Suneel is right. :) Let me explain how this came up: - When clustering, and assigning a point to a cluster, the centroid needs to be updated. - To update the centroid in the nearest neighbor searcher classes, the centroid must first be removed. - To remove the centroid, we get the closest vector (search for it, and it should be itself) and then remove it from the data structures. => However, when the centroid is 0, the nearest vector (which should be itself) has a huge distance (1 rather than 0) and this trips a check.
On Thu, Apr 4, 2013 at 9:46 PM, Sean Owen <sro...@gmail.com> wrote: > It sounds pretty undefined, but I would tend to define the distance as > 0 in this case of course. And that means defining the cosine as 1. > Which class in particular? There are a few implementations of this > distance measure. > > On Thu, Apr 4, 2013 at 7:42 PM, Dan Filimon <dangeorge.fili...@gmail.com> > wrote: > > In the case where both vectors are all zeros, the angle between them is > 0, > > so the cosine is therefore 1 and the so the distance returned should be 0 > > (unless I misunderstood what the distance does). > > > > In Mahout, when calling distance() however, if both the denominator and > > dotProduct are 0 (which is true when both vectors are 0), the returned > > value is 1. > > > > This looks like a bug to me and I would open a JIRA issue and fix it but > I > > want to make sure there's nothing I could possibly be missing. > > > > Thoughts? >
