func (l *LightLOF) add(v nearest.FeatureVector) ID {
var nnID nearest.ID
if len(l.kdists) <= l.maxSize {
l.kdists = append(l.kdists, 0)
l.lrds = append(l.lrds, 0)
nnID = nearest.ID(len(l.kdists))
} else {
// unlearn
nnID = nearest.ID(l.rg.Intn(l.maxSize)) + 1
l.kdists[nnID-1] = 0
l.lrds[nnID-1] = 0
}
l.nn.SetRow(nnID, v)
neighbors := l.nn.NeighborRowFromID(nnID, l.rnnNum)
nestedNeighbors := map[ID][]nearest.IDist{}
for i := range neighbors {
nnID := neighbors[i].ID
id := ID(nnID)
nnResult := l.nn.NeighborRowFromID(nnID, l.nnNum)
nestedNeighbors[id] = nnResult
l.kdists[id-1] = nnResult[len(nnResult)-1].Dist
}
for i := range neighbors {
nnID := neighbors[i].ID
id := ID(nnID)
nn := nestedNeighbors[id]
var lrd float32 = 1
if len(nn) > 0 {
length := minInt(len(nn), l.nnNum)
var sumReachability float32
for i := 0; i < length; i++ {
sumReachability += maxFloat32(nn[i].Dist, l.kdists[nn[i].ID-1])
}
if sumReachability == 0 {
lrd = inf32
} else {
lrd = float32(length) / sumReachability
}
}
l.lrds[id-1] = lrd
}
return ID(nnID)
}
func (l *LightLOF) collectLRDsByID(id ID) (float32, []float32) {
nnID := nearest.ID(id)
neighbors := l.nn.NeighborRowFromID(nearest.ID(id), l.nnNum+1)
if len(neighbors) == 0 {
return inf32, nil
}
for i := range neighbors {
if neighbors[i].ID == nnID {
copy(neighbors[1:i+1], neighbors[0:])
neighbors = neighbors[1:]
break
}
}
if len(neighbors) > l.nnNum {
neighbors = neighbors[:l.nnNum]
}
if len(neighbors) == 0 {
return inf32, nil
}
return l.collectLRDsImpl(neighbors)
}