Plotting TGraphs on the same graph

[Harriet_Kumi]

Dear all,

I want to plot two graphs on the same plot. I have used this but its not plotting.

                                TGraph *gr1  = new TGraph(n,x1,y1);
                               TGraph *gr2  = new TGraph(n,x2,y2);
                               gr2->SetMarkerColor(2);
                               //gr2->SetMarkerStyle(21);

                               // create a multigraph and draw it
                               TMultiGraph  *mg  = new TMultiGraph();
                               mg->Add(gr1);
                               mg->Add(gr2);
                               mg->Draw("AP*");

so I used this option but it plots only one of the graphs.

 c2->cd(1);
                                // create the 1st TGraph
                               TGraph *gr1 = new TGraph(n,x1,y1);
                              // gr1->Draw("AP*");

                               // create the 2nd TGraph
                               TGraph *gr2 = new TGraph(n,x2,y2);
                               gr2->SetMarkerColor(2);
                               //gr2->Draw("AP*");


                               gr1->Draw("A*");
                               gr2->Draw("A*");

what should I do for two graphs to be on the same graph?

[couet]

@Harriet_Kumi

                                TGraph *gr1  = new TGraph(n,x1,y1);
                               TGraph *gr2  = new TGraph(n,x2,y2);
                               gr2->SetMarkerColor(2);
                               //gr2->SetMarkerStyle(21);

                               // create a multigraph and draw it
                               TMultiGraph  *mg  = new TMultiGraph();
                               mg->Add(gr1);
                               mg->Add(gr2);
                               mg->Draw("AP*");

This should work. Can you post a macro we can run? (the vectors are not defined in your code example).

[Harriet_Kumi]

yes please I tried this one as well but it didnt work. My macro uses a big data file in order for it to run that I cannot upload here. the thing is the two data has different axis as well. I do not know if I can upload image here for you to see that two graphs seperately

[Wile_E_Coyote]

A TMultiGraph should automatically compute the X and Y axis ranges to make all data points visible.

Another approach (not using a TMultiGraph):

Draw two graphs on one canvas with different Y scales

Hello. I have two data files and macro. And I need to draw two graphs on one canvas with different Y scales. I have read specific topic in ROOT manual, but unfortunately it hasn’t helped me. Can you help me please to solve this problem. Thank you. comp.C (1006 Bytes)

Superimposing two TGraphs with different ranges

Hello, I’m new in the ROOT community! …looking to the example of macro illustrating how to superimpose two histograms I was able to superimpose two TGraphs with different ranges and to draw a new Yaxis for the second one (see the png file attached). Now I would like to change: the plotTitle the color of the left axis title and add the axis title on the right (I was trying to do with SetTitle(“Rates [Hz]”) but it doesn’t work) how can I do it? I attach the code I used for it Superimpose_…

[couet]

{
   const int n = 10;
   double x1[n] = {0,1,2,3,4,5,6,7,8,9};
   double x2[n] = {0,-1,-2,-3,-4,-5,-6,-7,-8,-9};
   double y1[n] = {1,2,3,4,5,5,4,3,2,1};
   double y2[n] = {5,4,3,2,1,1,2,3,4,5};
   auto gr1  = new TGraph(n,x1,y1);
   gr1->SetMarkerColor(3);
   gr1->SetMarkerStyle(20);
   auto gr2  = new TGraph(n,x2,y2);
   gr2->SetMarkerColor(2);
   gr2->SetMarkerStyle(21);

   auto mg  = new TMultiGraph();
   mg->Add(gr1);
   mg->Add(gr2);
   mg->Draw("AP");
}

[Harriet_Kumi]

okay thank you it worked

[Harriet_Kumi]

thank you all it worked now

[Harriet_Kumi]

apparently, my supervisor does not the superimpose graph. We are looking for something like this

and the two graphs plotted on seperate graphs is this.

[Wile_E_Coyote]

mg->Draw("APC");

[couet]

@Harriet_Kumi

and the two graphs plotted on separate graphs is this.

In that case, you should divide your canvas in 2 subpad using Divide and draw each graph on a diffirend pad using cd. Do you know how or do you want an example?

[Harriet_Kumi]

yes please I want an example

[Wile_E_Coyote]

TCanvas *c = new TCanvas("c", "c");
c->Divide(1, 2); // (1, 2) ... or ... (2, 1)
c->cd(1); gr1->Draw("APC");
c->cd(2); gr2->Draw("APC");
c->cd(0);