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Changes between Version 68 and Version 69 of HowToAddSample


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Timestamp:
Jan 6, 2017, 11:16:07 PM (7 years ago)
Author:
Clarence Wret
Comment:

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  • HowToAddSample

    v68 v69  
    33This is an informal step-by-step guide on how to add samples into the NUISANCE framework. Most of this can be derived by looking at the recently [https://nuisance.hepforge.org/trac/browser/src?order=date&desc=1 implemented measurements] for up-to-date references.
    44
    5 For this tutorial I'll be adding the '''T2K CC1π^+^ H,,2,,O data'''. The data comes from the [http://t2k-experiment.org/results/nd280data-numu-cc1pi-xs-on-h2o-2015/ T2K site] and [https://arxiv.org/abs/1605.07964 arxiv]. The data is supplied [http://t2k-experiment.org/wp-content/uploads/nd280data-numu-cc1pi-xs-on-h2o-2015.tar both in a ROOT file and a number of .csv files]: I'll be using the ROOT file here but very similar steps apply when using .csv or .txt. files.
     5For this tutorial I'll be adding the '''T2K CC1π^+^ H,,2,,O data'''. The data comes from the [http://t2k-experiment.org/results/nd280data-numu-cc1pi-xs-on-h2o-2015/ T2K site] and [https://arxiv.org/abs/1605.07964 arxiv]. The data is supplied [http://t2k-experiment.org/wp-content/uploads/nd280data-numu-cc1pi-xs-on-h2o-2015.tar both in a ROOT file and a number of .csv files]: I'll be using the ROOT file here but very similar steps apply when using .csv or .txt files.
    66
    77After implementing we'll be able to make data/MC comparisons to the T2K CC1π^+^ H,,2,,O data for NEUT, GENIE, GiBUU and !NuWro, all in the same framework. We'll get MC predictions, χ^2^ values, interaction mode contributions, and more using a consistent signal definition, guaranteed the same across the generators.
     
    7878'''What to do:'''
    7979
    80 Following the above convention, we end up with '''`T2K_CC1pip_H2O_XSec_1Dpmu_nu`'''.
     80Following the above convention, we end up with '''`T2K_CC1pip_H2O_XSec_1Dpmu_nu`''' and '''`T2K_CC1pip_H2O_XSec_1DEnuMB_nu`'''.
    8181
    8282This is a sufficient name: there is no ambiguity what the class describes and there is no way of confusing it with other classes in NUISANCE.
     
    9494'''What to do:'''
    9595
    96 Make the new files '''`src/T2K/T2K_CC1pip_H2O_XSec_1Dpmu_nu.cxx`''' and '''`src/T2K/T2K_CC1pip_H2O_1Dpmu_nu.h`'''. These are the implementation and header files for the new measurement.
     96Make the new files '''`src/T2K/T2K_CC1pip_H2O_XSec_1Dpmu_nu.cxx`''' and '''`src/T2K/T2K_CC1pip_H2O_1Dpmu_nu.h`'''. These are the implementation and header files for the new measurement and similar goes for the `1DEnuMB` implementation.
    9797
    9898
     
    124124== Writing the header ==
    125125
    126 The T2K CC1π^+^ H,,2,,O data is all 1D distributions. The new classes should therefore inherit from the `Measurement1D` base class, as mentioned [#point_base earlier]. The `Measurement1D` class is implemented in `src/FitBase/Measurement1D.cxx`.
     126The T2K CC1π^+^ H,,2,,O data are all 1D distributions. The new classes should therefore inherit from the `Measurement1D` base class, as mentioned [#point_base earlier]. The `Measurement1D` class is implemented in `src/FitBase/Measurement1D.cxx`.
    127127
    128128NUISANCE requires a `constructor` and `destructor` for the class, and we'll need to overload `MeasurementBase` methods which define the dependent variable(s) (p,,µ,, and E^rec^,,ν,, in our case) and what our signal is (CC interaction with one muon and one positive pion with no other pions or mesons and any number of nucleons in our case). The `MeasurementBase` functions which we need to overload are `MeasurementBase::isSignal(FitEvent *event)` and `MeasurementBase::FillEventVariables(FitEvent *event)`.
     
