Plotting data points

[jbmagallanes]

how do you plot two sets of data points with the same x-range (same values) but with different y-range? For example: {(0,5); (1,7); (2,10); (3,15)} and {(0,1000); (1,2000); (2,10000); (3,1500000)}. Thanks for your help.

[Wile_E_Coyote]

TMultiGraph

[ksmith]

import numpy as np
import ROOT

x = np.array([0,1,2,3], dtype='float64')
y1 = np.array([5,7,10,15], dtype='float64')
y2 = np.array([1000,2000,10000,1500000], dtype='float64')

g1 = ROOT.TGraph(len(x), x, y1)
g2 = ROOT.TGraph(len(x), x, y2)

mg = ROOT.TMultiGraph()
mg.Add(g1)
mg.Add(g2)

mg.Draw("AP")

[jbmagallanes]

thanks ksmith i will try to figure it out… i am actually doing two for-loops that give out two different values for the same x

[jbmagallanes]

it has this error:

error: no member named
’TMultiGraph’ in namespace 'ROOT’
mg = ROOT::TMultiGraph()

[ksmith]

What language are you using? Can you post a small example?

My example from above converted to C++

#include<array>                                                          
                                                                         
#include <TGraph.h>                                                      
#include <TMultiGraph.h>                                                 
                                                                         
{                                                                        
   std::array<Int_t, 4> x = {0,1,2,3};                                   
   std::array<Int_t, 4> yData1 = {5,7,10,15};                              
   std::array<Int_t, 4> yData2 = {1000,2000,10000,1500000};                              
                                                                         
   auto g1 = new TGraph(4, x.data(), yData1.data());                     
   auto g2 = new TGraph(4, x.data(), yData2.data());                     
                                                                         
   auto mg = new TMultiGraph();                                          
   mg->Add(g1);                                                          
   mg->Add(g2);                                                          
                                                                         
   mg->Draw("AP");                                                       
}

[jbmagallanes]

#include "TF1.h"
#include "Math/WrappedTF1.h"
#include "Math/GaussIntegrator.h"

void program002rootforum()
{
 int    N  = 20;
 double a  = 0.5;
 double m  = 1.0;
 double E  = 0.5;
 double s  = 1.0;
 double p  = m / (2.0*a);
 double q  = m / a;
 double xi = 0.0;
 double r  = m / (2.0*a);
 double w  = a / 2.0;
 double u  = m / (2.0*a);
 double v  = m / a;
 double xf = 2.0;
 double xd = (xf-xi) / N;

 g  = new TGraph();
 g1 = new TGraph();

 for(i=0; i<N; i++)
 {
  double x, y;

  x = xd * i;
  y = exp(x*x/2.0);
  g -> SetPoint (i, x, y);
  g -> SetMarkerStyle(28);
 }


 for(i=0; i<N; i++)
 {
  double x, y;

  x = xd * i;
  y = exp(-x*x/2.0) / (sqrt(sqrt(TMath::Pi())))*exp(-E*a*N);
  g1 -> SetPoint (i, x, y);
  g1 -> SetMarkerStyle(28);
 }

 mg = ROOT::TMultiGraph();
 mg.Add(g);
 mg.Add(g1);
 mg.Draw("AP");
}

[ksmith]

#include <TGraph.h>
#include <TMultiGraph.h>
//...
auto mg = new TMultiGraph();
mg->Add(g);
mg->Add(g1);
mg->Draw("AP");
//...

FYI:

Getting the same histograms after cuts

Remark on the way to post code snippets: When you post pieces of code on the forum enclose it with ``` . That makes your post much more readable (I systematically edit your posts that way) . So do: ``` // this is a C++ piece of code. ``` And it will display as: // this is a C++ piece of code.

[jbmagallanes]

thanks very much

your fyi is noted… i’m sorry…

[jbmagallanes]

It worked!!!

But there is another catch.
The y-values of “g1” are nearly visible because they are very small.
It makes only a horizontal line at the bottom.
The other graph is visible because its y-values are really large.
How do I scale the y-values of “g1” to make both graphs visible?

[ksmith]

@jbmagallanes

your fyi is noted… i’m sorry…

No worries, you’ll get better response with eay to read posts.

@jbmagallanes

The y-values of “g1” are nearly visible because they are very small.
It makes only a horizontal line at the bottom.
The other graph is visible because its y-values are really large.
How do I scale the y-values of “g1” to make both graphs visible?

Maybe log-axis?

gPad->SetLogy()

Or scale one of the sets of y-values:

scale = 1000;
y = exp(x*x/2.0) * scale;

[jbmagallanes]

thanks… i tried the “scale”

[jbmagallanes]

yes, tried it… but thanks

[couet]

void program002rootforum()
{
   int    N  = 20;
   double a  = 0.5;
   double m  = 1.0;
   double E  = 0.5;
   double s  = 1.0;
   double p  = m / (2.0*a);
   double q  = m / a;
   double xi = 0.0;
   double r  = m / (2.0*a);
   double w  = a / 2.0;
   double u  = m / (2.0*a);
   double v  = m / a;
   double xf = 2.0;
   double xd = (xf-xi) / N;

   TGraph *g  = new TGraph();
   TGraph *g1 = new TGraph();

   double x, y;
   int i;

   g->SetMarkerStyle(28);
   for (i=0; i<N; i++) {
      x = xd * i;
      y = exp(x*x/2.0);
      g->SetPoint (i, x, y);
   }


   g1 -> SetMarkerStyle(27);
   for (i=0; i<N; i++) {
      x = xd * i;
      y = exp(-x*x/2.0) / (sqrt(sqrt(TMath::Pi())))*exp(-E*a*N);
      g1 -> SetPoint (i, x, y);
   }

   TMultiGraph *mg = new TMultiGraph();
   mg->SetMinimum(0.0005);
   mg->Add(g);
   mg->Add(g1);
   mg->Draw("AP");
   gPad->SetLogy(1);
}