Some of generated patterns have support higher than in reality
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Key: MAHOUT-625
URL: https://issues.apache.org/jira/browse/MAHOUT-625
Project: Mahout
Issue Type: Bug
Components: Frequent Itemset/Association Rule Mining
Affects Versions: 0.4
Reporter: Jaroslaw Odzga
Priority: Critical
It turnes out that some of generated patterns have incorrect support. The
returned support is slightly higher than the true one.
I attached the test, which proves that FPGrowth has a bug. Test is using data
(retail) found here: http://fimi.ua.ac.be/data/
The pattern (36, 39, 41) occurs in the transactions 572 times (this is also
calculated in test), but the FPGrowth returns pattern (36, 39, 41) with support
573.
Please note that mentioned pattern is not the only one with incorrect support -
the test only point out one example to hace something to focus on. There is
plenty more patterns with support higher than the real one. The biggest
difference I noticed was support 8 higher than the real one for one of patterns.
Please find attached failing unit test - it's actually a maven project, which
contains test data and is ready to run.
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