JSRoot - set axis range

[meleneemil]

Dear root-ers,

I’d like to create a TRatioPlot with JSRoot. The class doesn’t seem available.
As a workaround, I thought to make a second histo below the original, and with a setInterval call, to update the xAxis range of the one wrt the other.

However, I don’t find yet how to (programmatically in JS) set the range of the axis/histo.

Thanks for any tip
Emil

[linev]

Hi Emil,

TRatioPlot is complicated class with several cross-references.
Therefore JSROOT does not provide method to create it.

I recommend to create it in the ROOT, store as JSON and then embed such JSON into JavaScript.
In such case you will be able to modify it to your need - including replacing of the content or changing axis labels.

Display of TRatioPlot should work. See several examples here:

JSROOT examples

Regards,
Sergey

[meleneemil]

Thanks Sergey,

for my current application, I handle objects directly online (online monitoring of histograms published in the experiment website), so I don’t really have an option for making ROOT files as it is; I could change the approach completely if all else fails.

Is there no way to handle the histo/canvas axis zoom from the xml object?

thanks again
Emil

[linev]

You can create dummy TRatioPlot object with some default histograms once and reuse it every time you need to put some new data in.

[meleneemil]

I guess you mean to make the dummy TRatioPlot in a root file that I can access, and then, within the xml object, I can access the internal histos that are plotted, and set them to what I make in the js code?

If yes, I think it makes sense, will try in a bit.
If not, then, please explain a bit more; I haven’t (js)root-ed in a long while and am rusty

Also, could you please point to where one can download the example root files that are linked under

JSROOT examples

I can’t find them yet
EDIT: found fiddling with the URL
https://root.cern/js/files/ratioplot.root

thanks again
Emil

[linev]

I recommend to generate JSON.

Just take any example like tutorials/hist/ratiplot5.C

Add as the last line: rp1->SaveAs("rp5.json");

Produced json insert into your code. Do not forget parse it:

import { parse } from 'https://root.cern/js/latest/modules/core.mjs';

let code =  
   // here should be content of rp5.json file
;

let obj = parse(code);

[meleneemil]

Hi Sergey

1. maybe I miss something obvious, but I cannot find the tutorials folder. Would be nice to have a link in the main jsRoot pages

2. Until I find the json one, I load the TCanvas of a TRatioPlot from the ratioplot.root file, and I see the xml, but I don’t see yet what needs to be set to use my own histograms in place of the ones in canvas
   I tried to set fH1 and fH2 under obj.fPrimitives.arr[3] (TRatioPlot), but it doesn’t change yet…)

thanks again
Emil

[linev]

@meleneemil

maybe I miss something obvious, but I cannot find the tutorials folder. Would be nice to have a link in the main jsRoot pages

It is in $ROOTSYS/tutorials directory. You also can find them in the repository

@meleneemil

Until I find the json one, I load the TCanvas of a TRatioPlot from the ratioplot.root file, and I see the xml, but I don’t see yet what needs to be set to use my own histograms in place of the ones in canvas

That’s why I recommend to use JSON - there it is relatively clear how to access necessary objects and modify them.