Hi all,
Thanks for the help. But I'm not sure if I understand what you mean by topology. As far as I understand, the spatial pooler has 2 functions : Return a set of columns that are 1)sparse and 2)distributed. Sparsity can be maintained by making sure that the pooler returns only n% of columns and this criterion can be made into a test. And distribution can be tested by computing the average distance between winning columns. What is topology? Is it another way of referring to a distributed set of columns? I might need some help with local learning too. I'm afraid I have never heard the term before (its in the white paper? A quick search on the pdf did not see any hits for "local learning") Thanks, Kevin Martin On Wed, Feb 5, 2014 at 7:37 AM, Scott Purdy <[email protected]> wrote: > 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 >> >> > _______________________________________________ > nupic mailing list > [email protected] > http://lists.numenta.org/mailman/listinfo/nupic_lists.numenta.org > >
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