The reason is that sparse implementations may have recorded a non-zero that later got assigned a zero, but they didn't bother to remove the memory cell.
On Thu, Jun 12, 2014 at 9:50 AM, Sebastian Schelter <s...@apache.org> wrote: > I'm a bit lost in this discussion. Why do we assume that > getNumNonZeroElements() on a Vector only returns an upper bound? The code > in AbstractVector clearly returns the non-zeros only: > > int count = 0; > Iterator<Element> it = iterateNonZero(); > while (it.hasNext()) { > if (it.next().get() != 0.0) { > count++; > } > } > return count; > > On the other hand, the internal code seems broken here, why does > iterateNonZero potentially return 0's? > > --sebastian > > > > > > > On 06/12/2014 06:38 PM, ASF GitHub Bot (JIRA) wrote: > >> >> [ https://issues.apache.org/jira/browse/MAHOUT-1464?page= >> com.atlassian.jira.plugin.system.issuetabpanels:comment- >> tabpanel&focusedCommentId=14029345#comment-14029345 ] >> >> ASF GitHub Bot commented on MAHOUT-1464: >> ---------------------------------------- >> >> Github user dlyubimov commented on the pull request: >> >> https://github.com/apache/mahout/pull/12#issuecomment-45915940 >> >> fix header to say MAHOUT-1464, then hit close and reopen, it will >> restart the echo. >> >> >> Cooccurrence Analysis on Spark >>> ------------------------------ >>> >>> Key: MAHOUT-1464 >>> URL: https://issues.apache.org/jira/browse/MAHOUT-1464 >>> Project: Mahout >>> Issue Type: Improvement >>> Components: Collaborative Filtering >>> Environment: hadoop, spark >>> Reporter: Pat Ferrel >>> Assignee: Pat Ferrel >>> Fix For: 1.0 >>> >>> Attachments: MAHOUT-1464.patch, MAHOUT-1464.patch, >>> MAHOUT-1464.patch, MAHOUT-1464.patch, MAHOUT-1464.patch, MAHOUT-1464.patch, >>> run-spark-xrsj.sh >>> >>> >>> Create a version of Cooccurrence Analysis (RowSimilarityJob with LLR) >>> that runs on Spark. This should be compatible with Mahout Spark DRM DSL so >>> a DRM can be used as input. >>> Ideally this would extend to cover MAHOUT-1422. This cross-cooccurrence >>> has several applications including cross-action recommendations. >>> >> >> >> >> -- >> This message was sent by Atlassian JIRA >> (v6.2#6252) >> >> >