Format crosscheck, downstream pipeline

[mmikhasenko]

A lot of time will pass before we start seeing ROOT capability to read the files with amplitude model.
However, some cross-check of the format can done at earlier stages.

This issue gives example on how to write HS3 json from root.

[mmikhasenko]

Extended example of root json

ROOT script

#include "RooRealVar.h"
#include "RooGaussian.h"
#include "RooExponential.h"
#include "RooBreitWigner.h"
#include "RooWorkspace.h"
#include "RooFitHS3/RooJSONFactoryWSTool.h"

int export_pdf()
{
    RooRealVar x("x", "x", -10, 10);
    RooRealVar mean("mean", "mean of gaussian", 1, -10, 10);
    RooRealVar sigma("sigma", "width of gaussian", 1, 0.1, 10);
    RooGaussian gauss("gauss", "gaussian PDF", x, mean, sigma);
    // w.factory(“Gaussian::f(x[-10,10],mean[5],sigma[3])”)

    RooRealVar alpha("alpha", "slope or exp", 1, 0.1, 10);
    RooExponential exp("exp", "exponential PDF", x, alpha);

    RooRealVar gamma("gamma", "width of bw", 1, 0.1, 10);
    RooBreitWigner bw("bw", "non-rel bw", x, mean, gamma);

    RooWorkspace w("ws");
    w.import(gauss);
    w.import(exp);
    w.import(bw);

    RooJSONFactoryWSTool tool(w);
    tool.exportJSON("standard_pdf.json");
    return 0;
}

JSON output

{
  "distributions": [
    { "name": "bw" },
    {
      "c": "alpha_exponential_inverted",
      "name": "exp",
      "type": "exponential_dist",
      "x": "x"
    },
    {
      "mean": "mean",
      "name": "gauss",
      "sigma": "sigma",
      "type": "gaussian_dist",
      "x": "x"
    }
  ],
  "domains": [
    {
      "axes": [
        { "max": 10.0, "min": 0.1, "name": "alpha" },
        { "max": 10.0, "min": -10.0, "name": "mean" },
        { "max": 10.0, "min": 0.1, "name": "sigma" },
        { "max": 10.0, "min": -10.0, "name": "x" }
      ],
      "name": "default_domain",
      "type": "product_domain"
    }
  ],
  "functions": [
    {
      "expression": "-alpha",
      "name": "alpha_exponential_inverted",
      "type": "generic_function"
    }
  ],
  "metadata": {
    "hs3_version": "0.2",
    "packages": [{ "name": "ROOT", "version": "6.33.01" }]
  },
  "misc": {
    "ROOT_internal": {
      "attributes": {
        "alpha_exponential_inverted": {
          "dict": { "autogen_transform_exponential_original": "alpha" },
          "tags": ["autogen_transform_exponential"]
        }
      }
    }
  },
  "parameter_points": [
    {
      "name": "default_values",
      "parameters": [
        { "name": "x", "value": 0.0 },
        { "name": "alpha", "value": 1.0 },
        { "name": "mean", "value": 1.0 },
        { "name": "sigma", "value": 1.0 }
      ]
    }
  ]
}

Warning about BreitWigner

Processing export_pdf.cxx++...
Info in <TUnixSystem::ACLiC>: creating shared library /afs/cern.ch/user/m/mimikhas/Documents/HS3/./export_pdf_cxx.so
[#1] INFO:ObjectHandling -- RooWorkspace::import(ws) importing RooGaussian::gauss
[#1] INFO:ObjectHandling -- RooWorkspace::import(ws) importing RooRealVar::x
[#1] INFO:ObjectHandling -- RooWorkspace::import(ws) importing RooRealVar::mean
[#1] INFO:ObjectHandling -- RooWorkspace::import(ws) importing RooRealVar::sigma
[#1] INFO:ObjectHandling -- RooWorkspace::import(ws) importing RooExponential::exp
[#1] INFO:ObjectHandling -- RooWorkspace::import(ws) importing RooRealVar::alpha
[#1] INFO:ObjectHandling -- RooWorkspace::import(ws) importing RooBreitWigner::bw
[#1] INFO:ObjectHandling -- RooWorkspace::import(ws) importing RooRealVar::gamma
unable to export class 'RooBreitWigner' - no export keys available!
there are several possible reasons for this:
 1. RooBreitWigner is a custom class that you or some package you are using added.
 2. RooBreitWigner is a ROOT class that nobody ever bothered to write a serialization definition for.
 3. something is wrong with your setup, e.g. you might have called RooFit::JSONIO::clearExportKeys() and/or never successfully read a file defining these keys with RooFit::JSONIO::loadExportKeys(filename)
either way, please make sure that:
 3: you are reading a file with export keys - call RooFit::JSONIO::printExportKeys() to see what is available
 2 & 1: you might need to write a serialization definition yourself. check https://github.com/root-project/root/blob/master/roofit/hs3/README.md to see how to do this!

[mmikhasenko]

Superseded by #58