Kfactors
=========

Another useful tool that `pineko` includes is ``pineko kfactor`` which allows the embedding of a kfactor
as a proper order in a grid. The usage is the following::

  pineko kfactor THEORY_ID DATASET KFACTOR_FOLDER TARGET_FOLDER PTO_TO_UPDATE [--order_exists]

where:

- ``THEORY_ID``  is the theory ID of the source grid,
- ``DATASET`` is the dataset name,
- ``KFACTOR_FOLDER`` is the folder containing the kfactor files,
- ``TARGET_FOLDER`` is the folder where the new updated grids is going to be saved,
- ``PTO_TO_UPDATE`` is the :math:`\alpha_s` perturbative order to update or create,
  with the convention that ``LO=1``, ``NLO=2`` and so on, irrespectively to the powers of :math:`\alpha_s`.
  Note also that this differs from the conventions by the NNPDF collaboration,
  but it is consistent with the pineappl convention.
- ``--order_exists`` is a flag used to apply the kfactor to the specified perturbative order, insead of the next.

Note that only pure QCD kfactors are taken into account.
For example to add the NNLO in a grid containing at most NLO one has to select ``PTO_TO_UPDATE=2``;
nn the other hand to reweight the NNLO present in a grid with a kfactor,
one should do ``PTO_TO_UPDATE=2 --order_exists``.