I was recently looking through code (I think in text vectors) where code merged very sparse term vectors. If there was a collision, it always picked the first one. The assumption was that they never happened, so it did not matter what it did. For symboic vectors, I can see the virtue of randomly picking one rather than doing arithmetic.
On Thu, Dec 1, 2011 at 7:41 PM, Raphael Cendrillon <[email protected] > wrote: > Thanks. Thats interesting. In what kind of algorithms have you seen a need > for this? > > If I understand correctly you'd like to randomly pick between the two > elements, say with equal probability? I think this wouldn't be too > difficult to implement within the current framework. > > By the way, if you're interested in doing a quick review of the code it > would be really appreciated! It's up on the reviewboard at > https://reviews.apache.org/r/2955/diff/2/ > > On 1 Dec, 2011, at 7:30 PM, "Lance Norskog (Commented) (JIRA)" < > [email protected]> wrote: > > > > > [ > https://issues.apache.org/jira/browse/MAHOUT-880?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13161398#comment-13161398] > > > > Lance Norskog commented on MAHOUT-880: > > -------------------------------------- > > > > Oops sorry. This is about the set of pairwise operators available when > you combine two or more matrices: plus, minus, mean, etc. Another use case > is to just use one of the values. > > > >> Add some matrix method(like addition, subtraction, norm ... etc) to > DistributedRowMatrix > >> > ---------------------------------------------------------------------------------------- > >> > >> Key: MAHOUT-880 > >> URL: https://issues.apache.org/jira/browse/MAHOUT-880 > >> Project: Mahout > >> Issue Type: New Feature > >> Components: Math > >> Affects Versions: 0.6 > >> Reporter: Wangda Tan > >> Priority: Minor > >> Labels: DistributedRowMatrix > >> Attachments: MAHOUT-880.patch > >> > >> > >> I'm a new to Mahout, I didn't find some basic matrix functions. This > make users cannot do many tasks by CLI or API, if user get some result > through existing map-reduce matrix operation (like svd), he cannot do > farther steps. I make a list for it: > >> 1) Addition, Subtraction > >> 2) Norm (like norm-1, norm-2, norm-frobenius) > >> 3) Matrix compare > >> 4) Get lower triangle, upper triangle and diagonal > >> 5) Get identity and zero matrix > >> 6) Put two or matrix to together: A = [A1, A2] > >> 7) More linear equations solver method, like Gaussian elimination > (maybe it's hard to implement) > >> 8) import and export CSV, ARFF ... (this will very useful when user > want to reuse result from or to other applications like MATLAB) > >> I want to know is there any plan to do this, if so, I can make some > efforts to implement these. > > > > -- > > 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 [email protected]
