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Reference Guide
hsum.C File Reference

Detailed Description

View in nbviewer Open in SWAN Histograms filled and drawn in a loop. Simple example illustrating how to use the C++ interpreter to fill histograms in a loop and show the graphics results

void hsum() {
TCanvas *c1 = new TCanvas("c1","The HSUM example",200,10,600,400);
c1->SetGrid();
gBenchmark->Start("hsum");
// Create some histograms.
auto total = new TH1F("total","This is the total distribution",100,-4,4);
auto main = new TH1F("main","Main contributor",100,-4,4);
auto s1 = new TH1F("s1","This is the first signal",100,-4,4);
auto s2 = new TH1F("s2","This is the second signal",100,-4,4);
total->Sumw2(); // store the sum of squares of weights
total->SetMarkerStyle(21);
total->SetMarkerSize(0.7);
main->SetFillColor(16);
s1->SetFillColor(42);
s2->SetFillColor(46);
TSlider *slider = 0;
// Fill histograms randomly
const Int_t kUPDATE = 500;
Float_t xs1, xs2, xmain;
for ( Int_t i=0; i<10000; i++) {
xmain = gRandom->Gaus(-1,1.5);
xs1 = gRandom->Gaus(-0.5,0.5);
xs2 = gRandom->Landau(1,0.15);
main->Fill(xmain);
s1->Fill(xs1,0.3);
s2->Fill(xs2,0.2);
total->Fill(xmain);
total->Fill(xs1,0.3);
total->Fill(xs2,0.2);
if (i && (i%kUPDATE) == 0) {
if (i == kUPDATE) {
total->Draw("e1p");
main->Draw("same");
s1->Draw("same");
s2->Draw("same");
c1->Update();
slider = new TSlider("slider",
"test",4.2,0,4.6,total->GetMaximum(),38);
slider->SetFillColor(46);
}
if (slider) slider->SetRange(0,Float_t(i)/10000.);
c1->Modified();
c1->Update();
}
}
slider->SetRange(0,1);
total->Draw("sameaxis"); // to redraw axis hidden by the fill area
c1->Modified();
gBenchmark->Show("hsum");
}
Author
Rene Brun

Definition in file hsum.C.

TRandom::Gaus
virtual Double_t Gaus(Double_t mean=0, Double_t sigma=1)
Samples a random number from the standard Normal (Gaussian) Distribution with the given mean and sigm...
Definition: TRandom.cxx:263
TBenchmark::Start
virtual void Start(const char *name)
Starts Benchmark with the specified name.
Definition: TBenchmark.cxx:172
hsum
Definition: hsum.py:1
Float_t
float Float_t
Definition: RtypesCore.h:57
Int_t
int Int_t
Definition: RtypesCore.h:45
total
static unsigned int total
Definition: TGWin32ProxyDefs.h:40
gBenchmark
R__EXTERN TBenchmark * gBenchmark
Definition: TBenchmark.h:59
s1
#define s1(x)
Definition: RSha256.hxx:109
main
int main(int argc, char **argv)
Definition: histspeedtest.cxx:751
gRandom
R__EXTERN TRandom * gRandom
Definition: TRandom.h:62
TRandom::SetSeed
virtual void SetSeed(ULong_t seed=0)
Set the random generator seed.
Definition: TRandom.cxx:597
TRandom::Landau
virtual Double_t Landau(Double_t mean=0, Double_t sigma=1)
Generate a random number following a Landau distribution with location parameter mu and scale paramet...
Definition: TRandom.cxx:369
TCanvas
Definition: TCanvas.h:23
TH1F
1-D histogram with a float per channel (see TH1 documentation)}
Definition: TH1.h:572
kUPDATE
@ kUPDATE
Definition: TFitParametersDialog.cxx:51
TSlider::SetRange
virtual void SetRange(Double_t xmin=0, Double_t xmax=1)
Set Slider range in [0,1].
Definition: TSlider.cxx:207
TBenchmark::Show
virtual void Show(const char *name)
Stops Benchmark name and Prints results.
Definition: TBenchmark.cxx:155
c1
return c1
Definition: legend1.C:41
TSlider
Definition: TSlider.h:18