.. _I3GenieReaderSegment:

I3GenieReaderSegment
====================

Reads GENIE Generator variables and then, if ``OutputSystWeights == True`` 
adds systematic weights specified in ``SystWghtFileNameList``.

This segment combines :ref:`I3GenieTracReader` (geometry resampling and GENIE event info conversion to ``.i3``) and :ref:`I3GenieSystWeightTracReader` (GENIE systematic weights conversion to ``.i3``) I3Modules.

.. caution::

    Requires both GST and GRooTracker root-files to read generator variables. 
    For systematic weights requires ReWeight output root-files.

Example usage 
^^^^^^^^^^^^^

For the full example see :file:`resources/scripts/step1_genie.py`

.. code-block:: python

  from icecube.icetray import I3Tray, I3Units
  from icecube import phys_services, genie_reader

  info = I3GenieInfo()		
  # fill input information in I3GenieInfo
  # ...

  tray = I3Tray()

  # Random number generator
  randomService = phys_services.I3SPRNGRandomService(
		                             seed = 1,
					     nstreams = 10,
					     streamnum = 1)

  tray.AddModule("I3InfiniteSource","streams",
		 Stream=icetray.I3Frame.DAQ)

  tray.AddSegment(genie_reader.I3GenieReaderSegment, 'genie_reader',
                  GenieFileGST = 'gntp.NuMu.A.1400002.gst.root',
                  GenieFileGRooTracker = 'gntp.NuMu.A.1400002.gtrac.root',
                  SystWghtFileNameList = ['systw.NuMu.A.1400002.MaCCRES.root', 'systw.NuMu.A.1400002.MaCCQE.root'],
                  GenieInfo = info,
                  RandomService=randomService,
                  IceDensity = 0.93*I3Units.g/I3Units.cm3,
                  GenVolCenter = I3Position(46.29,-34.88,-330.0),
                  OutputResultDict = True)
		  
Signature
^^^^^^^^^

.. autoclass:: icecube.genie_reader.I3GenieReaderSegment

Output objects
^^^^^^^^^^^^^^
I3GenieReaderSegment produces 5 types of output objects:

- ``I3GenieInfo`` in S-Frame
  (for the description see :ref:`I3GenieTracReader`)

- ``I3MCTree``, ``I3MCWeightDict`` and ``I3GenieResult`` in Q-Frame 
  (for the description see :ref:`I3GenieTracReader`)

- ``I3GenieSystWeightDict`` in Q-Frame if ``OutputSystWeights == True`` 
  and non-empty list of GENIE Reweight files is
  passes (for the description see :ref:`I3GenieSystWeightTracReader`)