Superimpose 6 existing histograms

radgs · May 16, 2015, 3:02pm

Hi!

I have already made six histograms and they are stored in six different .root files, located not in root directory. I wanted to know how can I superimpose all of them and add a legend to each of them (by writing a macro.C file or just using root terminal).

Can anyone help?

jfcaron · May 17, 2015, 4:00am

Load each of them into memory (by opening the different TFiles and Get each one). Create a THStack to put them in, then draw the THStack with the “nostack” option. The gPad should have a useful BuildLegend method, or make a TLegend object and add each of the histograms to it manually. Then draw the TLegend.

Jean-François

radgs · May 20, 2015, 9:14pm

How do you get each one?

I write the following:

[code]- TFile f(“dir_of_the_root_file_”);

TH1F h1 = (TH1F)f.Get(“p1”);[/code]

But this last step gives the following error:

Error: Symbol f is not defined in current scope (tmpfile):1:

Can anyone help?

Also, I am using this THStack (within canvas) code:

[code]TCanvas *hstack() {

THStack *hs = new THStack(“hs”,“Stacked 1D histograms”);
h1>SetFillColor(kRed);
h1->SetMarkerColor(kRed);
hs->Add(h1st);

TCanvas *cst = new TCanvas(“cst”,“stacked hists”,0, 0, 1000, 1000);

//the parameters below are optional and I will edit them when I can run the THStack this code.
cst->SetFillColor(41);
cst->Divide(2,2);
cst->cd(1);
hs->Draw();
cst->cd(2);
gPad->SetGrid();
hs->Draw(“nostack,e1p”);
cst->cd(3);
gPad->SetFrameFillColor(17);
gPad->SetTheta(3.77);
gPad->SetPhi(2.9);
hs->Draw(“lego1”);
{[/code]

If anything seems suspicious on the code I wrote let me know.
Thank you.

couet · May 21, 2015, 6:22am

It is hard to tell what goes wrong in your TFile command as you do not show the real command you performed. You should do something like:

TFile f("file1.root");
TH1F *h1 = (TH1F*)f.Get("h1");

TFile f("file2.root");
TH1F *h2 = (TH1F*)f.Get("h2");

TFile f("file3.root");
TH1F *h3 = (TH1F*)f.Get("h3");

THStack *hs = new THStack("hs","Stacked 1D histograms");
hs->Add(h1);
hs->Add(h2);
hs->Add(h3);

hs->Draw();

radgs · May 21, 2015, 9:00am

When I do

root [0] TFile f("file.root"); root [1] TH1F *h1 = (TH1F*)f.Get("h1");
It is all fine.

But after doing that, when I do the following:

root [2] TFile f("file2.root"); root [3] TH1F *h2 = (TH1F*)f.Get("h2");

Appears the following error:

Error: Symbol f is not defined in current scope (tmpfile):1: Error: Failed to evaluate f.Get("h2") *** Interpreter error recovered ***

The strange thing is that if I do the same command again (for file2.root) it doesn’t show any error. But if I do that for a third .root file:

root [4] TFile f("file3.root"); root [5] TH1F *h3 = (TH1F*)f.Get("h3");

It shows the exact same error:

Error: Symbol f is not defined in current scope (tmpfile):1: Error: Failed to evaluate f.Get("h3") *** Interpreter error recovered ***

Any idea why this is happening?

couet · May 21, 2015, 9:05am

of course it is:

TFile f1(“file1.root”);
TH1F h1 = (TH1F)f.Get(“h1”);

TFile f2(“file2.root”);
TH1F h2 = (TH1F)f.Get(“h2”);

TFile f3(“file3.root”);
TH1F h3 = (TH1F)f.Get(“h3”);

radgs · May 21, 2015, 1:24pm

Oh, silly me…

Thank you.

radgs · May 21, 2015, 5:54pm

I am sorry but I am new to c++ and having some trouble with this task.

I am having an error when running the following code(by writing .x stackhist.cxx in root):

[code]#include “THStack.h”
#include “TSystem.h”
#include
#include “TFile.h”
#include “TTree.h”
#include “TH1D.h”
#include “TCanvas.h”
#include “TLegend.h”
#include “TRandom.h”

void stackhist(){
THStack *hs = new THStack(“hs”,“Histogramas pT(t)”);

TFile f1("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp1_2e3.root");
TH1F h1 = (TH1F)f.Get(“h1”);

TFile f2("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp1e3.root");
TH1F h2 = (TH1F)f.Get(“h2”);

TFile f3("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp7e2.root");
TH1F h3 = (TH1F)f.Get(“h3”);

TFile f4("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp1_2e3.root");
TH1F h4 = (TH1F)f.Get(“h4”);

TFile f5("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp1e3.root");
TH1F h5 = (TH1F)f.Get(“h5”);

TFile f6("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp7e2.root");
TH1F h6 = (TH1F)f.Get(“h6”);

hs->Add(h1);
hs->Add(h2);
hs->Add(h3);
hs->Add(h4);
hs->Add(h5);
hs->Add(h6);

hs->Draw(“ahiste2”);
}
[/code]

The error is the following:

root [4] .x stackhist.cxx Error: Symbol f is not defined in current scope stackhist.cxx:15: Error: Failed to evaluate f.Get("h1") *** Interpreter error recovered ***

Help?

