[DOC] Examples of the format

[mmikhasenko]

Please provide examples of the complete serialized files, building from a simple to more sophisticated case. It will improve adoption

You can have CI running and saving some root PDFs to examples that can be viewed

• Single standardized pdf, e.g. Gaussian
• Combination of several pdfs, e.g. product
• turning a function form "functions" into a pdf,
• "analyses"
• "likelihoods"

[mmikhasenko]

@cburgard @Cornelius-G it took me 40' to figure out how to produce the simplest HS3 file with root Consider including examples somewhere in this repository or elsewhere. I believe, It will speed up the adoption

Leaving notes for anyone trying to look at hs3

1. go to lxplus, set up the env to the latest root, open root

   ssh lxplus.cern.ch
   source /cvmfs/sft.cern.ch/lcg/views/dev3/latest/x86_64-el9-gcc13-opt/setup.sh 
   root -l

2. Create and write a gaussian PDF

   
   // create a 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) ;

// put it to a workspace RooWorkspace w("ws"); w.import(gauss);

// export with RooJSONFactoryWSTool tool = RooJSONFactoryWSTool(w); auto tool = RooJSONFactoryWSTool(w); tool.exportJSON("test.json")

3. Check the result,
```json
{
  "distributions": [
    {
      "mean": "mean",
      "name": "gauss",
      "sigma": "sigma",
      "type": "gaussian_dist",
      "x": "x"
    }
  ],
  "domains": [
    {
      "axes": [
        { "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"
    }
  ],
  "metadata": {
    "hs3_version": "0.2",
    "packages": [{ "name": "ROOT", "version": "6.33.01" }]
  },
  "parameter_points": [
    {
      "name": "default_values",
      "parameters": [
        { "name": "x", "value": 0.0 },
        { "name": "mean", "value": 1.0 },
        { "name": "sigma", "value": 1.0 }
      ]
    }
  ]
}

4. Useful links:
   • RooJSONFactoryWSTool
   • RooWorkspace.importpage 15 of intro slides

[mmikhasenko]

Related to #4

[cburgard]

Hi Misha! Sorry for the inconvenience, and you are absolutely right, we should put an example like this in the top-level of our repo! I'll copy & paste your instructions to a README in the next days (you can do it yourself also if you want to take credit, which you are welcome to do) and merge it to master!