Hi Tom, what you are describing is "correct" behavior. The way the scalar encoder works is that similar numbers have similar representations. So if your usecase normal values are in range 25..25, say, and low 1..3, then 0 is not an anomaly to the encoder.
You have two choices, alter the data (I think the fastes), just apply some transformation to make bigger distance between 0 and the low values; other option is replace the 0 with something else...can the scalar encoder accept N/A value (i think it can, a None), or you'll need to modify your encoder. Regards, Mark On Wed, Dec 11, 2013 at 7:53 AM, Tom Tan <[email protected]> wrote: > Hi, > > I am very intrigued by Nupic CLA and its potentials. I was trying to use > CLA algorithm to perform anomaly detection. My data set is similar to that > of the hotgym example - the usage is high during the day/business hours and > low, but never zero, during night/non-business hours (sorry I can’t share > my data set). The zero usage means outage and should be considered as an > anomaly regardless when it happens. The problem is CLA failed to raise > anomaly score when outage/zero usage happening during the non-business > hours. > > I managed to reproduce the problem using the the hot gym anomaly example. > > I made following change to "extra/hotgym/rec-center-hourly.csv" > > 4373,4374c4373,4374 > < 12/31/10 1:00,0 > < 12/31/10 2:00,0 > --- > > 12/31/10 1:00,4.9 > > 12/31/10 2:00,5 > > that means zero energy usage during the 1 & 2 AM, which should be > abnormal. And corresponding CLA score are 0 (shown below) > > INFO:__main__:Anomaly detected at [2010-12-31 01:00:00]. Anomaly score: > 0.000000. > INFO:__main__:Anomaly detected at [2010-12-31 02:00:00]. Anomaly score: > 0.000000. > > When I used 24 “traditional” statistical models, each for an hour of the > day, I was able to detect zero usage and report as an anomaly. CLA doesn’t > appear to be superior in this case. > > Can CLA model be tuned to account for scenarios like this? > > Regards, > Tom > > > _______________________________________________ > nupic mailing list > [email protected] > http://lists.numenta.org/mailman/listinfo/nupic_lists.numenta.org > > -- Marek Otahal :o)
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