| double Impala::Core::Feature::Gain | ( | const AnnotatedFeatureTable * | data, | |
| int | nrClasses, | |||
| bool * | left, | |||
| bool * | right | |||
| ) |
according to Jasper: The Gain is defined as in [Shotton08], taken again from Lepetit, CVPR 2005
Definition at line 68 of file MakeRandomTree.h.
References Impala::Util::Count(), Impala::Core::Histogram::Entropy(), MakeHistogram(), and Impala::Core::Table::Table::Size().
Referenced by Impala::Core::Feature::TestMakeRandomTree::testFindSplitWithSeed(), Impala::Core::Feature::TestMakeRandomTree::testGain(), and TryRandomSplit().
00069 { 00070 int size = data->Size(); 00071 double nrL = Util::Count(left, size); 00072 double nrR = Util::Count(right, size); 00073 double total = nrL+nrR; 00074 if(total==0) 00075 return 0; 00076 Histogram::Histogram1dTem<int>* histL = MakeHistogram(data, nrClasses, left); 00077 Histogram::Histogram1dTem<int>* histR = MakeHistogram(data, nrClasses, right); 00078 double gain = - (nrL / total) * Entropy(histL) - (nrR / total) * Entropy(histR); 00079 delete histL; 00080 delete histR; 00081 return gain; 00082 }
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