Problem with TH1::Draw

Damon Spayde (dspayde@physics.umd.edu)
Tue, 13 Jul 1999 08:28:03 -0400 (EDT)

I have written a script that reads in an ASCII file and generates three
one-dimensional histograms of its contents. I would really like to look
at these histograms in bar graph form; i.e. with a bar for each bin.
However, when I specify the option "B" in TH1::Draw() the histogram gets
drawn with little tiny points and error bars for each bin. Any help in
understanding why this is happening would be greatly appreciated. My ROOT
version is 2.21/08, run on a DEC Alpha with Digital Unix 4.0d. ROOT was
compiled using gcc version 2.8.1. Below I have included a copy of the
script.

Thanks,
Damon Spayde

--------------------------------
Damon Spayde
Department of Physics
University of Maryland
PO Box 175
College Park, MD 20742
Phone: (301) 405-6113
Fax: (301) 405-8558
e-mail: dspayde@physics.umd.edu
--------------------------------

//////////////////////////////////////////////////////////////////
// //
// dotout_hist -- Create a histogram of a *.out file's contents //
// //
// Author: Damon Spayde //
// //
// Usage: //
// //
// Caveats: //
// 1) Assumes that badruns file and ADC files are sorted. //
// //
//////////////////////////////////////////////////////////////////

#include <fstream.h>

struct Badrun
{
Int_t low;
Int_t high;
};

struct Adc
{
Int_t runnumber;
Int_t helicity;
Int_t events;
Double_t yield;
Double_t yield_error;
Double_t yield_width;
Int_t pulsepairs;
Double_t asym;
Double_t asym_error;
Double_t asym_width;
};


const Int_t IN = -1;
const Int_t OUT = 1;
const Double_t PPM = 1.0e6;

Int_t dotout_hist(Char_t *adc_file,Int_t first_run,Int_t last_run, Char_t *badruns_file = "badruns.dat")
{

// Initialization
Adc adc;
Badrun badrun;
ifstream BADRUNSfile(badruns_file); // Open badruns.dat for
// reading
if(BADRUNSfile.bad()) {
cerr << "Error: Could not open badruns_file.\n";
exit(7);
}

Char_t adc_filename[40];
sprintf(adc_filename,"%s.out",adc_file);
ifstream ADCfile(adc_filename); // Open appropriate .out file for
// reading
if(ADCfile.bad()) {
cerr << "Error: Could not open adc_filename.\n";
exit(8);
}

Char_t hname[20];
Char_t htitle[80];
sprintf(hname,"h_%s",adc_file);
sprintf(htitle,"Weighted Asymmetry Histogram in %s over Runs
%d to %d, Both Wave Plate States",adc_file,first_run,last_run);
TH1F *adc_hist = new TH1F(hname,htitle,200,-100,100); //Create a new
//histogram

sprintf(hname,"h_in_%s",adc_file);
sprintf(htitle,"Weighted Asymmetry Histogram in %s over Runs %d to
%d, Wave Plate In",adc_file,first_run,last_run);
TH1F *adc_in_hist = new TH1F(hname,htitle,200,-100,100); //Create a new
//histogram

sprintf(hname,"h_out_%s",adc_file);
sprintf(htitle,"Weighted Asymmetry Histogram in %s over Runs %d to
%d, Wave Plate Out",adc_file,first_run,last_run);
TH1F *adc_out_hist = new TH1F(hname,htitle,200,-100,100); //Create a new
//histogram

adc_hist->Sumw2(); // Record sum of weights for each bin of
// histogram
adc_in_hist->Sumw2(); // Record sum of weights for each bin of
// histogram
adc_out_hist->Sumw2(); // Record sum of weights for each bin of
// histogram

// Loop over the adc file until line corresponding to first run or
// greater is loaded into the first struct
do {
ADCfile >> adc.runnumber >> adc.helicity;
ADCfile >> adc.events >> adc.yield >> adc.yield_error;
ADCfile >> adc.pulsepairs >> adc.asym >> adc.asym_error;
// cout << adc.runnumber << ": " << adc.asym << "\n";
} while (adc.runnumber < (first_run - 1));

do {
BADRUNSfile >> badrun.low >> badrun.high;
} while (badrun.high < first_run);

// Loop over all file lines
Int_t i = ;
Int_t j = ;

while(adc.runnumber >= (first_run - 1) && adc.runnumber <= last_run) {

ADCfile >> adc.runnumber >> adc.helicity;
ADCfile >> adc.events >> adc.yield >> adc.yield_error;
ADCfile >> adc.pulsepairs >> adc.asym >> adc.asym_error;
adc.asym *= PPM;
adc.asym_error *= PPM;
adc.yield_width = adc.yield * sqrt(adc.events);
adc.asym_width = adc.asym * sqrt(adc.pulsepairs);

cout << adc.runnumber << ": " << adc.asym << "\n";

do {
if (badrun.high < adc.runnumber) { // Is it necessary to read
// another line of
// badruns.dat?
BADRUNSfile >> badrun.low >> badrun.high;
}

if (adc.runnumber < badrun.low) {
// Put hist fill here
adc_hist->Fill((Axis_t) adc.helicity*adc.asym,(Stat_t)
1.0/(adc.asym_error * adc.asym_error));
switch (adc.helicity) {
case IN:
adc_in_hist->Fill((Axis_t) adc.asym,(Stat_t) 1.0/(adc.asym_error * adc.asym_error));
break;
case OUT:
adc_out_hist->Fill((Axis_t) adc.asym,(Stat_t) 1.0/(adc.asym_error * adc.asym_error));
break;
default:
printf("Error: helicity not equal to +/-1 for run
%d.\n",adc.runnumber);
break;
}
}

} while (badrun.high < adc.runnumber);

}

ADCfile.close();
BADRUNSfile.close();

Char_t ctitle[40];
sprintf(ctitle,"%s Histograms",adc_file);
TCanvas *c2 = new TCanvas("c2",ctitle,600,777);
c2->SetBorderMode(0);
c2->SetFillColor(0);
gStyle->SetPadBorderMode(0);
gStyle->SetFillColor(0);
c2->Divide(1,3);
c2->cd(1);
adc_in_hist->Draw("B");
adc_in_hist->Print();
gPad->SetLogy(1);
gPad->Modified();
c2->cd(2);
adc_out_hist->Draw("B");
adc_out_hist->Print();
gPad->SetLogy(1);
gPad->Modified();
c2->cd(3);
adc_hist->Draw("B");
adc_hist->Print();
gPad->SetLogy(1);
gPad->Modified();
c2->Modified();


}