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From Jake Mannix <jake.man...@gmail.com>
Subject Re: understanding vectors
Date Mon, 14 Jan 2013 20:59:01 GMT
I could have sworn we've seen and fixed this bug before, but I guess not.
 Let's get a (failing) unit test in there, and then it should be an easy
fix.

I think nobody runs into this because it's really rare to want to iterate
over all of the entries in a sparse vector - iterateNonZero() is used
almost exclusively for these.


On Mon, Jan 14, 2013 at 12:51 PM, Koert Kuipers <koert@tresata.com> wrote:

> not the same behavior in trunk. SequentialAccessVector.iterator seems to
> behave properly there.
>
> On Mon, Jan 14, 2013 at 3:07 PM, Koert Kuipers <koert@tresata.com> wrote:
>
> > sorry yes i meant 0.7
> >
> > On Mon, Jan 14, 2013 at 12:58 PM, Jake Mannix <jake.mannix@gmail.com
> >wrote:
> >
> >> I think you mean 0.7, right?  Can you see if you get the same behavior
> in
> >> svn trunk?
> >>
> >>
> >> On Mon, Jan 14, 2013 at 9:21 AM, Koert Kuipers <koert@tresata.com>
> wrote:
> >>
> >> > i am using version mahout 7.0
> >> >
> >> > On Mon, Jan 14, 2013 at 10:15 AM, Ted Dunning <ted.dunning@gmail.com>
> >> > wrote:
> >> >
> >> > > Which version are you using?
> >> > >
> >> > > (this misbehavior sounds familiar)
> >> > >
> >> > > iterator() should return all values.
> >> > >
> >> > > iterateNonZero() is allowed to skip zeros.
> >> > >
> >> > > On Mon, Jan 14, 2013 at 6:11 AM, Koert Kuipers <koert@tresata.com>
> >> > wrote:
> >> > >
> >> > > > i am looking at the iterators for DenseVector,
> >> > RandomAcccessSparseVector
> >> > > > and SequentialAccessSparseVector.
> >> > > >
> >> > > > for both DenseVector and RandomAcccessSparseVector the iterator
> >> seems
> >> > to
> >> > > > return all values, including the missing zero values.
> >> > > > for SequentialAccessSparseVector the iterator also returns all
> >> values,
> >> > > but
> >> > > > only up to the last non-missing value!
> >> > > >
> >> > > > is this by design? what is a vector iterator supposed to return
> >> > exactly?
> >> > > i
> >> > > > can't see a logical pattern/consistency. see examples below.
> >> > > > thanks! koert
> >> > > >
> >> > > > scala> val x = new
> >> org.apache.mahout.math.RandomAccessSparseVector(5)
> >> > > > x: org.apache.mahout.math.RandomAccessSparseVector = {}
> >> > > >
> >> > > > scala> x.set(3, 1.0)
> >> > > >
> >> > > > scala> for (item <- x.iterator.asScala) println((item.index,
> >> item.get))
> >> > > > (0,0.0)
> >> > > > (1,0.0)
> >> > > > (2,0.0)
> >> > > > (3,1.0)
> >> > > > (4,0.0)
> >> > > >
> >> > > > scala> val y = new
> >> > org.apache.mahout.math.SequentialAccessSparseVector(5)
> >> > > > y: org.apache.mahout.math.SequentialAccessSparseVector = {
> >> > > >
> >> > > > scala> y.set(3, 1.0)
> >> > > >
> >> > > > scala> for (item <- y.iterator.asScala) println((item.index,
> >> item.get))
> >> > > > (0,0.0)
> >> > > > (1,0.0)
> >> > > > (2,0.0)
> >> > > > (3,1.0)
> >> > > >
> >> > >
> >> >
> >>
> >>
> >>
> >> --
> >>
> >>   -jake
> >>
> >
> >
>



-- 

  -jake

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