = EDM4hepRootReader(
    "tests/data/ODD_gamma_10ev_theta90deg_phi0deg_posX0mmY1250mmZ0mm_10GeV_edm4hep.root",
    collections=(
        "ECalBarrelCollection",
        "ECalEndcapCollection",
        "HCalBarrelCollection",
        "HCalEndcapCollection",
    ),
    shower_limit=1,
)

shower = next(reader.iter_showers())
print(shower.n_points, shower.cell_id is not None, shower.t is not None)

ROOT inspection example

python examples/inspect_showers.py \
  --input tests/data/ODD_gamma_10ev_theta90deg_phi0deg_posX0mmY1250mmZ0mm_10GeV_edm4hep.root \
  --collections ECalBarrelCollection ECalEndcapCollection HCalBarrelCollection HCalEndcapCollection \
  --shower-index 5 \
  --axis 0 1 0 \
  --outdir outputs/inspect_root