# Drawing different Uncertainty Bands

Dear experts,

I am trying to compare different MCs with data and draw two types of uncertainty bands (statistical and total) in the ratio plot.

I am attaching a screenshot for the reference. I am looking for a similar kind of plot.

I have already separated statistical and total uncertainty. So, I have two histograms of data with the same content but with different uncertainty. So, what is the way to draw different MCs and data in the upper pad and their ratio in the lower pad with different uncertainty bands?

Any working examples and any suggestions will be of great help.

Regards,

To divide the canvas:
https://root.cern/doc/master/canvas2_8C.html
To superpose the histograms, it’s easier to add them to a THStack (and draw the THStack with the option “nostack”):
https://root.cern/doc/master/classTHStack.html
To draw with error bars, you can use the option “e2”
https://root.cern/doc/master/classTHistPainter.html#HP09
You will also need to set the fill colours and fill styles for the histograms (see TAttFill).

To draw any histo with a visible marker, you can use

``````histo->SetMarkerStyle(20);  // filled circles
histo->SetMarkerSize(1);  //  experiment with other float values
``````

And to draw histos with error bars, lines and markers, you can add them twice to the THStack (once with the option “e”, and once with the option “e2”); e.g.

``````{
TH1F *h=new TH1F("h","h",4,0,4);
THStack *hs=new THStack();
for (int i=1;i<5;++i) {
h->SetBinContent(i,5-i);
h->SetBinError(i,0.5*(i));
}
hs->SetMinimum(0);
hs->SetMaximum(10);
h->SetMarkerStyle(20);
h->SetMarkerSize(1.3);
h->SetLineColor(4);
h->SetFillColor(4);
h->SetFillStyle(3001);
hs->Draw("nostack");
}
``````

I have 2 Data histograms having the same content but with one statistical error and the other with systematic error.
Now, in the upper pad, I want to plot one data histogram with different MC histogram. I want to make the ratio of MCs with Data in the lower pad and draw the two uncertainty bands: one statistical and the other systematic band.

So, if I plot two 2 data histograms and other MCs in the upper pad and the ratio in the lower pad, I can plot two different uncertainty bands from the 2 data histograms. But I want one data histogram in the upper pad, just as shown in the screenshot.

Requirement:

1. One data histogram and other MCs in the upper pad
2. Ratio of Data with different MCs and two different uncertainty bands in the lower pad.

N.B. I am not concerned with dividing the canvas or ratio of the histograms but with how I can draw two different uncertainty bands.

May be you can provide a macro showing what you already have ?

Dear experts,

I have figured out most of the parts. But I am a bit struggling with the drawing options.
Please suggest how I can do the plotting style I have posted in the first message.

