Good clarification Sean. Diana, I was also referring to this example when 
setting up some of my bigger ALS runs. I don't this particular example is very 
helpful, as it is creating the initial matrix locally in memory before 
parallelizing in spark. So (unless I'm misunderstanding), it is an ok example 
at demonstrating basic spark functionality, but since it is limited by local 
memory you obviously can't demo it on bigger datasets. 

The example at  spark.apache.org/docs/0.9.1/mllib-guide.html I found to be much 
more helpful for good use cases.

-----Original Message-----
From: Sean Owen [mailto:so...@cloudera.com] 
Sent: Monday, April 28, 2014 1:41 PM
To: user@spark.apache.org
Subject: Re: running SparkALS

Yeah you'd have to look at the source code in this case; it's not explained in 
the scaladoc or usage message as far as I can see either.
The args refer specifically to the example of recommending Movies to Users. 
This example makes up a bunch of ratings and then makes recommendations using 
ALS.

M = number of movies in the made-up data U = number of users F = number of 
latent factors in the ALS model iter = number of iterations to run ALS for 
slices = level of parallelism to use on Spark

I'd say that could be explained in the scaladoc at least.

As an aside though, looking at the code, this is not a demo of ALS from MLlib, 
but a different implementation and based on the CERN linear algebra libraries. 
Is this still a good example?
--
Sean Owen | Director, Data Science | London


On Mon, Apr 28, 2014 at 6:30 PM, Diana Carroll <dcarr...@cloudera.com> wrote:
> Hi everyone.  I'm trying to run some of the Spark example code, and 
> most of it appears to be undocumented (unless I'm missing something).  
> Can someone help me out?
>
> I'm particularly interested in running SparkALS, which wants parameters:
> M U F iter slices
>
> What are these variables?  They appear to be integers and the default 
> values are 100, 500 and 10 respectively but beyond that...huh?
>
> Thanks!
>
> Diana
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