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hist015_TH1_read_and_draw.C File Reference

Detailed Description

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Read a 1-D histogram from a ROOT File and draw it.

We attach (or generate) the ROOT file in $ROOTSYS/tutorials/hsimple.root or $PWD/hsimple.root We draw one histogram in different formats.

#include "TInterpreter.h"
#include "TCanvas.h"
#include "TSystem.h"
#include "TFile.h"
#include "TH2.h"
#include "TNtuple.h"
#include "TPaveLabel.h"
#include "TPaveText.h"
#include "TFrame.h"
#include "TSystem.h"
#include "TInterpreter.h"
{
// Fetch and open the hsimple.root File
TFile *example = TFile::Open(gROOT->GetTutorialDir() + "/hsimple.root");
example->ls(); // Show the file contents
// Get the histogram from the ROOT File
TH1 *hpx = nullptr; // pointer to base class TH1 is enough
example->GetObject("hpx", hpx);
TCanvas *c1 = new TCanvas("c1", "Histogram Drawing Options", 200, 10, 700, 900);
TPad *pad1 = new TPad("pad1", "The pad with the function", 0.03, 0.62, 0.50, 0.92);
TPad *pad2 = new TPad("pad2", "The pad with the histogram", 0.51, 0.62, 0.98, 0.92);
TPad *pad3 = new TPad("pad3", "The pad with the histogram", 0.03, 0.02, 0.97, 0.57);
pad1->Draw();
pad2->Draw();
pad3->Draw();
// Draw a global picture title
TPaveLabel *title = new TPaveLabel(0.1, 0.94, 0.9, 0.98, "Drawing options for one dimensional histograms");
title->SetTextFont(52);
title->Draw();
// Draw histogram hpx in first pad with the default option.
pad1->cd();
pad1->GetFrame()->SetFillColor(18);
hpx->SetFillColor(45);
hpx->DrawCopy();
TPaveLabel *label1 = new TPaveLabel(-3.5, 700, -1, 800, "Default option");
label1->Draw();
// Draw hpx as a lego. Clicking on the lego area will show
// a "transparent cube" to guide you rotating the lego in real time.
pad2->cd();
hpx->DrawCopy("lego1");
TPaveLabel *label2 = new TPaveLabel(-0.72, 0.74, -0.22, 0.88, "option Lego1");
label2->Draw();
TPaveLabel *label2a = new TPaveLabel(-0.93, -1.08, 0.25, -0.92, "Click on lego to rotate");
label2a->Draw();
// Draw hpx with its errors and a marker.
pad3->cd();
pad3->SetGridx();
pad3->SetGridy();
hpx->SetMarkerStyle(21);
hpx->Draw("e1p");
TPaveLabel *label3 = new TPaveLabel(2, 600, 3.5, 650, "option e1p");
label3->Draw();
// The following illustrates how to add comments using a PaveText.
// Attributes of text/lines/boxes added to a PaveText can be modified.
// The AddText function returns a pointer to the added object.
TPaveText *pave = new TPaveText(-3.78, 500, -1.2, 750);
TText *t1 = pave->AddText("You can move");
t1->SetTextColor(4);
t1->SetTextSize(0.05);
pave->AddText("Title and Stats pads");
pave->AddText("X and Y axis");
pave->AddText("You can modify bin contents");
pave->Draw();
c1->Update();
}
#define gROOT
Definition TROOT.h:406
virtual void SetTextFont(Font_t tfont=62)
Set the text font.
Definition TAttText.h:48
The Canvas class.
Definition TCanvas.h:23
A ROOT file is an on-disk file, usually with extension .root, that stores objects in a file-system-li...
Definition TFile.h:131
static TFile * Open(const char *name, Option_t *option="", const char *ftitle="", Int_t compress=ROOT::RCompressionSetting::EDefaults::kUseCompiledDefault, Int_t netopt=0)
Create / open a file.
Definition TFile.cxx:4130
TH1 is the base class of all histogram classes in ROOT.
Definition TH1.h:59
The most important graphics class in the ROOT system.
Definition TPad.h:28
A Pave (see TPave) with a text centered in the Pave.
Definition TPaveLabel.h:20
void Draw(Option_t *option="") override
Draw this pavelabel with its current attributes.
A Pave (see TPave) with text, lines or/and boxes inside.
Definition TPaveText.h:21
Base class for several text objects.
Definition TText.h:22
return c1
Definition legend1.C:41
auto * t1
Definition textangle.C:20
Date
August 2021
Author
Rene Brun

Definition in file hist015_TH1_read_and_draw.C.