Hi Casper, great to see your interest with HTM! Some answers below...
On Wed, Oct 14, 2015 at 2:56 PM, Cas <casper.roo...@gmail.com> wrote: > Hi, > > I'm working on a proof of concept for enabling anomaly detection in a > monitored environment. I've decided to incorporate NuPIC in the PoC. I'm > trying to gain insight in the pro's and con's of using the framework. I'm > particularly interested in the workings of the anomaly score and anomaly > likelihood. > > I have some questions: > > What part of the framework outputs anomaly scores and anomaly likelihood? > Anomaly class, in src/nupic/algorithms/anomaly.py and anomali_likelihood.py > What factors determine the minimum sample size for anomaly likelihood? > There is some burn-in period for likelihood to be able to evaluate the estimates, but not limited only for anomaly, all parts of HTM need some time to settle - for the SpatialPooler to be able to create stable and "high quality" SDR representations, same for TP; in my experience on complex data this is about 1000-3000 samples. Is it possible to judge if an input stream is too noisy for useful anomaly > detection? > IMHO you should be almost always fine. (consider you are talking about point-anomalies?) Unless they happen significantly ofthen HTM will detect them. If they do happen significantly ofthen, it is not an anomaly anymore. The likelihood model can eg. train to "become used to" a white noise, and then a const line would be considered anomalous, for a period of time. > Are there insights on the accuracy and reliability of anomaly detection > after prolonged use? I imagine HTM regions could become too saturated with > pattern variations to provide consistent anomaly detection over time. > In my experience your accuracy would improve, see the example above. What will get worse is the speed, as HTM implementation slows down as more segments etc are created. Btw, can you share some insight in what your use-case is? Cheers, Mark > > I hope you can help me out. > > With regards, > > Casper Rooker > casper.roo...@gmail.com > -- Marek Otahal :o)