Basically, I want

1. For Data → Marker+Filled Error bar in the upper pad
2. For MC → Line+Hatched Error bar in the upper and lower pad

This is the macro I have. And please suggest if there are any other ways to do this. And I want to use TH1D not THStack.

``````#include <TCanvas.h>
#include <TH1D.h>
#include <TRandom.h>

void ErrorPlot() {

TRandom3 randGen;

TCanvas* canvas = new TCanvas("canvas", "Three Histograms", 800, 600);

TH1D* hist1 = new TH1D("hist1", "Data", 10, -5, 5); //Data
TH1D* hist2 = new TH1D("hist2", "Stat Errors", 10, 0, 10);    //Stat
TH1D* hist3 = new TH1D("hist3", "Total Errors", 10, 0, 10);   //Tot
TH1D* hist4 = new TH1D("hist4", "Central Values with Stat Errors", 10, -5, 5); //DataStat
TH1D* hist5 = new TH1D("hist5", "Central Values with Total Errors", 10, -5, 5); //DataTot
TH1D* hist6 = new TH1D("hist6", "MC", 10, -5, 5); //MC

for (int i = 0; i < 10000; i++) {
double value1 = randGen.Gaus(0.0, 1.0);
hist1->Fill(value1);
}

/*
for(int i=1; i<=hist1->GetNbinsX(); i++){
cout<<"his1 : "<<hist1->GetBinError(i)<<endl;
}
*/

for (int i = 1; i <= 10; ++i) {
hist2->SetBinContent(i,0.5*i);
hist3->SetBinContent(i,1.5*i);
//cout<<"hist2 Bin Content: "<<hist2->GetBinContent(i)<<endl;
//cout<<"hist3 Bin Content: "<<hist3->GetBinContent(i)<<endl;
}

for (int i = 1; i <= 10; ++i) {
double centralValue1 = hist1->GetBinContent(i);
double error2 = hist2->GetBinContent(i);
double error3 = hist3->GetBinContent(i);

hist4->SetBinContent(i, centralValue1); hist4->SetBinError(i, error2);
hist5->SetBinContent(i, centralValue1); hist5->SetBinError(i, error3);
//cout<<"hist4 Bin Error : "<<hist4->GetBinError(i)<<endl;
//cout<<"hist5 Bin Error : "<<hist5->GetBinError(i)<<endl;
}

for (int i = 0; i < 20000; i++) {
double value6 = randGen.Gaus(0.0, 1.0);
hist6->Fill(value6);
}

TH1D *hist1_v1 = (TH1D*)hist1->Clone();
TH1D *hist4_v1 = (TH1D*)hist4->Clone();
TH1D *hist5_v1 = (TH1D*)hist5->Clone();
TH1D *hist6_v1 = (TH1D*)hist6->Clone();

hist1_v1->Scale(1/hist1_v1->Integral());
hist4_v1->Scale(1/hist4_v1->Integral());
hist5_v1->Scale(1/hist5_v1->Integral());
hist6_v1->Scale(1/hist6_v1->Integral());

gStyle->SetOptStat(0);

hist1_v1->SetTitle("");
hist1_v1->SetMarkerStyle(20);
hist1_v1->SetMarkerSize(1);
hist1_v1->SetLineColor(kBlue);
hist1_v1->SetFillColor(kYellow);
hist1_v1->Draw("e2");

//hist6_v1->SetMarkerStyle(20);
//hist6_v1->SetMarkerColor(kRed);
//hist6_v1->SetMarkerSize(0);
hist6_v1->SetLineColor(kRed);
hist6_v1->SetFillColor(kRed);
hist6_v1->SetFillStyle(3001);
hist6_v1->Draw("same e2");   //drawing option line required with hatched error bar

hist4_v1->SetLineColor(kGray);
hist4_v1->SetFillColor(kGray);
hist5_v1->SetLineColor(kYellow);
hist5_v1->SetFillColor(kYellow);

TLegend* legend1 = new TLegend(.7,0.7,0.88,0.88);
legend1->SetBorderSize(0);
legend1->Draw();

canvas->cd();

TH1D* hist6_v2 = (TH1D*)hist6->Clone();
hist6_v2->Scale(1/hist6_v2->Integral());

TH1* ratio = (TH1*)hist6_v2->Clone();
TH1* Stat = (TH1*)hist6_v2->Clone();
TH1* Tot = (TH1*)hist6_v2->Clone();

ratio->Divide(hist1_v1);
Stat->Divide(hist4_v1);
Tot->Divide(hist5_v1);

Tot->SetFillColor(kYellow);
Tot->Draw("e2");

Stat->SetFillColor(kGray);
Stat->Draw("same e2");

ratio->SetLineColor(kRed);
//ratio->SetFillColor(kRed);
//ratio->SetFillStyle(3001);
ratio->Draw("same hist");

Tot->SetTitle("");
Tot->SetMinimum(0.0);
Tot->SetMaximum(2.0);
Tot->SetStats(0);

Tot->GetXaxis()->SetTitleSize(0.13);
Tot->GetXaxis()->SetTitleOffset(1.15);
Tot->GetXaxis()->SetLabelSize(0.1);
Tot->GetXaxis()->CenterTitle();

Tot->GetYaxis()->SetTitle("MC/Data");
Tot->GetYaxis()->CenterTitle();
Tot->GetYaxis()->SetNdivisions(505);
Tot->GetYaxis()->SetTitleSize(0.12);
Tot->GetYaxis()->SetTitleOffset(0.35);
Tot->GetYaxis()->SetLabelSize(0.09);

TLine* line_v1 = new TLine(hist1_v1->GetXaxis()->GetXmin(), 1, hist1_v1->GetXaxis()->GetXmax(), 1);
line_v1->SetLineStyle(2);
line_v1->Draw();

canvas->SaveAs("ErrorPlot.pdf");
}
``````

