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#include "TrkUpgradeAnalysis/VHbb/interface/tools.h"
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#include <stdexcept>
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#include <iostream>
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#include <TFile.h>
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#include <TH1F.h>
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trkupgradeanalysis::tools::TFile_auto_ptr::TFile_auto_ptr( const std::string& filename )
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{
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this->reset( TFile::Open( filename.c_str() ) );
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}
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trkupgradeanalysis::tools::TFile_auto_ptr::~TFile_auto_ptr()
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{
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// If the pointer is not null, close the file. Let the auto_ptr destructor delete it.
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if( this->get() ) this->get()->Close();
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}
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bool trkupgradeanalysis::tools::TFile_auto_ptr::operator==( const TFile* pOtherFile )
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{
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return this->get()==pOtherFile;
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}
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float trkupgradeanalysis::tools::linearInterpolate( std::pair<float,float> point1, std::pair<float,float> point2, float requiredY )
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{
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// Using the equation for a straight line of y=mx+c, work out m and c so
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// that the line passes through point1 and point2
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float m=(point1.second-point2.second)/(point1.first-point2.first);
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float c=point2.second-m*point2.first;
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// Then I can return x=(y-c)/m
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return (requiredY-c)/m;
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}
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float trkupgradeanalysis::tools::findDiscriminator( const TH1F* pEventsVersusDiscriminatorHistogram, const float requiredEfficiency, const bool verbose )
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{
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if( pEventsVersusDiscriminatorHistogram==NULL ) throw std::runtime_error("findDiscriminator was called with a NULL histogram pointer");
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TAxis* pHistogramXAxis=pEventsVersusDiscriminatorHistogram->GetXaxis();
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float accumulatedEvents=0; // The number of events that would pass the current cut (i.e. number of events in this bin and all higher ones)
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float previousEfficiency=1; // The efficiency on the last run through the loop. Set high for logic to work
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// Loop backwards over each of the bins in the histogram
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for( int bin=pHistogramXAxis->GetNbins(); bin>=1; --bin )
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{
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accumulatedEvents+=pEventsVersusDiscriminatorHistogram->GetBinContent(bin);
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float currentEfficiency=accumulatedEvents/pEventsVersusDiscriminatorHistogram->GetEntries();
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// See if this loop has gone a bin too far. If so interpolate between this and the previous loop.
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if( currentEfficiency>requiredEfficiency )
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{
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// The working point is somewhere between the previous bin and this bin.
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// Do a linear interpolation between the bins.
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std::pair<float,float> point1( pHistogramXAxis->GetBinLowEdge(bin), currentEfficiency );
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std::pair<float,float> point2( pHistogramXAxis->GetBinLowEdge(bin+1), previousEfficiency );
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float operatingPoint=trkupgradeanalysis::tools::linearInterpolate( point1, point2, requiredEfficiency );
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if( verbose )
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{
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std::cout << "[findDiscriminator verbose] The operating point of " << requiredEfficiency << " efficiency for \"" << pEventsVersusDiscriminatorHistogram->GetName() << "\" is between:" << "\n"
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<< "[findDiscriminator verbose] \t" << pHistogramXAxis->GetBinLowEdge(bin) << " -> " << currentEfficiency << " (bin " << bin << ") and " << "\n"
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<< "[findDiscriminator verbose] \t" << pHistogramXAxis->GetBinLowEdge(bin+1) << " -> " << previousEfficiency << " (bin " << bin+1 << ")." << "\n"
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<< "[findDiscriminator verbose] Linear interpolation gives:" << "\n"
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<< "[findDiscriminator verbose] \t" << operatingPoint << std::endl;
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}
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return operatingPoint;
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}
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previousEfficiency=currentEfficiency; // Set this ready for the next loop around
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} // end of backwards loop over histogram bins
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// If flow has got this far, something has gone wrong
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throw std::runtime_error("findDiscriminator was unable to find an operating point");
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} // end of function findDiscriminator
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float trkupgradeanalysis::tools::findEfficiency( const TH1F* pEventsVersusDiscriminatorHistogram, const float requiredDiscriminator, const bool verbose )
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{
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if( pEventsVersusDiscriminatorHistogram==NULL ) throw std::runtime_error("findEfficiency was called with a NULL histogram pointer");
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TAxis* pHistogramXAxis=pEventsVersusDiscriminatorHistogram->GetXaxis();
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float accumulatedEvents=0; // The number of events that would pass the current cut (i.e. number of events in this bin and all higher ones)
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float previousEfficiency=1; // The efficiency on the last run through the loop. Set high for logic to work
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// Loop backwards over each of the bins in the histogram
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for( int bin=pHistogramXAxis->GetNbins(); bin>=1; --bin )
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{
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accumulatedEvents+=pEventsVersusDiscriminatorHistogram->GetBinContent(bin);
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float currentEfficiency=accumulatedEvents/pEventsVersusDiscriminatorHistogram->GetEntries();
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// See if this loop step has gone too far, if so then interpolate between this and the previous step.
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if( pHistogramXAxis->GetBinLowEdge(bin)<requiredDiscriminator )
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{
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// The efficiency is somewhere between the previous bin and this bin.
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// Do a linear interpolation between the bins. This is similar to findDiscriminator but
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// I've switched around the x and y coordinates.
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std::pair<float,float> point1( currentEfficiency, pHistogramXAxis->GetBinLowEdge(bin) );
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std::pair<float,float> point2( previousEfficiency, pHistogramXAxis->GetBinLowEdge(bin+1) );
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float efficiency=trkupgradeanalysis::tools::linearInterpolate( point1, point2, requiredDiscriminator );
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if( verbose )
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{
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std::cout << "[findEfficiency verbose] The discriminator of " << requiredDiscriminator << " for \"" << pEventsVersusDiscriminatorHistogram->GetName() << "\" is between:" << "\n"
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<< "[findEfficiency verbose] \t" << pHistogramXAxis->GetBinLowEdge(bin) << " -> " << currentEfficiency << " (bin " << bin << ") and " << "\n"
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<< "[findEfficiency verbose] \t" << pHistogramXAxis->GetBinLowEdge(bin+1) << " -> " << previousEfficiency << " (bin " << bin+1 << ")." << "\n"
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<< "[findEfficiency verbose] Linear interpolation gives an efficiency of:" << "\n"
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<< "[findEfficiency verbose] \t" << efficiency << std::endl;
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}
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return efficiency;
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}
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previousEfficiency=currentEfficiency; // Set this ready for the next loop around
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} // end of backwards loop over histogram bins
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// If flow has got this far, something has gone wrong
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throw std::runtime_error("findEfficiency was unable to find an operating point");
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} // end of function findEfficiency
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