Simulation

Processor that stores the simulation an IceCube file was generated with, and extracts the per-event quantities needed to weight it, using simweights.

It emits the inputs to a weight calculation rather than a weight. Baking a number in during processing would fix the mixture at processing time. Instead this processor stores the per-event generation quantities as columns and the shard’s generation info under attrs.LOCAL.simulation:

simulation:
  sim_code: 173502938116405
  type: corsika
  column: sim_code
  nfiles: 14
  corsika_info: ...

A shard is a collected block of input files. nfiles counts every one of them, including files without events. On load, the surface of each set is built by simweights over the shards actually read, as nfiles summed over them. No shard depends on another, so any can be dropped without reprocessing the rest. A shard without the attribute is inferred to be real data and thus has no weights.

The generation info is stored like so:

• corsika_info: the I3CorsikaInfo S-frames of every file of the shard. Every CORSIKA file is required to carry them, including files without events. A file without them raises.

• weight_dict: one I3MCWeightDict row per neutrino type.

The sim code, carried in the generation column named by column, routes each event to the correct weighter on load. It can be discovered automatically from the generation info or specified manually:

• CORSIKA: one code for all files.

• NuGen: a hash of the generation info shared by every type a file threw, and of the neutrino flavor. A shard is assumed to contain only one flavor and a shard holding several is refused unless sim_code is configured manually.

Configuration

Selected as name: i3-simulation.

Option	Description	Type	Default
type	Simulation type: nugen, corsika.	str	required
ids	ID columns keying the output frame, read from the event table.	str | int | list	the event ids
to	Working frame the extracted columns are written to.	str	generation
sim_code	Code used to route events to the correct weighter on load. Discovered from the generation info if not given.	int	discovered
weight_dict	Key of the NuGen weight dict.	str	I3MCWeightDict
corsika_info	Key of the CORSIKA S-frames.	str	I3CorsikaInfo
primary	Key of the CORSIKA primaries.	str	PolyplopiaPrimary

- name: i3-simulation
  kwargs:
    type: corsika

The processor reads from the extracted frames directly, so it does not need an active frame.

Note

The columns this processor writes are joined onto the output on the id columns. An event holding features but no row in the event table joins to null.