fitslicesy¶

Illustrates how to use the TH1::FitSlicesY function It uses the TH2F histogram generated in macro hsimple.C It invokes FitSlicesY and draw the fitted "mean" and "sigma" in 2 sepate pads. This macro shows also how to annotate a picture, change some pad parameters.

Author: Rene Brun
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Monday, March 27, 2023 at 09:42 AM.

Change some default parameters in the current style

In [1]:

gStyle->SetLabelSize(0.06,"x");
gStyle->SetLabelSize(0.06,"y");
gStyle->SetFrameFillColor(38);
gStyle->SetTitleW(0.6);
gStyle->SetTitleH(0.1);

Connect the input file and get the 2-d histogram in memory

In [2]:

TString dir = gROOT->GetTutorialDir();
dir.Append("/hsimple.C");
dir.ReplaceAll("/./","/");
if (!gInterpreter->IsLoaded(dir.Data())) gInterpreter->LoadMacro(dir.Data());
TFile *hsimpleFile = (TFile*)gROOT->ProcessLineFast("hsimple(1)");
if (!hsimpleFile) return;
TH2F *hpxpy = (TH2F*)hsimpleFile->Get("hpxpy");

hsimple   : Real Time =   0.08 seconds Cpu Time =   0.08 seconds

Create a canvas and divide it

In [3]:

TCanvas *c1 = new TCanvas("c1","c1",700,500);
c1->SetFillColor(42);
c1->Divide(2,1);
TPad *leftPad = (TPad*)c1->cd(1);;
leftPad->Divide(1,2);

Warning in <TCanvas::Constructor>: Deleting canvas with same name: c1

Draw 2-d original histogram

In [4]:

leftPad->cd(1);
gPad->SetTopMargin(0.12);
gPad->SetFillColor(33);
hpxpy->Draw();
hpxpy->GetXaxis()->SetLabelSize(0.06);
hpxpy->GetYaxis()->SetLabelSize(0.06);
hpxpy->SetMarkerColor(kYellow);

Fit slices projected along Y fron bins in X [7,32] with more than 20 bins in Y filled

In [5]:

hpxpy->FitSlicesY(0,7,32,20);

Show fitted "mean" for each slice

In [6]:

leftPad->cd(2);
gPad->SetFillColor(33);
TH2F *hpxpy_0 = (TH2F*)hsimpleFile->Get("hpxpy_0");
hpxpy_0->Draw();
TPad *rightPad = (TPad*)c1->cd(2);
rightPad->Divide(1,2);
rightPad->cd(1);
gPad->SetTopMargin(0.12);
gPad->SetLeftMargin(0.15);
gPad->SetFillColor(33);
TH2F *hpxpy_1 = (TH2F*)hsimpleFile->Get("hpxpy_1");
hpxpy_1->Draw();

Show fitted "sigma" for each slice

In [7]:

rightPad->cd(2);
gPad->SetTopMargin(0.12);
gPad->SetLeftMargin(0.15);
gPad->SetFillColor(33);
TH2F *hpxpy_2 = (TH2F*)hsimpleFile->Get("hpxpy_2");
hpxpy_2->SetMinimum(0.8);
hpxpy_2->Draw();

attributes

In [8]:

hpxpy_0->SetLineColor(5);
hpxpy_1->SetLineColor(5);
hpxpy_2->SetLineColor(5);
hpxpy_0->SetMarkerColor(2);
hpxpy_1->SetMarkerColor(2);
hpxpy_2->SetMarkerColor(2);
hpxpy_0->SetMarkerStyle(21);
hpxpy_1->SetMarkerStyle(21);
hpxpy_2->SetMarkerStyle(21);
hpxpy_0->SetMarkerSize(0.6);
hpxpy_1->SetMarkerSize(0.6);
hpxpy_2->SetMarkerSize(0.6);

Draw all canvases

In [9]:

%jsroot on
gROOT->GetListOfCanvases()->Draw()