Plotting multiple histograms in same canvas

Newbie
1

I have two root files and want to plot the histograms from each one together in the same canvas;
I used this code, but what I get is only the last plot and it is ignore the first plot completely, it didn’t give me any error messages.

TFile *f1 = TFile::Open("160primary.root");
TH1D *h1= (TH1D*)f1->Get("Position_X__cm_");
h1->Draw("hist l");
h1->SetLineWidth(3);
h1->SetLineColor(2);

TFile *f2 = TFile::Open("130primary.root");
TH1D *h2 = (TH1D*)f2->Get("Position_X__cm_");
h2->SetLineWidth(2);
h2->SetLineColor(4);
h2->Draw("hist l same");

any help will be deeply appreciated.

2

Welcome to the ROOT forum

Weird, that code should produce the two plots on the same canvas as you plot the 2nd one with the option “same”. The range along X and Y axis is defined by the first plot. Can you provide a code we can run ?

3

thanks for your help
I am trying to upload the file but it refused.

4

I got a message saying new users can not send links can you advise me how to upload it ?

5

An other way is to use THStack.

TFile *f1 = TFile::Open("160primary.root");
TH1D *h1= (TH1D*)f1->Get("Position_X__cm_");
h1->SetLineWidth(3);
h1->SetLineColor(2);

TFile *f2 = TFile::Open("130primary.root");
TH1D *h2 = (TH1D*)f2->Get("Position_X__cm_");
h2->SetLineWidth(2);
h2->SetLineColor(4);

auto hs = new THStack();
hs->Add(h1,"HIST L");
hs->Add(h2,"HIST L");
hs->Draw("NOSTACK");
6

thanks a lot
but it give me this message
*** Break *** segmentation violation

[/usr/lib/system/libsystem_platform.dylib] _sigtramp (no debug info)

[] (no debug info)

[] (no debug info)

[/opt/local/libexec/root6/lib/root/libCling.6.24.06.so] cling::IncrementalExecutor::executeWrapper(llvm::StringRef, cling::Value*) const (no debug info)

[/opt/local/libexec/root6/lib/root/libCling.6.24.06.so] cling::Interpreter::RunFunction(clang::FunctionDecl const*, cling::Value*) (no debug info)

[/opt/l…

7

Which line gives this error ?

9

That’s totally un-clear… “TCanvas instead of TH1D” ?
have a look at the documentation…

10

thanks a lot for your help
I managed to solve the problem