ROOT 6.18/05 Reference Guide |
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.
\[ Gini(Sample M) = 1 - (\frac{c(1)}{N})^2 - (\frac{c(2)}{N})^2 .... - (\frac{c(k)}{N})^2 \]
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 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... | |
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>
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inline |
Definition at line 64 of file GiniIndexWithLaplace.h.
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inline |
Definition at line 67 of file GiniIndexWithLaplace.h.
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inlinevirtual |
Definition at line 70 of file GiniIndexWithLaplace.h.
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virtual |
Implements TMVA::SeparationBase.
Definition at line 82 of file GiniIndexWithLaplace.cxx.