ROOT   Reference Guide
TMVA::GiniIndexWithLaplace Class Reference

Implementation of the GiniIndex With Laplace correction as separation criterion.

Large Gini Indices (maximum 0.5) mean , that the sample is well mixed (same amount of signal and bkg) bkg.

Small Indices mean, well separated.

General definition:

$Gini(Sample M) = 1 - (\frac{c(1)}{N})^2 - (\frac{c(2)}{N})^2 .... - (\frac{c(k)}{N})^2$

Where:

$$M$$ is a sample of whatever $$N$$ elements (events) that belong to $$K$$ different classes.

$$c(k)$$ is the number of elements that belong to class $$k$$ for just Signal and Background classes this boils down to:

The Laplace's correction to the probability distribution would turn the $$\frac{c(1)}{N}$$ into $$\frac{(c(1)+1)}{(N+2)}$$ using this the simple Gini Index for two classes

$Gini(Sample) = \frac{2sb}{(s+b)^2}$

turns into

$GiniLaplace(Sample) = \frac{2(sb+s+b+1)}{(s+b+2)^2}$

Definition at line 59 of file GiniIndexWithLaplace.h.

Public Member Functions

GiniIndexWithLaplace ()

GiniIndexWithLaplace (const GiniIndexWithLaplace &g)

virtual ~GiniIndexWithLaplace ()

virtual Double_t GetSeparationIndex (const Double_t s, const Double_t b)

Public Member Functions inherited from TMVA::SeparationBase
SeparationBase ()
Constructor. More...

SeparationBase (const SeparationBase &s)
Copy constructor. More...

virtual ~SeparationBase ()

const TStringGetName ()

virtual Double_t GetSeparationGain (const Double_t nSelS, const Double_t nSelB, const Double_t nTotS, const Double_t nTotB)
Separation Gain: the measure of how the quality of separation of the sample increases by splitting the sample e.g. More...

virtual Double_t GetSeparationIndex (const Double_t s, const Double_t b)=0

Additional Inherited Members

Protected Attributes inherited from TMVA::SeparationBase
TString fName

Double_t fPrecisionCut

#include <TMVA/GiniIndexWithLaplace.h>

Inheritance diagram for TMVA::GiniIndexWithLaplace:
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◆ GiniIndexWithLaplace() [1/2]

 TMVA::GiniIndexWithLaplace::GiniIndexWithLaplace ( )
inline

Definition at line 64 of file GiniIndexWithLaplace.h.

◆ GiniIndexWithLaplace() [2/2]

 TMVA::GiniIndexWithLaplace::GiniIndexWithLaplace ( const GiniIndexWithLaplace & g )
inline

Definition at line 67 of file GiniIndexWithLaplace.h.

◆ ~GiniIndexWithLaplace()

 virtual TMVA::GiniIndexWithLaplace::~GiniIndexWithLaplace ( )
inlinevirtual

Definition at line 70 of file GiniIndexWithLaplace.h.

◆ GetSeparationIndex()

 Double_t TMVA::GiniIndexWithLaplace::GetSeparationIndex ( const Double_t s, const Double_t b )
virtual

Implements TMVA::SeparationBase.

Definition at line 82 of file GiniIndexWithLaplace.cxx.

Libraries for TMVA::GiniIndexWithLaplace:
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The documentation for this class was generated from the following files: