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From Dan Filimon <dangeorge.fili...@gmail.com>
Subject Re: Interest in Self Organizing Maps?
Date Sat, 30 Mar 2013 15:19:24 GMT
So, this just goes to show you the outdated things we learn in school.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.dunning@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 <srowen@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.filimon@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
> >
>

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