Turn off frame of TGraph

ROOT
1

Hello,

I’d like to plot a TGraph without a frame or axes. I found how to do the latter, but not the former.

Thanks for any help,
Roger

ROOT 5.34/10 (heads/v5-34-00-patches@v5-34-10-5-g0e8bac8, Sep 04 2013, 11:52:19 on linuxx8664gcc)

2 
root [0]  TCanvas *c = new TCanvas();
root [1]  c->Range(-10.,-10,10,10);
root [2]  TGraph *g = new TGraph();
root [3]  g->SetPoint(0,-5,-5);
root [4]  g->SetPoint(1,0,0);
root [5]  g->SetPoint(2,5,1);
root [6]  g->Draw("l")
3

Hello Olivier,

Thanks for your reply.

I tried your solution but get no output from the attached code:

#include "TCanvas.h"
#include "TLine.h"
#include "TAxis.h"
#include "TF1.h"
#include "TMath.h"
#include "TGraph.h"
#include "TCurlyLine.h"
#include "TArrow.h"
#include "TLatex.h"

Int_t npeaks = 1;
Int_t npx    = 1000;
Double_t peaks(Double_t *x, Double_t *par) {
   Double_t result = 0.0;
   for (Int_t p=0;p<npeaks;p++) {
      Double_t norm  = par[3*p+0];
      Double_t mean  = par[3*p+1];
      Double_t sigma = par[3*p+2];
      result += norm*TMath::BreitWigner(x[0],mean,sigma);
   }
   return result;
}

Int_t twaddle(){
  TCanvas *c = new TCanvas("c","Absorption-emission",700,550);
  //  c->Divide(2,1);		// columns,rows

  Double_t *par = new Double_t[3*npeaks];
  Double_t xmin = 0;
  Double_t xmax = 10;
  par[0] = 2.0;
  par[1] = 6.0;
  par[2] = 0.1;

  TF1 *emission = new TF1("emission",peaks,xmin,xmax,3*npeaks);
  emission->SetNpx(npx);
  emission->SetParameters(par);
  //  emission->Draw();

  // Fill arrays and plot a TGraph 
  // (TF1 cannot be rotated, apparently).
  Double_t *x = new Double_t[npx];
  Double_t *y = new Double_t[npx];
  for (Int_t i = 0; i < npx; i++) {
    x[i] = xmin + i*(xmax-xmin)/npx;
    y[i] = emission->Eval(x[i]);
  }
  TGraph *g = new TGraph(npx,y,x);
  g->SetLineWidth(2);
  g->SetLineColor(50);
  g->SetTitle("");
  //  c->cd(2);

  g->Draw("l");
  g->GetXaxis()->SetNdivisions(0);
  g->GetYaxis()->SetNdivisions(0);
  c->SetSelected(c);
  c->Modified();

  return 0;
}

If I call g->Draw() instead of g->Draw(“l”), I get a plot.

Cheers,
Roger

4

Hi Roger,

But you are not doing what I told you.
You are not setting the range.

#include "TCanvas.h"
#include "TLine.h"
#include "TAxis.h"
#include "TF1.h"
#include "TMath.h"
#include "TGraph.h"
#include "TCurlyLine.h"
#include "TArrow.h"
#include "TLatex.h"

Int_t npeaks = 1;
Int_t npx    = 1000;
Double_t peaks(Double_t *x, Double_t *par) {
   Double_t result = 0.0;
   for (Int_t p=0;p<npeaks;p++) {
      Double_t norm  = par[3*p+0];
      Double_t mean  = par[3*p+1];
      Double_t sigma = par[3*p+2];
      result += norm*TMath::BreitWigner(x[0],mean,sigma);
   }
   return result;
}

void twaddle(){
  TCanvas *c = new TCanvas("c","Absorption-emission",700,550);
  c->Range(0.,0.,14,11); // <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

  Double_t *par = new Double_t[3*npeaks];
  Double_t xmin = 0;
  Double_t xmax = 10;
  par[0] = 2.0;
  par[1] = 6.0;
  par[2] = 0.1;

  TF1 *emission = new TF1("emission",peaks,xmin,xmax,3*npeaks);
  emission->SetNpx(npx);
  emission->SetParameters(par);

  // Fill arrays and plot a TGraph 
  // (TF1 cannot be rotated, apparently).
  Double_t *x = new Double_t[npx];
  Double_t *y = new Double_t[npx];
  for (Int_t i = 0; i < npx; i++) {
    x[i] = xmin + i*(xmax-xmin)/npx;
    y[i] = emission->Eval(x[i]);
  }
  TGraph *g = new TGraph(npx,y,x);
  g->SetLineWidth(2);
  g->SetLineColor(50);
  g->SetTitle("");
  //  c->cd(2);

  g->Draw("l");
  g->GetXaxis()->SetNdivisions(0);
  g->GetYaxis()->SetNdivisions(0);
  c->SetSelected(c);
  c->Modified();
}

Cheers,
Olivier

5

Thanks Olivier. I should have paid closer attention.

Roger