Ratio plot

ROOT
1

Hi, I used this example root.cern.ch/root/html/tutorial … lot.C.html to draw 2 th1f and their ratio. The macro is in the attachment; Unfortunatly…there are some problems because:

  1. It looks like to me that the ratio isn’t right in the ranges, because in the range 20-30 Km I think it must be greather than the values plotted by root…
    2)i t doesn’t the plot the legend:
  2. it doesn’t write the numbers of y axis of first graph
  3. the number “15” of y axis of the second graph is cutted.

thanks
hfirstint.c (4.65 KB)

2

I can have a look at your problem but I just want to mention that we have developed a new class call TRatioPlot to deal with all these Issues. It has just been put in the ROOT master:

root.cern.ch/doc/master/classTRatioPlot.html

3

I am missing your ROOT files in order to run your macro.

4

hi couet, i copied this code

void ratioplot1() { gStyle->SetOptStat(0); auto c1 = new TCanvas("c1", "A ratio example"); auto h1 = new TH1D("h1", "h1", 50, 0, 10); auto h2 = new TH1D("h2", "h2", 50, 0, 10); auto f1 = new TF1("f1", "exp(- x/[0] )"); f1->SetParameter(0, 3); h1->FillRandom("f1", 1900); h2->FillRandom("f1", 2000); h1->Sumw2(); h2->Scale(1.9 / 2.); h1->GetXaxis()->SetTitle("x"); h1->GetYaxis()->SetTitle("y"); auto rp = new TRatioPlot(h1, h2); c1->SetTicks(0, 1); rp->Draw(); c1->Update(); }

to try the macro, but when I compile I’ve this error:

mybe, doesn’t it work using ROOT 5.34.36?

EDIT:
Here the link to download the root files

drive.google.com/file/d/0B9Me0x … sp=sharing
drive.google.com/file/d/0B9Me0x … sp=sharing

5

as I said the TRatioPLot class is available only in ROOT 6.08… you are using ROOT 5 …

I will take our files.

6

[quote=“couet”]as I said the TRatioPLot class is available only in ROOT 6.08… you are using ROOT 5 …

I will take our files.[/quote]
Unfortunatly, using Windows, I can’t download ROOT 6.08…

7

In your macro the variable “hene” is not declared and not initialized … what is it supposed to be ?

8

Hi couet…copying the code by other my macro, i forgot to change the name from “hene” to hfirstint"…but…it is just for the control if there is the histogram in the root file…it doesn’t give problem iduring compiling

9 
#include "TFile.h"
#include "TCanvas.h"
#include "TStyle.h"
#include "TH1.h"
#include "TH2.h"
#include "TH3.h"
#include "TGaxis.h"
#include "TRandom.h"
#include "TLegend.h"
#include "TPaveStats.h"
#include "TGraph.h"

void hfirstint()
{
   gROOT->SetBatch(1);

   TFile *g = TFile::Open("cors_plot-gammatot.root");
   if (g == 0) {
      // if we cannot open the file, print an error message and return immediatly
      printf("Error: cannot open cors_plot.root!\n");
      return;
   }

   TFile *p = TFile::Open("cors_plot-prottot.root");
   if (p == 0) {
      // if we cannot open the file, print an error message and return immediatly
      printf("Error: cannot open cors_plot.root!\n");
      return;
   }

   TH1F *hfirstintg = (TH1F *)g->Get("hfirstint");
   if (hfirstintg == 0) {
      printf("Error getting an histogram from the file!\n");
      return;
   }

   TH1F *hfirstintp = (TH1F *)p->Get("hfirstint");
   if (hfirstintp == 0) {
      printf("Error getting an histogram from the file!\n");
      return;
   }

   float offx=1.2;
   float offy=1;
   float marg=0.15;
   TCanvas *c2 = new TCanvas("c2","hists with different scales",1280,1024);
   TPad *pad1  = new TPad("pad1", "pad1", 0, 0.3, 1, 1.0);
   pad1->SetBottomMargin(0); // Upper and lower plot are joined
   pad1->SetGridx();         // Vertical grid
   pad1->Draw();             // Draw the upper pad: pad1
   pad1->cd();               // pad1 becomes the current pad

