Clustering implementations are notoriously hard to debug, if only because they are relatively robust so that broken implementations will often produce plausible results.
On 3/14/08 12:58 PM, "Jeff Eastman (JIRA)" <[EMAIL PROTECTED]> wrote: > > [ > https://issues.apache.org/jira/browse/MAHOUT-15?page=com.atlassian.jira.plugin > .system.issuetabpanels:all-tabpanel ] > > Jeff Eastman updated MAHOUT-15: > ------------------------------- > > Attachment: MAHOUT-15c.patch > > Found another defect in the iteration loop. The order of the done test (done = > done && migrate(0.5)) was omitting the canopy migrations once the first one > reported not done. I reversed the elements and now the algorithm converges in > 4 iterations vs 44. I also tweaked the actual migration routine to merge with > only the closest canopy vs. the first one encountered. Finally, I added > another set of values ('/') to the initial image data set and the algorithm > clustered it correctly too: > > ABBBBBBBBC > BABBBBBBCB > BBABBBBCBB > BBBABBCBBB > BBBBACBBBB > BBBBCABBBB > BBBCBBABBB > BBCBBBBABB > BCBBBBBBAB > CBBBBBBBBA > > Note: The values I added had a z=4 value and were clustered separately (C). > When I changed their z value to 9, there were only two remaining canopies (A, > B): > > ABBBBBBBBA > BABBBBBBAB > BBABBBBABB > BBBABBABBB > BBBBAABBBB > BBBBAABBBB > BBBABBABBB > BBABBBBABB > BABBBBBBAB > ABBBBBBBBA > > I still do not know what to call this algorithm, perhaps 'colliding canopies' > or 'coalescing canopies'? Though it has some similarity to mean shift I'd be > surprised if the term applies. > >> Investigate Mean Shift Clustering >> --------------------------------- >> >> Key: MAHOUT-15 >> URL: https://issues.apache.org/jira/browse/MAHOUT-15 >> Project: Mahout >> Issue Type: New Feature >> Components: Clustering >> Reporter: Jeff Eastman >> Assignee: Jeff Eastman >> Attachments: MAHOUT-15a.patch, MAHOUT-15b.patch, MAHOUT-15c.patch >> >> >> "The mean shift algorithm is a nonparametric clustering technique which does >> not require prior knowledge of the number of clusters, and does not constrain >> the shape of the clusters." >> http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/TUZEL1/MeanShift.pdf >> Investigate implementing mean shift clustering using Hadoop
