I would go over the properties of the SP and create tests accordingly. The output, for instance, should be tolerant to spatial noise. So show an instance a set of very different spatial patterns over and over a number of times. Then show one of the patterns with a single bit flipped and make sure the output is very close (possibly identical if columns are saturated) to the same.
There are a bunch of similar things you could check. Ian had a hackathon demo showing the connected bits for each column. He was able to validate different aspects of the SP visually by using different numbers of columns and % overlap. You could do something similar to make sure you see the right behavior but I don't know if you could make an automated test out of it. http://numenta.org/blog/2013/11/06/2013-fall-hackathon-outcome.html#sp_viewer On Feb 4, 2014 11:23 AM, "Jeff Hawkins" <[email protected]> wrote: > Kevin, > > Adding on to what Fergal said.... > > > > Here is what we did. We started with a fixed number of columns and no > topology. In this situation we picked the n% most innervated columns as > the output of the SP. Thus we were *guaranteed* to get the correct > sparsity of active columns. With this setup we did a lot of other tests to > verify that the SP was forming good representations. > > > > The tricky part is if you want to do this with topology and local learning > rules. Is that your concern? > > > > With topology we didn't try to guarantee the entire layer of cells will > have exactly n% active columns. Exact numbers are not essential. We tried > several different local learning rules, all of them produced about the > right level of sparsity. We than ran the other tests to make sure that > local learning rules didn't cause the SP to form poor representations. You > won't get exactly the same results with topology and without topology but > my recollection was we were able to come up with a set of local inhibition > rules that produced good results. > > Jeff > > > > *From:* nupic [mailto:[email protected]] *On Behalf Of *Fergal > Byrne > *Sent:* Tuesday, February 04, 2014 10:43 AM > *To:* NuPIC general mailing list. > *Subject:* Re: [nupic-discuss] Tests for spatial pooling > > > > Hi Kevin, > > > > If you're using no topology (and no local inhibition) then the fraction of > active columns (2% in NuPIC) is the only important factor. With topology, > you should choose winners relative to their neighbours. In either case, the > first test is to count the fraction of active columns. In the second case, > measure the average distance between active columns. > > > > Regards, > > > > Fergal Byrne > > > > On Tue, Feb 4, 2014 at 6:05 PM, Kevin Martin <[email protected]> > wrote: > > Hi, > > I'm writing my own version of the CLA. I have not reached anywhere > significant and I have been playing with a very small number of columns > until now. I am starting by implementing a spatial pooler and spatial > pooling requires a large number of columns. So far it has been easy to > manually check if the synapses are distributed throughout the input, if the > winning columns are really sparse etc. But it is going to be impossible > when, say,I use 1000 columns. Have somebody used a test to check if the > spatial pooler outputs a sparse distribution? Any suggestions on how to > write a test? > > Thanks, > > Kevin Martin Jose > > > _______________________________________________ > nupic mailing list > [email protected] > http://lists.numenta.org/mailman/listinfo/nupic_lists.numenta.org > > > > > > -- > > > Fergal Byrne, Brenter IT > > > > http://inbits.com - Better Living through Thoughtful Technology > > > > e:[email protected] t:+353 83 4214179 > > Formerly of Adnet [email protected] http://www.adnet.ie > > _______________________________________________ > nupic mailing list > [email protected] > http://lists.numenta.org/mailman/listinfo/nupic_lists.numenta.org > >
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