On Fri, Nov 4, 2011 at 10:33 PM, T J <tjhn...@gmail.com> wrote: > On Fri, Nov 4, 2011 at 8:03 PM, Nathaniel Smith <n...@pobox.com> wrote: > >> On Fri, Nov 4, 2011 at 7:43 PM, T J <tjhn...@gmail.com> wrote: >> > On Fri, Nov 4, 2011 at 6:31 PM, Pauli Virtanen <p...@iki.fi> wrote: >> >> An acid test for proposed rules: given two arrays `a` and `b`, >> >> >> >> a = [1, 2, IGNORED(3), IGNORED(4)] >> >> b = [10, IGNORED(20), 30, IGNORED(40)] >> [...] >> > (A1) Does unmask(a+b) == unmask(b + a) ? >> > >> > Yes. They both equal: >> > >> > unmask([11, IGNORED(22), IGNORED(33), IGNORED(44)]) >> > = >> > [11, 22, 33, 44] >> >> Again, I really don't think you're going to be able to sell an API where >> [2] + [IGNORED(20)] == [IGNORED(22)] >> I mean, it's not me you have to convince, it's Gary, Pierre, maybe >> Benjamin, Lluís, etc. So I could be wrong. But you might want to >> figure that out first before making plans based on this... >> > > But this is how np.ma currently does it, except that it doesn't compute > the payload---it just calls it IGNORED. > And it seems that this generalizes the way people want it to: > > >>> z = [2, 4] + [IGNORED(20), 3] > >>> z > [IGNORED(24), 7] > >>> z.sum(skip_ignored=True) # True could be the default > 7 > >>> z.sum(skip_ignored=False) > IGNORED(31) > > I guess I am confused because it seems that you implicitly used this same > rule here: > > Say we have > >>> a = np.array([1, IGNORED(2), 3]) > > >>> b = np.array([10, 20, 30]) > (Here's I'm using IGNORED(2) to mean a value that is currently > ignored, but if you unmasked it it would have the value 2.) > > Then we have: > > # non-propagating **or** propagating, doesn't matter: > > >>> a + 2 > > [3, IGNORED(2), 5] > > > That is, element-wise, you had to have done: > > IGNORED(2) + 2 --> IGNORED(2). > > I said it should be equal to IGNORED(4), but the result is still some form > of ignore. Sorry if I am missing the bigger picture at this point....its > late and a Fri. > > > This scheme is actually somewhat intriguing. Not totally convinced, by intrigued. Unfortunately, I fell behind in the postings by having dinner... We probably should start a new thread soon with a bunch of this stuff solidified and stated to give others a chance to hop back into the game. Maybe a table of some sort with pros/cons (mathematically speaking, deferring implementation details for later).
I swear, if we can get this to make sense... we should have a Nobel prize or something. Ben Root
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