func NewDetector(normalCount int, consensus, minSupport, errorTolerance float64, fingerprinters []Fingerprinter) *Detector {
//TODO perform sanity check on minsupport and normalcount to make sure
// its still possible to mark something as anomalous
counters := make([]fingerprinterCounter, len(fingerprinters))
for i, fingerprinter := range fingerprinters {
counters[i] = fingerprinterCounter{
fingerprinter,
counter.NewLossyCounter(minSupport, errorTolerance),
}
}
return &Detector{
normalCount: normalCount,
consensus: consensus,
minSupport: minSupport,
errorTolerance: errorTolerance,
counters: counters,
}
}
// Create a new Lossy couting based detector
// The consensus is a percentage of the fingerprinters that must agree in order to flag a window as anomalous.
// If the consensus is -1 then the average support from each fingerprinter is compared to minSupport instead of using a consensus.
// The minSupport defines a minimum frequency as a percentage for a window to be considered normal.
// The errorTolerance defines a frequency as a precentage for the smallest frequency that will be retained in memory.
// The errorTolerance must be less than the minSupport.
func NewDetector(consensus, minSupport, errorTolerance float64, fingerprinters []Fingerprinter) (*Detector, error) {
if (consensus != -1 && consensus < 0) || consensus > 1 {
return nil, errors.New("consensus must be in the range [0,1) or equal to -1")
}
if minSupport <= errorTolerance {
return nil, errors.New("minSupport must be greater than errorTolerance")
}
counters := make([]fingerprinterCounter, len(fingerprinters))
for i, fingerprinter := range fingerprinters {
counters[i] = fingerprinterCounter{
fingerprinter,
counter.NewLossyCounter(errorTolerance),
}
}
return &Detector{
consensus: consensus,
minSupport: minSupport,
errorTolerance: errorTolerance,
counters: counters,
}, nil
}