X axis max/min Tgraph

Newbie
1

Hi, is there a way to take the max and the min X value from a Tgraph?
I’ve a TTree and i need the range xmax-xmin of the graph i have from the ttree.

2

For a tree:
TTree::GetMinimum
TTree::GetMaximum

For a “graph”:
TMath::MinElement(graph->GetN(), graph->GetX())
TMath::MaxElement(graph->GetN(), graph->GetX())

3

It might be overall fewer lines with RDataFrame. To just get the min/max of a column, maybe conditional to a cut, these are all the lines you need:

auto selected_df = ROOT::RDataFrame("treename", "filename.root").Filter("x > 0");
auto min = df.Min("x");
auto max = df.Max("y");

To create a TGraph from an RDataFrame:

ROOT::RDataFrame df("treename", "files/*.root");
graph = df.Graph("x", "y");

Cheers,
Enrico

4

it says error: no member named ‘MaxElement’ in ‘TGraph’

6

i don’t understand the value i have in output on the terminal.

8

oh sorry, all is correct! i was wrong with copy/paste…