See MAHOUT-1193. Feel free to grab that code, torture it, and tell us if
it is any good.
If it is useful, we can commit it.
On Thu, Apr 18, 2013 at 3:34 PM, Ted Dunning <ted.dunn...@gmail.com> wrote:
> I hadn't planned to since I don't have cycles to properly test it.
>
> Let me see if I can dig it back up to see if anybody else wants to.
>
> SparseMatrix may be good enough for you.
>
>
> On Thu, Apr 18, 2013 at 2:48 PM, Gokhan Capan <gkhn...@gmail.com> wrote:
>
>> Ted,
>>
>> Are you going to commit this?
>>
>>
>> On Thu, Apr 18, 2013 at 5:18 PM, Ted Dunning <ted.dunn...@gmail.com>
>> wrote:
>>
>> > Actually, I built a BlockSparseMatrix some time ago that does this.
>> >
>> > It was just like our current row sparse matrix except that it allowed
>> for
>> > blocks instead of rows.
>> >
>> > It did assume sparse matrices where the data existed.
>> >
>> > Worked a charm on the app in question.
>> >
>> > It doesn't appear that I committed it.
>> >
>> >
>> >
>> >
>> > On Thu, Apr 18, 2013 at 7:02 AM, Gokhan Capan <gkhn...@gmail.com>
>> wrote:
>> >
>> > > Ok, I'll do that.
>> > >
>> > > Thank you, Jake.
>> > >
>> > >
>> > > On Thu, Apr 18, 2013 at 4:43 AM, Jake Mannix <jake.man...@gmail.com>
>> > > wrote:
>> > >
>> > > > SparseMatrix is implemented as a Map<Integer, Vector>, you could
>> modify
>> > > > that class to allow you to chose between dense or sparse rows at
>> > > > construction time.
>> > > >
>> > > >
>> > > > On Wed, Apr 17, 2013 at 4:01 PM, Robin Anil <robin.a...@gmail.com>
>> > > wrote:
>> > > >
>> > > > > Yes! Yes! Go for it!.
>> > > > > On Apr 17, 2013 5:52 PM, "Gokhan Capan" <gkhn...@gmail.com>
>> wrote:
>> > > > >
>> > > > > > I didn't quite get that, and assuming you tell me to implement
>> it
>> > > > > >
>> > > > > > Thanks
>> > > > > >
>> > > > > >
>> > > > > > On Thu, Apr 18, 2013 at 1:44 AM, Robin Anil <
>> robin.a...@gmail.com>
>> > > > > wrote:
>> > > > > >
>> > > > > > > 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
>> > > > > > > >
>> > > > > > >
>> > > > > >
>> > > > > >
>> > > > > >
>> > > > > > --
>> > > > > > Gokhan
>> > > > > >
>> > > > >
>> > > >
>> > > >
>> > > >
>> > > > --
>> > > >
>> > > > -jake
>> > > >
>> > >
>> > >
>> > >
>> > > --
>> > > Gokhan
>> > >
>> >
>>
>>
>>
>> --
>> Gokhan
>>
>
>