Wile_E_Coyote · May 21, 2015, 6:12pm

[code]#include “TROOT.h”

// …

TFile f1("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp1_2e3.root");
TH1F h1 = (TH1F)f1.Get(“h1”); h1->SetDirectory(gROOT);

TFile f2("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp1e3.root");
TH1F h2 = (TH1F)f2.Get(“h2”); h2->SetDirectory(gROOT);

TFile f3("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp7e2.root");
TH1F h3 = (TH1F)f3.Get(“h3”); h3->SetDirectory(gROOT);

TFile f4("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp1_2e3.root");
TH1F h4 = (TH1F)f4.Get(“h4”); h4->SetDirectory(gROOT);

TFile f5("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp1e3.root");
TH1F h5 = (TH1F)f5.Get(“h5”); h5->SetDirectory(gROOT);

TFile f6("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp7e2.root");
TH1F h6 = (TH1F)f6.Get(“h6”); h6->SetDirectory(gROOT);[/code]

radgs · May 21, 2015, 8:39pm

When I do that, it gives me the following error:

root [0] Processing stackhist.cxx... Error: illegal pointer to class object h1 0x0 156 stackhist.cxx:16: *** Interpreter error recovered ***

pcanal · May 21, 2015, 8:58pm

Hi,

Then the file must not be containing any histogram named ‘h1’, at least not in the top level directory.

Cheers,
Philippe.

radgs · May 21, 2015, 9:22pm

Hi Philippe,

After entering root and getting the histograms into the ROOT Files directory by doing:

[code]TFile f1("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp1_2e3.root");
TH1F h1 = (TH1F)f1.Get(“h1”);

TFile f2("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp1e3.root");
TH1F h2 = (TH1F)f2.Get(“h2”);

(…)[/code]
And then by accessing TBrowser, I get all 6 root files each one with different histograms in ROOT Files (temporarily because if I close root they disappear). But the histograms inside each .root file are all named pt;1 (I’m not sure if is that you are talking about).

How do I copy them permanently to the main directory (that I suppose is ROOT Files…)?

radgs · May 21, 2015, 9:56pm

So, I wrote a code that works, but in the end it doesn’t show anything in the canvas c1…

Here’s my code:

[code]#include “THStack.h”
#include “TSystem.h”
#include
#include “TFile.h”
#include “TTree.h”
#include “TH1D.h”
#include “TCanvas.h”
#include “TLegend.h”
#include “TRandom.h”
#include “TROOT.h”

void stackhist(){
THStack *hs = new THStack(“hs”,“Histogramas pT(t)”);

TFile f1("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp1_2e3.root");
TH1F h1 = (TH1F)f1.Get(“h1”);

TFile f2("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp1e3.root");
TH1F h2 = (TH1F)f2.Get(“h2”);

TFile f3("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_13tev_mtp7e2.root");
TH1F h3 = (TH1F)f3.Get(“h3”);

TFile f4("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp1_2e3.root");
TH1F h4 = (TH1F)f4.Get(“h4”);

TFile f5("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp1e3.root");
TH1F h5 = (TH1F)f5.Get(“h5”);

TFile f6("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp7e2.root");
TH1F h6 = (TH1F)f6.Get(“h6”);

hs->Add(h1);
hs->Add(h2);
hs->Add(h3);
hs->Add(h4);
hs->Add(h5);
hs->Add(h6);

hs->Draw(“ahiste2”);
}[/code]

pcanal · May 22, 2015, 3:03am

Hi,

Indeed. Use eitherTFile *f4 = new TFile("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp1_2e3.root"); TH1F *h4 = (TH1F*)f4.Get("h4");orTFile f4("/home/jorge/madanalysis5/pp_TT_Zt/Build/pt_8tev_mtp1_2e3.root"); TH1F *h4 = (TH1F*)f4.Get("h4"); if (h4) h4->SetDirectory(0);The histogram are attached by default to their TFile and are deleted/close when the TFile object disappear. When I histogram is deleted, its representation in the canvas is also deleted.

Cheers,
Philippe.

Wile_E_Coyote · May 22, 2015, 6:18am

If all your histograms in all files are named “pt”, then you should use: TH1F *h1 = (TH1F*)f1.Get("pt"); h1->SetDirectory(0); TH1F *h2 = (TH1F*)f2.Get("pt"); h2->SetDirectory(0); TH1F *h3 = (TH1F*)f3.Get("pt"); h3->SetDirectory(0); TH1F *h4 = (TH1F*)f4.Get("pt"); h4->SetDirectory(0); TH1F *h5 = (TH1F*)f5.Get("pt"); h5->SetDirectory(0); TH1F *h6 = (TH1F*)f6.Get("pt"); h6->SetDirectory(0); or maybe better: TH1F *h1 = (TH1F*)(f1.Get("pt")->Clone("h1")); h1->SetDirectory(gROOT); TH1F *h2 = (TH1F*)(f2.Get("pt")->Clone("h2")); h2->SetDirectory(gROOT); TH1F *h3 = (TH1F*)(f3.Get("pt")->Clone("h3")); h3->SetDirectory(gROOT); TH1F *h4 = (TH1F*)(f4.Get("pt")->Clone("h4")); h4->SetDirectory(gROOT); TH1F *h5 = (TH1F*)(f5.Get("pt")->Clone("h5")); h5->SetDirectory(gROOT); TH1F *h6 = (TH1F*)(f6.Get("pt")->Clone("h6")); h6->SetDirectory(gROOT);

radgs · May 22, 2015, 4:03pm

Thank you for both replies. Now the code is fine and I can draw (and edit) the stacked histograms perfectly.

Jorge