   hfirstintg->SetLineColor(kBlack);
   hfirstintg->SetTitle("Quota di prima interazione dei #gamma e #font[12]{p} primari");
   hfirstintg->GetXaxis()->SetTitle("Altezza (Km)");
   hfirstintg->GetYaxis()->SetTitle("N_{part}");
   hfirstintg->GetYaxis()->SetTitleOffset(offy);
   hfirstintg->SetMinimum(0.001);
   c2->SetLeftMargin(marg);
   hfirstintg->GetYaxis()->SetTitleSize(20);
   hfirstintg->GetYaxis()->SetTitleFont(43);
   hfirstintg->GetYaxis()->SetTitleOffset(1.55);
   hfirstintg->GetYaxis()->SetLabelFont(43); // Absolute font size in pixel (precision 3)
   hfirstintg->GetYaxis()->SetLabelSize(15);
   hfirstintg->Draw();
   hfirstintp->SetLineColor(kBlue);
   hfirstintp->Draw("sames");
   gPad->Update();

   // Define the ratio plot
   TLegend *leg = new TLegend(0.5,0.67,0.6,0.88,NULL,"brNDC");
   leg->AddEntry(hfirstintg, "#gamma", "l");
   leg->AddEntry(hfirstintp, "#font[12]{p}", "l");
   leg->Draw();

   c2->cd();          // Go back to the main canvas before defining pad2
   TPad *pad2 = new TPad("pad2", "pad2", 0, 0.05, 1, 0.3);
   pad2->SetTopMargin(0);
   pad2->SetBottomMargin(0.2);
   pad2->SetGridx(); // vertical grid
   pad2->Draw();
   pad2->cd();       // pad2 becomes the current pad
   c2->Update();

   TPaveStats *stats1 = (TPaveStats*)hfirstintg->GetListOfFunctions()->FindObject("stats");
   TPaveStats *stats2 = (TPaveStats*)hfirstintp->GetListOfFunctions()->FindObject("stats");
   stats1->SetTextColor(kBlack);
   stats2->SetTextColor(kBlue);
   stats1->SetX1NDC(0.80); stats1->SetX2NDC(0.98);
   stats1->SetY1NDC(0.79); stats1->SetY2NDC(0.94);
   stats2->SetX1NDC(0.80); stats2->SetX2NDC(0.98);
   stats2->SetY1NDC(0.62); stats2->SetY2NDC(0.77);
   gPad->Modified();
   gPad->Update();

   TH1F *h3 = (TH1F*)hfirstintg->Clone("h3");
   h3->SetLineColor(kBlack);
   h3->SetMinimum(0);  // Define Y ..
   h3->SetMaximum(15.); // .. range
   h3->Sumw2();
   h3->SetStats(0);      // No statistics on lower plot
   h3->Divide(hfirstintp);
   h3->SetMarkerStyle(21);
   h3->SetMaximum(15.5);
   h3->SetTitle(""); // Remove the ratio title
   h3->Draw("ep");       // Draw the ratio plot

   // Y axis ratio plot settings
   h3->GetYaxis()->SetTitle("h_{#gamma}/h_{p} ");
   h3->GetYaxis()->SetNdivisions(505);
   h3->GetYaxis()->SetTitleSize(20);
   h3->GetYaxis()->SetTitleFont(43);
   h3->GetYaxis()->SetTitleOffset(1.55);
   h3->GetYaxis()->SetLabelFont(43); // Absolute font size in pixel (precision 3)
   h3->GetYaxis()->SetLabelSize(15);

   // X axis ratio plot settings
   h3->GetXaxis()->SetTitleSize(20);
   h3->GetXaxis()->SetTitleFont(43);
   h3->GetXaxis()->SetTitleOffset(4.);
   h3->GetXaxis()->SetLabelFont(43); // Absolute font size in pixel (precision 3)
   h3->GetXaxis()->SetLabelSize(15);

   c2->Print("c2.pdf");
}
10

Hi couet thanks! other question please… i wrote

h3->SetMarkerColor(kRed);

to have the ratio plot in red color…but i see there is something in black…what is it?

11

h3 is plotted with errors bars. The markers and the bars can have different colors.
To have all red you should do:

h3->SetMarkerColor(kRed);
h3->SetLineColor(kRed);
1 Like
12

Thanks couet!