An example of histogramming, with a fit and a spectrum

{
// This example plots a vector and accumulates a histogram of the values
// of this vector. It also plots a spectrum of the interesting part.
// Only the part of the vector that corresponds to the interesting part
// are plotted (a peak at the beginning of the frames)
// The histogram is accumulated for nframmax frames
// To see the result of this macro, click  here 

   gROOT->Reset();

   gBenchmark->Start("scroll2spectrum");

   FrameH* fr;  // not mandatory to declare in a script

// Max number of frames displayed
   Int_t nframmax = 14;

// Open a new window (canvas) and divide it in 3
// Add some fancy enhancements
   c1 = new TCanvas("c1","c1",1);
   c1->Divide(2,1);
   c1_1->SetFillColor(44);
   c1_1->SetFrameFillColor(41);
// Divide the second pad by 2 so as to obtain a 3 pads canvas
   c1_2->Divide(1,2);
   c1_2->cd(1);  // Go to the first subpad of the second (c1_2) pad
// gPad is always the current selected pad
   gPad->SetFillColor(44);
   gPad->SetFrameFillColor(41);
   gPad->SetLogy();
   gPad->SetGridx();
   gPad->SetGridy();
   c1_2->cd(2);  // Go to the second subpad of the second (c1_2) pad
// gPad is always the current selected pad
   gPad->SetFillColor(44);
   gPad->SetFrameFillColor(41);
   gPad->SetGridx();
   gPad->SetGridy();

// Open a frame channel
   fc = new VFrameChannel("demoDB.root");
   
// Start time
   Double_t time = fc->GetStart();

// Histogram to constrain the limits
   hisfr = new TH1F("hisfr","Histogram of MYGO_ADC1 values",100,0.,3000.);
   hisfr->SetMarkerColor(4);
   hisfr->SetMarkerStyle(8);
   hisfr->SetMarkerSize(0.7);

// Get the first frame with absolute time
   fr = fc->GetFrame(time);
   Int_t nfram = 0;
   while ( (fr!=0) && (nfram<nframmax) ) {
      nfram++;
      printf("nfram = %dn",nfram);

//   Draws the vector (only in the signal region)
//   Do not need to extract a vector to do that,
//   the draw method will do it for you if you specify "adc.name"
      c1->cd(1);
      gVM->Draw(fr,"adc.MYGO_ADC1",0.13,0.07);
//   Get the corresponding VSPlot and set the color to blue
      VSPlot* vfp = gVM->GetLastPlot();
      vfp->SetLineColor(4);
      vfp->GetXaxis()->SetTimeDisplay(1); // axis labels displayed as time

//   Fill the histogram (accumulates it) and draw it
//   the + option in front of the name of the histogram
//   means that it's content is not erased before each fill
      c1_2->cd(1);
      gVM->DrawHist(fr,"adc.MYGO_ADC1",0.13,0.07,"+hisfr","e1");

//   Extracts the vector and alculates it's spectrum
      vect = VGetVect(fr,"adc.MYGO_ADC1");
      fft = FrvRFFTFor(0,vect);
//   Now plots it. Log scales are set by default (type of vector=spectrum)
      c1_2->cd(2);
      gVM->Draw(fft->amplitude);
//   Get the corresponding VSPlot and set the color to dark red
      VSPlot* vfp = gVM->GetLastPlot();
      vfp->SetLineColor(50);
      
//   Update the canvas
      c1->Update();

// Clean up the allocated variables
      FrvRFFTFree(fft);
      FrameFree(fr);

      fr = fc->GetNextFrame(); // Get the next frame
   }

// Fits the histogram and draws the fit result
   c1_2->cd(1);
   hisfr->Fit("gaus");
   hisfr->SetMarkerColor(4);
   hisfr->SetMarkerStyle(8);
   hisfr->SetMarkerSize(0.7);
   hisfr->Draw("e1");
   
   gBenchmark->Show("scroll2spectrum");
}
  

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