groot/rjson: first import

[sbinet]

Fixes #991.

[sbinet]

^^ @mrceyhun

WDYT ?

(I have only implemented a (possibly narrow) subset of TH{1,2}x JSON marshaling)

// Copyright ©2023 The go-hep Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package rjson_test

import (
	"bytes"
	"encoding/json"
	"fmt"
	"log"

	"go-hep.org/x/hep/groot/rhist"
	"go-hep.org/x/hep/groot/rjson"
	"go-hep.org/x/hep/hbook"
)

func ExampleMarshal() {
	h := hbook.NewH1D(5, 0, 5)
	h.Fill(1, 1)
	h.Fill(-1, 1)
	h.Ann["name"] = "h1"
	h.Ann["title"] = "my title"

	raw, err := rjson.Marshal(rhist.NewH1FFrom(h))
	if err != nil {
		log.Fatalf("could not marshal to ROOT JSON: %+v", err)
	}

	buf := new(bytes.Buffer)
	err = json.Indent(buf, raw, "", "  ")
	if err != nil {
		log.Fatalf("could not indent JSON: %+v", err)
	}

	fmt.Printf("json: %s\n", buf.String())

	// Output:
	// json: {
	//   "_typename": "TH1F",
	//   "fUniqueID": 0,
	//   "fBits": 50331648,
	//   "fName": "h1",
	//   "fTitle": "my title",
	//   "fLineColor": 602,
	//   "fLineStyle": 1,
	//   "fLineWidth": 1,
	//   "fFillColor": 0,
	//   "fFillStyle": 1001,
	//   "fMarkerColor": 1,
	//   "fMarkerStyle": 1,
	//   "fMarkerSize": 1,
	//   "fNcells": 7,
	//   "fXaxis": {
	//     "_typename": "TAxis",
	//     "fUniqueID": 0,
	//     "fBits": 50331648,
	//     "fName": "xaxis",
	//     "fTitle": "",
	//     "fNdivisions": 510,
	//     "fAxisColor": 1,
	//     "fLabelColor": 1,
	//     "fLabelFont": 42,
	//     "fLabelOffset": 0.005,
	//     "fLabelSize": 0.035,
	//     "fTickLength": 0.03,
	//     "fTitleOffset": 1,
	//     "fTitleSize": 0.035,
	//     "fTitleColor": 1,
	//     "fTitleFont": 42,
	//     "fNbins": 5,
	//     "fXmin": 0,
	//     "fXmax": 5,
	//     "fXbins": [
	//       0,
	//       1,
	//       2,
	//       3,
	//       4,
	//       5
	//     ],
	//     "fFirst": 0,
	//     "fLast": 0,
	//     "fBits2": 0,
	//     "fTimeDisplay": false,
	//     "fTimeFormat": "",
	//     "fLabels": null,
	//     "fModLabs": null
	//   },
	//   "fYaxis": {
	//     "_typename": "TAxis",
	//     "fUniqueID": 0,
	//     "fBits": 50331648,
	//     "fName": "yaxis",
	//     "fTitle": "",
	//     "fNdivisions": 510,
	//     "fAxisColor": 1,
	//     "fLabelColor": 1,
	//     "fLabelFont": 42,
	//     "fLabelOffset": 0.005,
	//     "fLabelSize": 0.035,
	//     "fTickLength": 0.03,
	//     "fTitleOffset": 1,
	//     "fTitleSize": 0.035,
	//     "fTitleColor": 1,
	//     "fTitleFont": 42,
	//     "fNbins": 1,
	//     "fXmin": 0,
	//     "fXmax": 1,
	//     "fXbins": [],
	//     "fFirst": 0,
	//     "fLast": 0,
	//     "fBits2": 0,
	//     "fTimeDisplay": false,
	//     "fTimeFormat": "",
	//     "fLabels": null,
	//     "fModLabs": null
	//   },
	//   "fZaxis": {
	//     "_typename": "TAxis",
	//     "fUniqueID": 0,
	//     "fBits": 50331648,
	//     "fName": "zaxis",
	//     "fTitle": "",
	//     "fNdivisions": 510,
	//     "fAxisColor": 1,
	//     "fLabelColor": 1,
	//     "fLabelFont": 42,
	//     "fLabelOffset": 0.005,
	//     "fLabelSize": 0.035,
	//     "fTickLength": 0.03,
	//     "fTitleOffset": 1,
	//     "fTitleSize": 0.035,
	//     "fTitleColor": 1,
	//     "fTitleFont": 42,
	//     "fNbins": 1,
	//     "fXmin": 0,
	//     "fXmax": 1,
	//     "fXbins": [],
	//     "fFirst": 0,
	//     "fLast": 0,
	//     "fBits2": 0,
	//     "fTimeDisplay": false,
	//     "fTimeFormat": "",
	//     "fLabels": null,
	//     "fModLabs": null
	//   },
	//   "fBarOffset": 0,
	//   "fBarWidth": 1000,
	//   "fEntries": 2,
	//   "fTsumw": 2,
	//   "fTsumw2": 2,
	//   "fTsumwx": 0,
	//   "fTsumwx2": 2,
	//   "fMaximum": -1111,
	//   "fMinimum": -1111,
	//   "fNormFactor": 0,
	//   "fContour": [],
	//   "fSumw2": [
	//     1,
	//     0,
	//     1,
	//     0,
	//     0,
	//     0,
	//     0
	//   ],
	//   "fOption": "",
	//   "fFunctions": {
	//     "_typename": "TList",
	//     "name": "",
	//     "arr": [],
	//     "opt": []
	//   },
	//   "fBufferSize": 0,
	//   "fBuffer": [],
	//   "fBinStatErrOpt": 0,
	//   "fStatOverflows": 2,
	//   "fArray": [
	//     1,
	//     0,
	//     1,
	//     0,
	//     0,
	//     0,
	//     0
	//   ]
	// }
}

[sbinet]

^^ @mrceyhun ping ?

was this useful ?
(in the meantime, I've also added support for TGraph)

BTW, do you have a link to the repo that uses go-hep.org/x/hep/groot/... ?
(I'd like to add it to https://go-hep.org/users/#code)

[mrceyhun]

@sbinet sorry for the delay. I had to finish the project quickly and I could not have much time to use go-hep tools. I implemented required functionalities with PyROOT. May be I can replace PyROOT backend with go, so replace PyROOT with go-root. I'll give it try in my free time.

I don't know your future plan, most probably I'll need JSON representations of TH2F, TProfile and THStack too in my tests. Please note that no guarantee that this will go in production. That's why you can drop the request as you wish, no hard feeling :)