    131131
    132132[=#point_signal]
    133 We see that the `src/T2K` directory contains `T2K_SignalDef.cxx`. This extends the `SignalDef` namespace which holds many of the signal definitions for the classes. If you're implementing multiple distributions for the same measurement (e.g. dSig/dp,,µ,, and dSig/dcosθ,,µ,,) we recommend adding the signal definition to the namespace rather than directly in the `isSignal(FitEvent *event)` function in the class implementation. We'll talk about implementing a signal definition [#point_signaldef later].
     133We also note that the `src/T2K` directory contains `T2K_SignalDef.cxx`. This extends the `SignalDef` namespace which holds many of the signal definitions for the classes. `SignalDef` itself lives in `src/Utils/SignalDef.cxx`, but may see additions from experiment folders such as `src/T2K/T2K_SignalDef.cxx`.
     134
     135If you're implementing multiple distributions for the same measurement (e.g. dσ/dp,,µ,, and dσ/dcosθ,,µ,,) we recommend adding the signal definition to the namespace rather than directly in the `isSignal(FitEvent *event)` function in the class implementation. We'll talk about implementing a signal definition [#point_signaldef later].
    134136
    135137
     
    160162where we've copied the constructor arguments from some other class we're using as a template. I'll elaborate more on this [#point_const below].
    161163
     164Note the simple structure for the sample: we really only need to set up three functions. The inheritance from `Measurement1D` and helper function within it does most of the heavy lifting.
     165
    162166
    163167[=#point_const]
    164168== Writing the constructor ==
    165169
    166 NUISANCE loads samples through `FCN/SampleList.cxx` in the function `SampleUtils::LoadSample`, which makes a `std::list` of `MeasurementBase` pointers which it later loops over from the executables.
     170NUISANCE loads samples through `FCN/SampleList.cxx` in the function `SampleUtils::LoadSample`. This function makes a `std::list` of `MeasurementBase` pointers which it later loops over in calls from the executables.
    167171
    168172Most of the automated setting up of histograms, titles, and so on is done in `Measurement1D::SetupMeasurement(std::string inputfile, std::string type, FitWeight *rw, std::string fakeDataFile)`. It hence makes sense to have a class constructor which passes all of these on to `SetupMeasurement`.
     
    225229The data and covariance matrix are available in a ROOT file for the sample, so I used `Measurement1D::SetDataFromFile` to set up the data and `Measurement1D::SetCovarFromDataFile` to set up the covariances.
    226230
    227 `fName` and the other `std::string`s were set to reasonable names and `fScaleFactor` was
     231`fName` and the other `std::string`s were set to reasonable names and `fScaleFactor` was set to the default mentioned above.
    228232
    229233The `constructor` for the class now looks like:
     
    263267We are now at the point where we can write the `FillEventVariables(FitEvent *event)` implementation mentioned [=#point_header above]. This function defines the dependent variable(s) and how to get them from each `FitEvent` object that gets passed.
    264268
    265 This is where the p,,μ,, and E^rec^,,ν,, implementations differ.
    266 
    267 The `FitEvent` class provides numerous getter functions to make `FillEventVariables` as simple as possible.
     269The `FitEvent` class provides numerous getter functions to make `FillEventVariables` implementation as simple as possible.
     270
     271This is the only major point where the p,,μ,, and E^rec^,,ν,, implementations differ.
    268272
    269273[=#point_muon_dist]
     
    337341}}}
    338342
    339 We should now write a helper function in the `FitUtils` namespace to get `E^rec^,,ν,,` from the muon, pion and neutrino `TLorentzVector`s. [https://arxiv.org/pdf/1605.07964v2.pdf The paper] specifies the exact form in equation 1. The `FitUtils` implementation lives in `src/Utils/FitUtils.cxx`.
     343We should now write a helper function in the `FitUtils` namespace to get E^rec^,,ν,, from the muon, pion and neutrino `TLorentzVector`s. [https://arxiv.org/pdf/1605.07964v2.pdf The paper] specifies the exact form in equation 1. The `FitUtils` implementation lives in `src/Utils/FitUtils.cxx`.
    340344
    341345{{{