How to draw a TH1 from a TTree branch with a selection in JSROOT?

ROOT
1

Dear experts,

I’m new to using JSROOT. I was wondering if there is a way to draw a TH1, from a TBranch of a TTree, by applying a selection directly from the web interface, without modifying the JavaScript code.

For instance, by opening this sample file:

https://root.cern.ch/js/latest/api.htm#url_syntax_open_file

I would like to display the following histogram:

ntuple->Draw(“px”, “py>0”)

Thank you in advance for your assistance.

Best regards,

Marco

2

Hi Marco,

There is section “TTree draw” in JSROOT documentation.

It also explains how to use cut expression. In your case draw option for the tree should be “px::py>0”. Full link is:

https://root.cern/js/latest/?file=../files/hsimple.root&item=ntuple&opt=px::py>0

Regards,
Sergey

3

Hi Sergey,

It worked. Thank you very much for your prompt response.

Best regards,
Marco