Overplots with 1D histogram

ROOT
1

Hello All,
I am trying to plot 3 text files as 1-D histograms. I can open one text file and make a histogram but cannot figure out how to make an over plot. Can any one give me some hints about hot I can over plot with suitable legends in the plot.
Here is what I have for reading just one file. I have 3 files 18.txt, 20.txt and 22.txt and I want all of them on the same plot for comparison purposes.

[code]{
gROOT->Reset();

TH1F *AxialSensitivityDet = new TH1F(“AxialSensitivityDet”,“Axial sensitivity”,50,-100.,+100.);

Int_t runID;
Float_t z;

FILE *out;
out=fopen(“18.txt”,“r”);

while(!feof(out)){
fscanf(out,"%f",&z);
//printf("%f\n",z);
AxialSensitivityDet->Fill(z);
}

fclose(out);
AxialSensitivityDet->Draw();
}[/code]

UPDATE: I messed about and got it working:

{
   gROOT->Reset();

   TCanvas *c1 = new TCanvas("c1","Axial Sensitivity",200,10,600,400);
   //TCanvas *c2 = new TCanvas("c2","Two Graphs",200,10,600,400);
   
   TH1F *AS18 = new TH1F("AS18","Axial sensitivity",50,-100.,+100.);
   TH1F *AS20 = new TH1F("AS20","Axial sensitivity",50,-100.,+100.);
   TH1F *AS22 = new TH1F("AS22","Axial sensitivity",50,-100.,+100.);
   
   Float_t         z;
   
   FILE *out;

   out=fopen("18.txt","r"); while(!feof(out)) { fscanf(out,"%f",&z); AS18->Fill(z); } fclose(out);
   out=fopen("20.txt","r"); while(!feof(out)) { fscanf(out,"%f",&z); AS20->Fill(z); } fclose(out);
   out=fopen("22.txt","r"); while(!feof(out)) { fscanf(out,"%f",&z); AS22->Fill(z); } fclose(out);
 
   AS22->GetXaxis()->SetTitle("Axial position (mm)");
   AS22->GetYaxis()->SetTitle("Counts");
   
   AS22->SetFillColor(1);AS22->SetMarkerStyle(23); AS22->SetMarkerColor(1);AS22->Draw();
   AS20->SetFillColor(2);AS20->SetMarkerStyle(22); AS20->SetMarkerColor(2);AS20->Draw("same");
   AS18->SetFillColor(3);AS18->SetMarkerStyle(21); AS18->SetMarkerColor(3);AS18->Draw("same");

   TLegend *legend = new TLegend(.75,.80,.95,.95);
   legend->AddEntry(AS18,"18 mm");
   legend->AddEntry(AS20,"20 mm");
   legend->AddEntry(AS22,"22 mm");
   legend->Draw("same");
}

How do I remove the A22 legend (the one with the entries, Mean, RMS etc).

Thanks.

2

Add the statement disabling the stats box, ie

AS22->SetStats(0);
and replace

legend->Draw("same"); by

legend->Draw();
Rene

3

Thanks.