Problem with coffea and fastJet

[Mmiglio]

Hi all,
I'm trying to read a custom root tree with NanoEvents (BaseSchema), build a cluster sequence with Fastjet and fill some histograms.
Basically, it boils down to the following pieces of code:
Read the events with

events = NanoEventsFactory.from_root(...).events()

create a vector of particles with vector

vector.register_awkward()

pVec = ak.zip(
    {
        "pt": events['p_pt'],
        "eta": events['p_eta'],
        "phi": events['p_phi'],
        "energy": events['p_e']
    },
    with_name="Momentum4D",
    )

and running the clustering sequence

jetDef = fastjet.JetDefinition(fastjet.antikt_algorithm, 0.8)
clusters = fastjet.ClusterSequence(pVec, jetDef)

wideJets = clusters.inclusive_jets()
wideJets.compute()

However, in this last step I get the error

2024-05-29 22:54:59,642 - distributed.worker - WARNING - Compute Failed
Key:       ('inclusive-jets-ce369f847f3668e7ee635bd961e39de2', 0)
Function:  subgraph_callable-e581127c15a3754284aa7f4bf45b8373
args:      ('p_pt', 'p_phi', 'p_eta', 'p_e', ('./QCD_30to50/output_1.root', 'Events', 0, 1, False))
kwargs:    {}
Exception: 'AttributeError("no field named \'px\'")'

I've tried to change the definition of pVec, by using

p = ak.zip(
    {
        "pt": events['p_pt'],
        "eta": events['p_eta'],
        "phi": events['p_phi'],
        "energy": events['p_e']
    },
    with_name="PtEtaPhiECandidate",
    behavior=candidate.behavior,
    )

and , running wideJets.compute() returns the expected result!

However, trying to do something like wideJets.pt.compute(), or simply using wideJets.pt to fill a hist will cause an error similar to the previous one, saying

Exception: 'AttributeError("no field named \'pt\'")'

Am I doing something wrong? I could come up with some workarounds, but my final goal would be to integrate this into a Processor and apply it to a file set. I don't think calling `wideJets.compute()' is the right way, but I might be wrong.

I'm using

coffea 2024.3.0
awkward 2.6.2
dask_awkward 2024.3.0
fastjet 3.4.1.3

Thanks for your help!

[ikrommyd]

Everything works for me. I'm on slightly newer versions though.

coffea 2024.5.0
awkward 2.6.5
dask_awkward 2024.3.0
fastjet 3.4.1.3

In [15]: from coffea.nanoevents import NanoEventsFactory

In [16]: events = NanoEventsFactory.from_root({"https://github.com/CoffeaTeam/coffea/raw/master/tests/samples/nano_dy.root": "Events"}).events()
/usr/local/lib/python3.10/site-packages/coffea/nanoevents/methods/candidate.py:11: FutureWarning: In version 2024.7.0 (target date: 2024-06-30 11:59:59-05:00), this will be an error.
To raise these warnings as errors (and get stack traces to find out where they're called), run
    import warnings
    warnings.filterwarnings("error", module="coffea.*")
after the first `import coffea` or use `@pytest.mark.filterwarnings("error:::coffea.*")` in pytest.
Issue: coffea.nanoevents.methods.vector will be removed and replaced with scikit-hep vector. Nanoevents schemas internal to coffea will be migrated. Otherwise please consider using that package!.
  from coffea.nanoevents.methods import vector
/usr/local/lib/python3.10/site-packages/coffea/nanoevents/schemas/nanoaod.py:243: RuntimeWarning: Missing cross-reference index for FatJet_genJetAK8Idx => GenJetAK8
  warnings.warn(

In [17]: vector.register_awkward()
    ...:
    ...: pVec = ak.zip(
    ...:     {
    ...:         "pt": events.Jet.pt,
    ...:         "eta": events.Jet.eta,
    ...:         "phi": events.Jet.phi,
    ...:         "energy": events.Jet.E
    ...:     },
    ...:     with_name="Momentum4D",
    ...:     )

In [18]: jetDef = fastjet.JetDefinition(fastjet.antikt_algorithm, 0.8)
    ...: clusters = fastjet.ClusterSequence(pVec, jetDef)
    ...:
    ...: wideJets = clusters.inclusive_jets()
    ...: wideJets.compute()
Out[18]: <MomentumArray4D [[{px: -40.3, py: ..., ...}, ...], ...] type='40 * var * M...'>

In [19]: from coffea.nanoevents.methods import candidate

In [20]: vector.register_awkward()
    ...:
    ...: pVec = ak.zip(
    ...:     {
    ...:         "pt": events.Jet.pt,
    ...:         "eta": events.Jet.eta,
    ...:         "phi": events.Jet.phi,
    ...:         "energy": events.Jet.E
    ...:     },
    ...:     with_name="PtEtaPhiECandidate",
    ...:     behavior=candidate.behavior,
    ...:     )

In [21]: jetDef = fastjet.JetDefinition(fastjet.antikt_algorithm, 0.8)
    ...: clusters = fastjet.ClusterSequence(pVec, jetDef)
    ...:
    ...: wideJets = clusters.inclusive_jets()
    ...: wideJets.compute()
Out[21]: <MomentumArray4D [[{px: -40.3, py: ..., ...}, ...], ...] type='40 * var * M...'>

In [22]: wideJets.pt
Out[22]: dask.awkward<pt, npartitions=1>

In [23]: wideJets.pt.compute()
Out[23]: <Array [[45.6, 59.4, 80.8], [...], ..., [18.3, 18.8]] type='40 * var * float64'>

[lgray]

Does this problem persist with the most recent version of fastjet? (3.4.2.0)

[Mmiglio]

I will try! out of curiosity, why isn't version 3.4.2.0 the latest version on pypi as well?

[lgray]

Oh there may have been some problem in publishing the release. Right. Try compiling from source.

[Mmiglio]

Still failing, event with fastjet 3.4.2.0 :(
I found this issue scikit-hep/fastjet#238. Seems like this has been a long standing problem.

[lgray]

I'll see if I can find someone with the free time to fix it. If you have interest to do so, please let me know!