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Posted to dev@mahout.apache.org by "Robin Anil (JIRA)" <ji...@apache.org> on 2011/03/13 19:56:59 UTC
[jira] Resolved: (MAHOUT-617) FPGrowth/PFPGrowth giving out wrong
results.
[ https://issues.apache.org/jira/browse/MAHOUT-617?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Robin Anil resolved MAHOUT-617.
-------------------------------
Resolution: Not A Problem
> FPGrowth/PFPGrowth giving out wrong results.
> ---------------------------------------------
>
> Key: MAHOUT-617
> URL: https://issues.apache.org/jira/browse/MAHOUT-617
> Project: Mahout
> Issue Type: Bug
> Components: Frequent Itemset/Association Rule Mining
> Affects Versions: 0.4
> Environment: Mac OS X, Linux
> Reporter: Vipul Pandey
> Assignee: Robin Anil
> Labels: AssociationMining, FPGrowth, FrequentItemsets
> Attachments: XY, XYZ
>
>
> FPGrowth reports the support of itemsets individually - in that - if Item X appears "individually" 12 times and appears with item Y 10 times (a total of 22 times) AND item Y appears "individually" 4 times (a total of 14 times) then this is what the output will be (say for min-support 2)
> 12 X
> 10 XY
> 4 Y
> Instead of
> 22 X
> 10 XY
> 14 Y
> Also, because of this If the minimum support is 5 then the output will look like :
> 12 X
> 10 X Y
> Thus totally Ignoring Y
> if the minimum support is 11 then the output will look like
> 12 X
> again Ignoring Y
> if the minimum support is 13 then there will be NO output. even though all the way along Xs support was 22 and Y's was 14
> Even if we want to show just the maximal itemsets (although i would like to see ALL the frequent itemsets - maximal or not) this output is wrong as with a support of 13 we should still have seen X(22) and Y(14)
> Now Say you add XYZ 11 times
> for support 1 you'd see
> 12 X
> 10 X Y
> 11 X Y Z
> 4 Y
> And for support 11 you'd see
> 12 X
> 11 X Y Z
> Although I'd expect the output (for both s=1 & s=11) to be
> 33 X
> 25 Y
> 21 XY
> 11 Z
> 11 XZ
> 11 YZ
> 11 XYZ
> attached are the sample inputs:
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