Make one?
On Apr 17, 2013 5:37 PM, "Gokhan Capan" <gkhn...@gmail.com> wrote:
> Robin,
>
> Aren't SparseRowMatrix rows are sparse vectors? In my use case row vectors
> don't need to be sparse, they are either full or empty.
>
>
> On Thu, Apr 18, 2013 at 1:32 AM, Robin Anil <robin.a...@gmail.com> wrote:
>
> > SparseRowMatrix?
> > On Apr 17, 2013 5:26 PM, "Gokhan Capan" <gkhn...@gmail.com> wrote:
> >
> > > Hi,
> > >
> > > Using Mahout Matrix interface I want to represent some data where the
> row
> > > vector is dense iff an instance is associated to this row index, empty
> > > otherwise. The max possible index for rows (a.k.a. rowSize) is defined.
> > >
> > > I never query the matrix by column.
> > > I want to be able to add rows if the rowId is not larger than the
> > rowSize.
> > >
> > > Does a matrix implementation exist that I can use, or should I write
> one?
> > >
> > > Not to cause an XY problem, here is the particular use case:
> > > I row-index a latent factor matrix (for recommendation) with userIDs
> (and
> > > itemIDs for the other matrix). I need fast access to a row vector (to
> > > estimate a score for a user-item pair)
> > >
> > > I tried a SparseColumnMatrix, which degrades -it is designed for fast
> > > access by column- the performance. I may use a DenseMatrix, which would
> > > either bring a memory overhead (by allocating row vectors for empty
> > rows),
> > > or result in losing the ability to add new rows (if I map the userIds
> to
> > > {1,2,...,noOfCurrentUsers} space)
> > >
> > > Thanks
> > >
> > > --
> > > Gokhan
> > >
> >
>
>
>
> --
> Gokhan
>
