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From Jonathan Seale <jonathanpse...@gmail.com>
Subject Re: Row Similarity
Date Thu, 14 May 2015 18:18:16 GMT
Thanks, guys. Can you recommend any resources that show an example of these
steps? A google search returns very little information. Now I know what to
do, but I can't find anything that tells me how to do it.


On Wed, May 13, 2015 at 11:56 PM, Suneel Marthi <smarthi@apache.org> wrote:

> Hi Jonathan,
>
> Here's what u gotta do to run RowSimilarity on ur CSV formatted data.  You
> would have to use the MapReduce version since the Spark version only
> supports LLR.
>
> 1. Convert CSV to Vectors - use CSVIterator and store the vectors as
> SequenceFiles
> 2.  Run RowIDJob on the SequenceFile output of (1). This should generate a
> Matrix of <IntWritable, VectorWriteable> and a docIndex of <IntWritable,
> Text>
> 3.  Run RowSimilarityjob on the matrix output from (2) specifiying
> CosineDistance and a cutoff threshold. This should generate a matrix of
> Rows -> Most similar rows with distances.
>
>
>
>
> On Wed, May 13, 2015 at 11:42 PM, Jonathan Seale <jonathanpseale@gmail.com
> >
> wrote:
>
> > Thanks, Charlie,
> >
> > The data has been through lots of processing, but in an attempt to make
> it
> > more Mahout-friendly, I've converted it into a single csv table with
> > columns: star_id, wavelength, intensity. My motivation was to make it
> like
> > a user_id, item_id, rating table you might see in other Mahout uses.
> >
> > As opposed to using my local machine, I've setup an instance on Amazon
> with
> > hopes of turning this into a remote service. So the install is whatever
> > comes with Amazon's default Mahout installation.
> >
> > Jonathan
> >
> >
> >
> > On Wed, May 13, 2015 at 11:29 PM, Charlie Hack <charles.t.hack@gmail.com
> >
> > wrote:
> >
> > > Hi Jonathan, how do you have the data stored? More info about your
> setup
> > > the better.
> > >
> > >
> > > Charlie
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > —
> > > Sent from Mailbox
> > >
> > >
> > >
> > >
> > > On Wednesday, May 13, 2015 at 23:16, Jonathan Seale <
> > > jonathanpseale@gmail.com>, wrote:
> > > Scientists,
> > >
> > >
> > > I have an astrophysical application for Mahout that I need help with.
> > >
> > >
> > > I have 1-dimensional stellar spectra for many, many stars. Each
> spectrum
> > >
> > > consists of a series of intensity values, one per wavelength of light.
> I
> > >
> > > need to be able to find the cosine similarity between ALL pairs of
> stars.
> > >
> > > Seems to me this is simply a user-user similarity problem where I have
> > >
> > > stars instead of users, wavelengths instead of items, and intensities
> > >
> > > instead of ratings/clicks.
> > >
> > >
> > > But I'm having difficulty using mahout's row similarity package (I'm
> new
> > to
> > >
> > > this, and these days astronomers code pretty exclusively in python). I
> > know
> > >
> > > that I must have to 1) create a sparse matrix where each row is a star,
> > >
> > > columns are wavelengths, and the values are intensity, and 2) implement
> > row
> > >
> > > similarity. But I'm just not sure how to do it. Anyone have a good
> > resource
> > >
> > > or be willing to help? I could probably offer some compensation to
> anyone
> > >
> > > that would be willing to provide a little focussed, personalized
> > > assistance.
> > >
> > >
> > > Thanks,
> > >
> > > Jonathan
> > >
> >
>

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