pylhe 0.9.2

A small package to get structured data out of Les Houches Event files

pylhe: Python LHE interface

Small and thin Python interface to read Les Houches Event (LHE) files

Tested Monte Carlo Generators' LHE output

Generator	Tested Versions
MadGraph5	2.0.0, 2.2.1, 3.5.8
POWHEG-BOX-V2	r4027
Pythia	6.413, 8.3.14
Sherpa	3.0.1
Whizard	3.1.4

Note: test files are provided via the scikit-hep-testdata package. Please open an issue of create directly a PR for the inclusion of new files for testing.

Install

To install pylhe from PyPI you can just do

python -m pip install pylhe

The visualization capabilities require the external dependency of Graphviz.

Get started

The example below provides a simple overview. Full functionality can be inspected from the functions provided in the pylhe module.

Reading

import itertools

# You can use LHE files from scikit-hep-testdata
from skhep_testdata import data_path

import pylhe

lhe_file = data_path("pylhe-testlhef3.lhe")
events = pylhe.read_lhe_with_attributes(lhe_file)
print(f"Number of events: {pylhe.read_num_events(lhe_file)}")

# Get event 1
event = next(itertools.islice(events, 1, 2))

# A DOT language graph of the event can be inspected as follows
print(event.graph.source)

# The graph is nicely displayed as SVG in Jupyter notebooks
event

# To save a DOT graph render the graph to a supported image format
# (refer to the Graphviz documentation for more)
event.graph.render(filename="test", format="png", cleanup=True)
event.graph.render(filename="test", format="pdf", cleanup=True)

Writing

For a full example see write or filter. The values in the sketch below are intentionally left empty since they depend on the use-case. The data structure of pylhe is:

import pylhe

file=pylhe.LHEFile(
    init=pylhe.LHEInit(
        initInfo=pylhe.LHEInitInfo(
            beamA=,
            beamB=,
            energyA=,
            energyB=,
            PDFgroupA=,
            PDFgroupB=,
            PDFsetA=,
            PDFsetB=,
            weightinStrategy=,
            numProcesses=,
        ),
        procInfo=pylhe.LHEProcInfo(
            xSection=,
            error=,
            unitWeight=,
            procId=,
        ),
    ),
    events=[
        pylhe.LHEEvent(
            eventinfo=pylhe.LHEEventInfo(
                nparticles=,
                pid=,
                weight=,
                scale=,
                aqed=,
                aqcd=,
            ),
            particles=[
                pylhe.LHEParticle(
                    id=,
                    status=,
                    mother1=,
                    mother2=,
                    color1=,
                    color2=,
                    px=,
                    py=,
                    pz=,
                    e=,
                    m=,
                    lifetime=,
                    spin=,
                ),
                ...
            ],
            weights=None,
            attributes=None,
            optional=None,
        ),
        ...
    ]
)

# write to file, compressed if gz/gzip suffix
write_lhe_file(file.init, file.events, "myevents.lhe.gz", rwgt=True, weights=False)

Citation

The preferred BibTeX entry for citation of pylhe is

@software{pylhe,
  author = {Lukas Heinrich and Matthew Feickert and Eduardo Rodrigues and Alexander Puck Neuwirth},
  title = "{pylhe: v0.9.2}",
  version = {v0.9.2},
  doi = {10.5281/zenodo.1217031},
  url = {https://github.com/scikit-hep/pylhe},
}

Contributors

We hereby acknowledge the contributors that made this project possible (emoji key):

Matthew Feickert 🚧 🎨 💻 📖	Lukas 🚧 🎨 💻 📖	Eduardo Rodrigues 🚧 💻 📖	Johannes Schumann 💻	Henry Schreiner 💻	ariaradick 💻	Junghwan John Goh 💻
fuenfundachtzig 💻	Shantanu Gontia 💻	Tom Eichlersmith 💻	Alexander Puck Neuwirth 💻 📖 🚧	Iason Krommydas 💻 📖

This project follows the all-contributors specification.