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From <praveen.pe...@nokia.com>
Subject RE: PFPGrowth - weird output?
Date Fri, 04 Feb 2011 02:44:19 GMT
Hi Vipul,
Frquent patterns are reported per feature which is why you are seeing the two patterns twice.
First one is for feature 1518311 and second one is for feature 1476937.

However both should have the same exact support. I am not sure why you have different support
for the same item set. May be if you send the full output from Mahout as it is we could take
a look.

Are you running on multi node Hadoop cluster. If so did you read all the output files?

Praveen
________________________________________
From: ext Vipul Pandey [vipandey@gmail.com]
Sent: Thursday, February 03, 2011 8:21 PM
To: user@mahout.apache.org
Subject: PFPGrowth - weird output?

Hi all!

I'm trying to run PFPgrowth on my data and this is an output I get. (Please
note that I parse the output in frequentpatterns folder and generate this
output with the support followed by the itemset)

support : Itemset
*234     1518311    1476937  *
235     55843184
238     1238079
244     34541
247     4516454
252     106478
252     670864
*254     1476937   1518311  *

You can see that two items are reported twice (*1518311    1476937*) with
different supports.

And below are all the occurance of these two items together .... if you
notice it has all the permutations of the three items (*1476937* *720020* *
1518311*  )

22 *1476937* 720020 *1518311*
30 *1518311* *1476937* 720020
30 720020 *1518311* *1476937*
34 720020 *1476937* *1518311*
38 *1518311* 720020 *1476937*
42 *1476937* *1518311* 720020
234 *1518311* *1476937*
254 *1476937* *1518311*

Does this mean if I have to get the support of just the the pair  (*1476937*
 *1518311*  ) I will have to add all of them up !?

Even in that case ... this total comes out to *684* and if I count the
number of co-ocurrances of these two items in the original baskets the
support is *766*? Why's there a difference? any idea?


Thanks!
Vipul

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