So, this just goes to show you the outdated things we learn in school. :))
On Sat, Mar 30, 2013 at 4:15 PM, Ted Dunning <ted.dunn...@gmail.com> wrote: > SOM doesn't have to be constrained to two dimensions. > > That said, there are bunches of non-linear embedding methods that are more > current than SOM's. SOM's were part of the neural plausibility movement of > the late 80's which more recently can be seen as an approach toward modern > formulations of stochastic gradient descent. > > For one example, Hector Yee was just recommending that Affinity Based > Emedding [1] would be a useful think to look at. I would find it hard to > say what would be a useful project in that regard. > > More central to Mahout's general areas of excellence would be an > implementation of Latent factor Log Linear models [2]. These would provide > a very interesting complement to the alternating least squares methods that > have been developed lately in Mahout. > > Either of these would strike me as more useful in the Mahout context than > SOM's. > > [1] http://arxiv.org/abs/1301.4171 > > [2] http://arxiv.org/abs/1006.2156 > > > On Sat, Mar 30, 2013 at 12:21 PM, Sean Owen <sro...@gmail.com> wrote: > > > Are SOMs actually good at dimension reduction? I had understood it to > > just be a visualization technique. You end up with a mapping with the > > property that things that are near are similar, but no guarantee that > > things that are similar are near. > > > > On Sat, Mar 30, 2013 at 12:06 PM, Dan Filimon > > <dangeorge.fili...@gmail.com> wrote: > > > Hi, > > > > > > I have a larger assignment to work on for my Machine Learning course > this > > > semester and I can pick one of 4 problems to solve. > > > > > > One of them, is implementing self organizing maps and using them to > > cluster > > > the Localization Data for Person Activity Data Set [1] and evaluate > the > > > clustering with the Dunn Index and F-measure. > > > > > > I vaguely recall talking to Ted about self organizing maps as a way of > > > achieving dimensionality reduction, so that's where it could be useful. > > > > > > I need to pick a problem anyway and was wondering if there's any sort > of > > > interest in this one. > > > If yes, I could work on an implementation for Mahout (likely non > > MapReduce, > > > at least for the purposes of this assignment). > > > > > > Thoughts? > > > > > > [1] > > > > > > http://archive.ics.uci.edu/ml/datasets/Localization+Data+for+Person+Activity > > >
