To use a combiner, TupleWritable should be fine. I have not used it. But it will copy the entire vector. You would want to minimize this. If this is a big problem, you can do an ugly trick: you store the counter as the key value, but make a custom Writable that always returns 'this equals the other'. So, all of your counters have the same key and thus all vectors go to the same reducer.
On Sun, Dec 11, 2011 at 8:14 PM, Raphael Cendrillon (Commented) (JIRA) <j...@apache.org> wrote: > > [ > https://issues.apache.org/jira/browse/MAHOUT-923?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13167341#comment-13167341 > ] > > Raphael Cendrillon commented on MAHOUT-923: > ------------------------------------------- > > Thanks Lance. A combiner is definitely the next step. One question, is there > already a writable for tuples of e.g. int and Vector, or should I just write > one from scratch? I know there is TupleWritable, but from what I've read > online it's better to avoid that unless you're doing a multiple input join. > > Regarding the class for the output vector, are you saying that instead of > inhereting the class from the rows of the DistributedRowMatrix you'd rather > be able to specify this manually? > > > >> Row mean job for PCA >> -------------------- >> >> Key: MAHOUT-923 >> URL: https://issues.apache.org/jira/browse/MAHOUT-923 >> Project: Mahout >> Issue Type: Improvement >> Components: Math >> Affects Versions: 0.6 >> Reporter: Raphael Cendrillon >> Assignee: Raphael Cendrillon >> Fix For: Backlog >> >> Attachments: MAHOUT-923.patch >> >> >> Add map reduce job for calculating mean row (column-wise mean) of a >> Distributed Row Matrix for use in PCA. > > -- > This message is automatically generated by JIRA. > If you think it was sent incorrectly, please contact your JIRA > administrators: > https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa > For more information on JIRA, see: http://www.atlassian.com/software/jira > > -- Lance Norskog goks...@gmail.com
