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Functor Collections

Abstract

  • Learn what functor collections are and how to implement them.

We saw in the last section how we can add many different functors to our tuple. This can create very large DaVinci scripts and it can sometimes be easy to forget a functor you actually meant to include! This functionality is great as it means we can specify exactly what values we want calculated, saving resources, but sometimes you want to apply a predefined collection of these. We will mention a few and what they include and then provide an example where these are being used!

Candidate level Functor Collections

We will start off with the simplest functor collection called FC.Kinematics, this will add:

F.MASS
F.P
F.PT
F.PX
F.PY
F.PZ
F.ENERGY

This is easily included as in the snippet below:

all_vars += FC.Kinematics()

This will apply all 7 functors to all the variables, if you only want to apply certain collections to the tracks or the composites then this can simply be done as so:

track_variables += FC.Kinematics()
composite_variables += FC.Kinematics()

There are a large variety of other functor collections that can be found in the docs here. I will discuss some other common ones that may be of interest.

For PID variables you can add:

track_variables += FC.ParticleID()

This will include

F.PARTICLE_ID
F.PROBNN_D
F.PROBNN_E
F.PROBNN_GHOST
F.PROBNN_K
F.PROBNN_MU
F.PROBNN_P
F.PROBNN_PI

and by passing FC.ParticleID(extra_info = True) this will also supply the standard PID variables.

Two more functor collections I will highlight here are ParticlePVInfo and FC.ChargedCaloInfo, with the former giving information on OWNPVX, OWNPVY, OWNPVZ and OWNPV_NDOF. Whilst the latter gives information based on the ECAL and HCAL quantities.

Event level Functor Collections

All of these functor collections so far are candidate level variables, they act per reconstructed candidate. However we are also interested in event level information. These can be easily integrated into our funtuple algorithm as so:

funtuple = Funtuple(
    name=line,
    tuple_name="DecayTree",
    fields=fields,
    variables=variables,
    inputs=data,
    event_variables=evt_variables,  # This additional event variables argument
)
Where you can just add a new functor collection called evt_variables and add event level quantities to it. Some examples of these are:

AllPrimaryVertexInfo
RecSummary
LHCInfo
EventInfo

Each collection can be looked up in the docs here. Each of these can be added like so:

evt_variables = FC.LHCInfo(),
evt_variables += FC.EventInfo(),