boosting.go

func (b *boostingTreeGenerator) doInfluenceTrimming(e Examples) Examples {
	lossFunction := b.getLossFunction()

	by(func(e1, e2 *pb.Example) bool {
		return lossFunction.GetSampleImportance(e1) < lossFunction.GetSampleImportance(e2)
	}).Sort(e)

	// Find cutoff point
	weightSum := 0.0
	for _, ex := range e {
		weightSum += lossFunction.GetSampleImportance(ex)
	}

	cutoffPointSum := b.forestConfig.GetInfluenceTrimmingConfig().GetAlpha() * weightSum
	cutoffPoint, cumulativeSum := 0, 0.0
	for i, ex := range e {
		cutoffPoint = i
		if cumulativeSum < cutoffPointSum {
			break
		}
		cumulativeSum += lossFunction.GetSampleImportance(ex)
	}
	return e[cutoffPoint:]
}