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Reference Guide
h1ReadAndDraw.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);
// Draw a global picture title
TPaveLabel *title = new TPaveLabel(0.1,0.94,0.9,0.98,
"Drawing options for one dimensional histograms");
// Draw histogram hpx in first pad with the default option.
TPaveLabel *label1 = new TPaveLabel(-3.5,700,-1,800,"Default option");
// Draw hpx as a lego. Clicking on the lego area will show
// a "transparent cube" to guide you rotating the lego in real time.
TPaveLabel *label2 = new TPaveLabel(-0.72,0.74,-0.22,0.88,"option Lego1");
TPaveLabel *label2a = new TPaveLabel(-0.93,-1.08,0.25,-0.92,
"Click on lego to rotate");
// Draw hpx with its errors and a marker.
TPaveLabel *label3 = new TPaveLabel(2,600,3.5,650,"option e1p");
// 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");
pave->AddText("Title and Stats pads");
pave->AddText("X and Y axis");
pave->AddText("You can modify bin contents");
#define gROOT
Definition: TROOT.h:405
virtual void SetFillColor(Color_t fcolor)
Set the fill area color.
Definition: TAttFill.h:37
virtual void SetMarkerStyle(Style_t mstyle=1)
Set the marker style.
Definition: TAttMarker.h:40
virtual void SetTextFont(Font_t tfont=62)
Set the text font.
Definition: TAttText.h:46
The Canvas class.
Definition: TCanvas.h:23
A ROOT file is a suite of consecutive data records (TKey instances) with a well defined format.
Definition: TFile.h:54
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:4053
TH1 is the base class of all histogram classes in ROOT.
Definition: TH1.h:58
void Draw(Option_t *option="") override
Draw this histogram with options.
Definition: TH1.cxx:3060
virtual TH1 * DrawCopy(Option_t *option="", const char *name_postfix="_copy") const
Copy this histogram and Draw in the current pad.
Definition: TH1.cxx:3107
The most important graphics class in the ROOT system.
Definition: TPad.h:28
void SetGridx(Int_t value=1) override
Definition: TPad.h:331
void SetGridy(Int_t value=1) override
Definition: TPad.h:332
TVirtualPad * cd(Int_t subpadnumber=0) override
Set Current pad.
Definition: TPad.cxx:597
TFrame * GetFrame() override
Get frame.
Definition: TPad.cxx:2831
void Draw(Option_t *option="") override
Draw Pad in Current pad (re-parent pad if necessary).
Definition: TPad.cxx:1268
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.
Definition: TPaveLabel.cxx:87
A Pave (see TPave) with text, lines or/and boxes inside.
Definition: TPaveText.h:21
virtual TText * AddText(Double_t x1, Double_t y1, const char *label)
Add a new Text line to this pavetext at given coordinates.
Definition: TPaveText.cxx:189
void Draw(Option_t *option="") override
Draw this pavetext with its current attributes.
Definition: TPaveText.cxx:240
Base class for several text objects.
Definition: TText.h:22
return c1
Definition: legend1.C:41
auto * t1
Definition: textangle.C:20
Rene Brun

Definition in file h1ReadAndDraw.C.