I am using Mahout every day on Spark 1.3.1.

Try https://github.com/pferrel/mahout/tree/spark-1.3, which is the one I’m 
using. Let me know if you still have the problem and include the stack trace. 
I’ve been using cooccurrence, which is closely related to rowSimilarity.

> Third, what would be the mathematical implications if I run 
> SimilarityAnalysis.cooccurrencesIDSs() with a list of (<tag>,<document_id>) 
> pairs. Would the results be sound, or does that make absolutely no sense? 
> Would it be beneficial even as only a troubleshooting step?

cooccurrence calculates llr(A’A), and rowSimilarity is doing llr(AA’). The 
input you are talking about is A’ so you would be doing llr((A’)’(A’)) and so 
should produce the same results but let’s get it working. I’ll look at it 
either tomorrow or this weekend. If you have any stack trace using the above 
branch, let me know.

BTW what Dmitriy said is correct, IntelliJ is often not able to determine every 
decoration function available.


On Jul 9, 2015, at 12:02 PM, Hegner, Travis <[email protected]> wrote:

FYI, I just tested against the latest spark-1.3 version I found at: 
https://github.com/andrewpalumbo/mahout/tree/MAHOUT-1653-shell-master

I am getting the exact results described below.

Thanks again!

Travis

-----Original Message-----
From: Hegner, Travis [mailto:[email protected]]
Sent: Thursday, July 09, 2015 10:25 AM
To: '[email protected]'
Subject: RowSimilarity API -- illegal argument exception from 
org.apache.mahout.math.stats.LogLikelihood.logLikelihoodRatio()

Hello list,

I am having some trouble getting a SimilarityAnalysis.rowSimilarityIDS() job to 
run. First some info on my environment:

I'm running hadoop with cloudera 5.4.2 with their built in spark on yarn setup 
it's pretty much an OOTB setup, but it has been upgraded many times since 
probably CDH4.8 or so. It's running spark 1.3.0 (perhaps some 1.3.1 commits 
merged in from what I've read about cloudera's versioning). I have my own fork 
of mahout which is currently just a mirror of 'github.com:pferrel/spark-1.3'. 
I'm very comfortable making changes, compiling, and using my version of the 
library should your suggestions lead me in that direction. I am still pretty 
new to scala, so I have a hard time wrapping my head around what some of the 
syntactic sugars actually do, but I'm getting there.

I'm successfully getting my data transformed to an RDD that essentially looks 
like (<document_id>, <tag>), creating an IndexedDataSet with that, and feeding 
that into SimilarityAnalysis.rowSimilarityIDS(). I've been able to narrow the 
issue down to a specific case:

Let's say I have the following records (among others) in my RDD:

...
(doc1, tag1)
(doc2, tag1)
...

doc1, and doc2 have no other tags, but tag1 may exist on many other documents. 
The rest of my dataset has many other doc/tag combinations, but I've narrowed 
down the issue to seemingly only occur in this case. I've been able to trace 
down that the java.lang.IllegalArgumentException is occuring because k21 is < 0 
(i.e. "numInteractionsWithB = 0" and "numInteractionsWithAandB = 1") when 
calling LogLikelihood.logLikelihoodRatio() from 
SimilarityAnalysis.logLikelihoodRatio().

Speculating a bit, I see that in SimilarityAnalysys.rowSimilarity() on the line 
(163 in my branch):

val bcastInteractionsPerItemA = drmBroadcast(drmA.numNonZeroElementsPerRow)

...my IDE (intellij) complains that it cannot resolve 
"drmA.numNonZeroElementsPerRow", however the library compiles successfully. 
Tracing the codepath shows that if that value is not being correctly populated, 
it would have a direct impact on the values used in logLikelihoodRatio(). That 
said, it seems to only fail in this very particular case.

I should note that I can run SimilarityAnalysis.cooccurrencesIDSs() 
successfully with a single list of (<user_id>, <item_id>) pairs of my own data.

I have 3 questions given this scenario:

First, am I using the proper branch of code for attempting to run on a spark 
1.3 cluster? I've read about a "joint effort" for spark 1.3, and this was the 
only branch I could find for it.

Second, Is anyone able to shed some light on the above error? Is drmA not a 
correct type, or does that method no longer apply to that type?

Third, what would be the mathematical implications if I run 
SimilarityAnalysis.cooccurrencesIDSs() with a list of (<tag>,<document_id>) 
pairs. Would the results be sound, or does that make absolutely no sense? Would 
it be beneficial even as only a troubleshooting step?

Thanks in advance for any help you may be able to provide!

Travis Hegner

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