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// Input: 2 histogram
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// Output: one histogram which is the efficiency:
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// h1 : TOTAL NUMBER OF EVENTS
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// h2 : NUMBER OF EVENTS THAT PASS
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#include "TList.h"
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#include "TIterator.h"
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#include "TObject.h"
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#include "TString.h"
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#include "TDirectory.h"
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#include <iostream>
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#include "eff.h"
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// Method by pointer
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TH1F* eff(TH1F* h1, TH1F* h2, const char* name) {
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// first, verify that all histograms have same binning
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// nx is the number of visible bins
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// nxtot = nx+2 includes underflow and overflow
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Int_t nx = h1->GetNbinsX();
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if (h2->GetNbinsX() != nx) {
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std::cout << "Histograms must have same number of bins" << std::endl;
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return 0;
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}
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// get the new histogram
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TH1F* temp = (TH1F*) h1->Clone(name);
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temp->SetTitle(name);
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temp->Reset();
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temp->Sumw2();
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// Do the calculation
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temp->Divide(h2, h1, 1., 1., "B");
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// Done
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return temp;
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}
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// Method by name
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TH1F* eff(const char* name1, const char* name2, const char* name) {
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// Get a list of object and their iterator
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TList* list = gDirectory->GetList() ;
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TIterator* iter = list->MakeIterator();
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// Loop over objects, set the pointers
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TObject* obj;
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TH1F* h1 = 0;
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TH1F* h2 = 0;
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TString str1 = Form("%s", name1);
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TString str2 = Form("%s", name2);
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while (obj = iter->Next()) {
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TString objName = obj->GetName();
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if (objName == str1) h1 = (TH1F*) obj;
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if (objName == str2) h2 = (TH1F*) obj;
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}
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// quit if not found
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if (h1 == 0) {
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std::cout << "Histogram " << name1 << " not found" << std::endl;
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return 0;
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}
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if (h2 == 0) {
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std::cout << "Histogram " << name2 << " not found" << std::endl;
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return 0;
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}
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// Call the method by pointer
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TH1F* temp = eff(h1, h2, name);
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return temp;
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}
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