Regards.

``````#include <TCanvas.h>
#include <TH1D.h>
#include <TRandom.h>

void ErrorPlot() {

TRandom3 randGen;

TCanvas* canvas = new TCanvas("canvas", "Three Histograms", 800, 600);

TH1D* hist1 = new TH1D("hist1", "Data", 10, -5, 5); //Data
TH1D* hist2 = new TH1D("hist2", "Stat Errors", 10, 0, 10);    //Stat
TH1D* hist3 = new TH1D("hist3", "Total Errors", 10, 0, 10);   //Tot
TH1D* hist4 = new TH1D("hist4", "Central Values with Stat Errors", 10, -5, 5); //DataStat
TH1D* hist5 = new TH1D("hist5", "Central Values with Total Errors", 10, -5, 5); //DataTot
TH1D* hist6 = new TH1D("hist6", "MC", 10, -5, 5); //MC

for (int i = 0; i < 10000; i++) {
double value1 = randGen.Gaus(0.0, 1.0);
hist1->Fill(value1);
}

for (int i = 1; i <= 10; ++i) {
hist2->SetBinContent(i,0.5*i);
hist3->SetBinContent(i,1.5*i);
}

for (int i = 1; i <= 10; ++i) {
double centralValue1 = hist1->GetBinContent(i);
double error2 = hist2->GetBinContent(i);
double error3 = hist3->GetBinContent(i);
hist4->SetBinContent(i, centralValue1); hist4->SetBinError(i, error2);
hist5->SetBinContent(i, centralValue1); hist5->SetBinError(i, error3);
}

for (int i = 0; i < 20000; i++) {
double value6 = randGen.Gaus(0.0, 1.0);
hist6->Fill(value6);
}

TH1D *hist1_v1 = (TH1D*)hist1->Clone();
TH1D *hist4_v1 = (TH1D*)hist4->Clone();
TH1D *hist5_v1 = (TH1D*)hist5->Clone();
TH1D *hist6_v1 = (TH1D*)hist6->Clone();

hist1_v1->Scale(1/hist1_v1->Integral());
hist4_v1->Scale(1/hist4_v1->Integral());
hist5_v1->Scale(1/hist5_v1->Integral());
hist6_v1->Scale(1/hist6_v1->Integral());

gStyle->SetOptStat(0);

hist1_v1->SetTitle("");
hist1_v1->SetMarkerStyle(20);
hist1_v1->SetMarkerSize(1);
hist1_v1->SetLineColor(kBlue);
hist1_v1->SetFillColor(kYellow);
hist1_v1->Draw("e2");

hist6_v1->SetLineColor(kRed);
hist6_v1->SetFillColor(kRed);
hist6_v1->SetFillStyle(3004);
hist6_v1->Draw("same e2");   //drawing option line required with hatched error bar
TH1D *hist6_v11 = (TH1D *)(hist6_v1->DrawCopy("same hist"));
hist6_v11->SetFillStyle(0);

hist4_v1->SetLineColor(kGray);
hist4_v1->SetFillColor(kGray);
hist5_v1->SetLineColor(kYellow);
hist5_v1->SetFillColor(kYellow);

TLegend* legend1 = new TLegend(.7,0.7,0.88,0.88);
legend1->SetBorderSize(0);
legend1->Draw();

canvas->cd();

TH1D* hist6_v2 = (TH1D*)hist6->Clone();
hist6_v2->Scale(1/hist6_v2->Integral());

TH1* ratio = (TH1*)hist6_v2->Clone();
TH1* Stat = (TH1*)hist6_v2->Clone();
TH1* Tot = (TH1*)hist6_v2->Clone();

ratio->Divide(hist1_v1);
Stat->Divide(hist4_v1);
Tot->Divide(hist5_v1);

Tot->SetFillColor(kYellow);
Tot->Draw("e2");

Stat->SetFillColor(kGray);
Stat->Draw("same e2");

ratio->SetLineColor(kRed);
ratio->Draw("same hist");

Tot->SetTitle("");
Tot->SetMinimum(0.0);
Tot->SetMaximum(2.0);
Tot->SetStats(0);

Tot->GetXaxis()->SetTitleSize(0.13);
Tot->GetXaxis()->SetTitleOffset(1.15);
Tot->GetXaxis()->SetLabelSize(0.1);
Tot->GetXaxis()->CenterTitle();

Tot->GetYaxis()->SetTitle("MC/Data");
Tot->GetYaxis()->CenterTitle();
Tot->GetYaxis()->SetNdivisions(505);
Tot->GetYaxis()->SetTitleSize(0.12);
Tot->GetYaxis()->SetTitleOffset(0.35);
Tot->GetYaxis()->SetLabelSize(0.09);

TLine* line_v1 = new TLine(hist1_v1->GetXaxis()->GetXmin(), 1, hist1_v1->GetXaxis()->GetXmax(), 1);
line_v1->SetLineStyle(2);
line_v1->Draw();

canvas->SaveAs("ErrorPlot.pdf");
}
``````

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