Logo ROOT   6.12/06
Reference Guide
candleplotwhiskers.C File Reference
Tutorials » Histograms tutorials

Detailed Description

Example of candle plot showing the whiskers definition.

pict1_candleplotwhiskers.C.png
Processing /builddir/build/BUILD/root-6.12.06/tutorials/hist/candleplotwhiskers.C...
Q1 (-25%): -0.675525 Median: 0.00168511 Q3 (+25%): 0.676189
FCN=11.7941 FROM MIGRAD STATUS=CONVERGED 138 CALLS 139 TOTAL
EDM=1.08103e-12 STRATEGY= 1 ERROR MATRIX ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 Constant 3.72831e+03 1.82107e+02 4.21637e-02 1.36245e-08
2 Mean -1.10774e-01 7.20921e-02 8.42717e-06 -1.49401e-04
3 Sigma 9.59469e-01 2.51499e-02 2.82317e-06 5.37129e-04
FCN=8.04689 FROM MIGRAD STATUS=CONVERGED 139 CALLS 140 TOTAL
EDM=6.08152e-08 STRATEGY= 1 ERROR MATRIX ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 Constant 4.07186e+03 2.44580e+02 3.87026e-02 3.94837e-07
2 Mean -2.92179e-02 8.71835e-02 7.07837e-06 -2.13598e-02
3 Sigma 1.00971e+00 2.88317e-02 2.27510e-06 -1.25158e-01
FCN=6.93238 FROM MIGRAD STATUS=CONVERGED 106 CALLS 107 TOTAL
EDM=6.56099e-08 STRATEGY= 1 ERROR MATRIX ACCURATE
EXT PARAMETER STEP FIRST
NO. NAME VALUE ERROR SIZE DERIVATIVE
1 Constant 3.97002e+03 2.57596e+01 2.40433e-02 -9.00146e-06
2 Mean -1.89022e-04 1.18284e-02 1.62701e-05 7.29142e-03
3 Sigma 1.02465e+00 3.35469e-02 1.82218e-05 7.40149e-03
void candleplotwhiskers() {
TCanvas *c1 = new TCanvas("c1","Candle Presets",700,800);
c1->Divide(1,2);
TRandom *randnum = new TRandom();
TH2I *h1 = new TH2I("h1","Gaus",100,-5,5,1,0,1);
TH1I *h2 = new TH1I("h2","Gaus",100,-5,5);
h1->GetXaxis()->SetTitle("Standard deviation #sigma");
h2->GetXaxis()->SetTitle("Standard deviation #sigma");
h2->GetYaxis()->SetTitle("dN/d#sigma");
float myRand;
for (int i = 0; i < 100000; i++) {
myRand = randnum->Gaus(0,1);
h1->Fill(myRand,0);
h2->Fill(myRand);
}
Double_t *q = new Double_t[3];
Double_t *p = new Double_t[3];
q[0] = 0.; q[1] = 0.; q[2] = 0.;
p[0] = 0.25; p[1] = 0.5; p[2] = 0.75;
h2->GetQuantiles(3,q,p);
cout << "Q1 (-25%): " << q[0] << " Median: " << q[1] << " Q3 (+25%): " << q[2] << endl;
double iqr = q[2]-q[0];
TF1 *mygaus_1_middle = new TF1("mygaus_1_middle","gaus",q[0],q[2]);
TF1 *mygaus_1_left = new TF1("mygaus_1_left","gaus",q[0]-1.5*iqr,q[0]);
mygaus_1_left->SetLineColor(kGreen);
TF1 *mygaus_1_right = new TF1("mygaus_1_right","gaus",q[2],q[2]+1.5*iqr);
mygaus_1_right->SetLineColor(kGreen);
c1->cd(1);
h1->SetLineWidth(3);
h1->SetFillStyle(0);
h1->Draw("candley2 scat");
c1->cd(2);
h2->Draw("");
h2->Fit("mygaus_1_left","R");
mygaus_1_left->Draw("same");
TLine *l3 = new TLine(q[0]-1.5*iqr,0,q[0]-1.5*iqr,mygaus_1_left->Eval(q[0]-1.5*iqr));
l3->SetLineColor(kGreen); l3->SetLineWidth(2); l3->Draw("");
TLine *l1 = new TLine(q[0] ,0,q[0] ,mygaus_1_left->Eval(q[0]));
l1->SetLineWidth(2); l1->SetLineColor(kGreen); l1->Draw("");
h2->Fit("mygaus_1_right","R","");
mygaus_1_right->Draw("same");
TLine *l4 = new TLine(q[2]+1.5*iqr,0,q[2]+1.5*iqr,mygaus_1_left->Eval(q[2]+1.5*iqr));
l4->SetLineColor(kGreen); l4->SetLineWidth(2); l4->Draw("");
TLine *l5 = new TLine(q[2] ,0,q[2] ,mygaus_1_right->Eval(q[2]));
l5->SetLineWidth(2); l5->SetLineColor(kGreen); l5->Draw("");
h2->Fit("mygaus_1_middle","R");
mygaus_1_middle->Draw("same");
//In principal one could calculate these values by h2->Integral() as well
TText *t = new TText(); t->SetTextFont(42);
t->DrawText(0,mygaus_1_middle->Eval(0)/2,"50%");
t->DrawText(-1.5,mygaus_1_middle->Eval(-1.5)/2,"24.65%");
t->DrawText(+1,mygaus_1_middle->Eval(+1.5)/2,"24.65%");
t->DrawText(q[0]-1.5*iqr,1000,Form("%.3f",q[0]-1.5*iqr))->SetTextAngle(90);
t->DrawText(q[2]+1.5*iqr,1000,Form("%.3f",q[2]+1.5*iqr))->SetTextAngle(90);
t->DrawText(q[0],1000,Form("%.3f",q[0]))->SetTextAngle(90);
t->DrawText(q[2],1000,Form("%.3f",q[2]))->SetTextAngle(90);
}
Author
Georg Troska

Definition in file candleplotwhiskers.C.