Plot variable vs event number from tree

ROOT
1

Simple question:

I’d like to plot a variable from a tree vs it’s event number. e.g. if I had a variable “energy” stored in a tree “tree” I’d write something like:

tree->Draw(“energy:eventNumber”)

The question is what should “eventNumber” be? I’m sure there’s some sort of internal variable in the tree but can’t remember the name.

Many thanks
Jamie

2

See “Special functions and variables” (or search for “$”) in the TTree::Draw method description.