On Mon, Jul 21, 2014 at 3:35 PM, Pat Ferrel <[email protected]> wrote:
> If you do drm.plus(1) this converts to a dense matrix, which is what the > result must be anyway, and does add the scalar to all rows, even missing > ones. > > Pat, I mentioned this in my previous email already. drm.plus(1) completely misses the point. It converts DRM into an in-core matrix and applies plus() method on Matrix. The result is a Matrix, not DRM. drm.plus(1) is EXACTLY the same as: Matrix m = drm.collect() m.plus(1) The implicit def drm2InCore() syntactic sugar is probably turning out to be dangerous in this case, in terms of hinting the wrong meaning. Thanks > On Jul 21, 2014, at 3:23 PM, Dmitriy Lyubimov <[email protected]> wrote: > > perhaps just compare row count with max(key)? that's exactly what lazy > nrow() currently does in this case. > > > On Mon, Jul 21, 2014 at 3:21 PM, Dmitriy Lyubimov <[email protected]> > wrote: > > > > > ok. so it should be easy to fix at least everything but elementwise > scalar > > i guess. > > > > Since the notion of "missing rows" is only defined for int-keyed > datasets, > > then ew scalar technically should work for non-int keyed datasets > already. > > > > as for int-keyed datasets, i am not sure what is the best strategy. > > Obviously, one can define sort of normalization/validation of int-keyed > > dataset routine, but it would be fairly expensive to run "just because". > > Perhaps there's a cheap test (as cheap as row count job) to run to test > for > > int keys consistency when matrix is first created. > > > > > > > > On Mon, Jul 21, 2014 at 3:12 PM, Anand Avati <[email protected]> wrote: > > > >> > >> > >> > >> On Mon, Jul 21, 2014 at 3:08 PM, Dmitriy Lyubimov <[email protected]> > >> wrote: > >> > >>> > >>> > >>> > >>> On Mon, Jul 21, 2014 at 3:06 PM, Anand Avati <[email protected]> > wrote: > >>> > >>>> Dmitriy, comments inline - > >>>> > >>>> On Jul 21, 2014, at 1:12 PM, Dmitriy Lyubimov <[email protected]> > >>>> wrote: > >>>> > >>>>> And no, i suppose it is ok to have "missing" rows even in case of > >>>>> int-keyed matrices. > >>>>> > >>>>> there's one thing that you probably should be aware in this context > >>>>> though: many algorithms don't survive empty (row-less) partitions, in > >>>>> whatever way they may come to be. Other than that, I don't feel > every row > >>>>> must be present -- even if there's implied order of the rows. > >>>>> > >>>> > >>>> I'm not sure if that is necessarily true. There are three operators > >>>> which break pretty badly with with missing rows. > >>>> > >>>> AewScalar - operation like A + 1 is just not applied on the missing > >>>> row, so the final matrix will have 0's in place of 1s. > >>>> > >>> > >>> Indeed. i have no recourse at this point. > >>> > >>> > >>>> > >>>> AewB, CbindAB - function after cogroup() throws exception if a row was > >>>> present on only one matrix. So I guess it is OK to have missing rows > as > >>>> long as both A and B have the exact same missing row set. Somewhat > >>>> quirky/nuanced requirement. > >>>> > >>> > >>> Agree. i actually was not aware that's a cogroup() semantics in spark. > I > >>> though it would have an outer join semantics (as in Pig, i believe). > Alas, > >>> no recourse at this point either. > >>> > >> > >> The exception is actually during reduceLeft after cogroup(). Cogroup() > >> itself is probably an outer-join. > >> > >> > >> > > > >
