Implementation of the GiniIndex 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.

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

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:

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

Definition at line 63 of file GiniIndex.h.

Public Member Functions
	GiniIndex ()

	GiniIndex (const GiniIndex &g)

virtual	~GiniIndex ()

virtual Double_t	GetSeparationIndex (const Double_t s, const Double_t b)
	what we use here is 2*Gini. More...

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

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

virtual	~SeparationBase ()

const TString &	GetName ()

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...

Additional Inherited Members
Protected Attributes inherited from TMVA::SeparationBase
TString	fName

Double_t	fPrecisionCut

Inheritance diagram for TMVA::GiniIndex:

Constructor & Destructor Documentation

◆ GiniIndex() [1/2]

TMVA::GiniIndex::GiniIndex ( )

inline

Definition at line 68 of file GiniIndex.h.

TMVA::GiniIndex::GiniIndex ( const GiniIndex & g )

inline

Definition at line 71 of file GiniIndex.h.

virtual TMVA::GiniIndex::~GiniIndex ( )

inlinevirtual

Definition at line 74 of file GiniIndex.h.

Double_t TMVA::GiniIndex::GetSeparationIndex	(	const Double_t	s,
		const Double_t	b
	)

virtual

what we use here is 2*Gini.

. as for the later use the factor 2 is irrelevant and hence I'd like to save this calculation

Definition at line 76 of file GiniIndex.cxx.

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