[Numpy-discussion] consensus (was: NA masks in the next numpy release?)

Charles R Harris charlesr.harris@gmail....
Fri Oct 28 20:32:19 CDT 2011


On Fri, Oct 28, 2011 at 6:45 PM, Wes McKinney <wesmckinn@gmail.com> wrote:

> On Fri, Oct 28, 2011 at 7:53 PM, Benjamin Root <ben.root@ou.edu> wrote:
> >
> >
> > On Friday, October 28, 2011, Matthew Brett <matthew.brett@gmail.com>
> wrote:
> >> Hi,
> >>
> >> On Fri, Oct 28, 2011 at 4:21 PM, Ralf Gommers
> >> <ralf.gommers@googlemail.com> wrote:
> >>>
> >>>
> >>> On Sat, Oct 29, 2011 at 12:37 AM, Matthew Brett <
> matthew.brett@gmail.com>
> >>> wrote:
> >>>>
> >>>> Hi,
> >>>>
> >>>> On Fri, Oct 28, 2011 at 3:14 PM, Charles R Harris
> >>>> <charlesr.harris@gmail.com> wrote:
> >>>> >
> >>>> >
> >>>> > On Fri, Oct 28, 2011 at 3:56 PM, Matthew Brett
> >>>> > <matthew.brett@gmail.com>
> >>>> > wrote:
> >>>> >>
> >>>> >> Hi,
> >>>> >>
> >>>> >> On Fri, Oct 28, 2011 at 2:43 PM, Matthew Brett
> >>>> >> <matthew.brett@gmail.com>
> >>>> >> wrote:
> >>>> >> > Hi,
> >>>> >> >
> >>>> >> > On Fri, Oct 28, 2011 at 2:41 PM, Charles R Harris
> >>>> >> > <charlesr.harris@gmail.com> wrote:
> >>>> >> >>
> >>>> >> >>
> >>>> >> >> On Fri, Oct 28, 2011 at 3:16 PM, Nathaniel Smith <njs@pobox.com
> >
> >>>> >> >> wrote:
> >>>> >> >>>
> >>>> >> >>> On Tue, Oct 25, 2011 at 2:56 PM, Travis Oliphant
> >>>> >> >>> <oliphant@enthought.com>
> >>>> >> >>> wrote:
> >>>> >> >>> > I think Nathaniel and Matthew provided very
> >>>> >> >>> > specific feedback that was helpful in understanding other
> >>>> >> >>> > perspectives
> >>>> >> >>> > of a
> >>>> >> >>> > difficult problem.     In particular, I really wanted
> >>>> >> >>> > bit-patterns
> >>>> >> >>> > implemented.    However, I also understand that Mark did
> quite
> >>>> >> >>> > a
> >>>> >> >>> > bit
> >>>> >> >>> > of
> >>>> >> >>> > work
> >>>> >> >>> > and altered his original designs quite a bit in response to
> >>>> >> >>> > community
> >>>> >> >>> > feedback.   I wasn't a major part of the pull request
> >>>> >> >>> > discussion,
> >>>> >> >>> > nor
> >>>> >> >>> > did I
> >>>> >> >>> > merge the changes, but I support Charles if he reviewed the
> >>>> >> >>> > code
> >>>> >> >>> > and
> >>>> >> >>> > felt
> >>>> >> >>> > like it was the right thing to do.  I likely would have done
> >>>> >> >>> > the
> >>>> >> >>> > same
> >>>> >> >>> > thing
> >>>> >> >>> > rather than let Mark Wiebe's work languish.
> >>>> >> >>>
> >>>> >> >>> My connectivity is spotty this week, so I'll stay out of the
> >>>> >> >>> technical
> >>>> >> >>> discussion for now, but I want to share a story.
> >>>> >> >>>
> >>>> >> >>> Maybe a year ago now, Jonathan Taylor and I were debating what
> >>>> >> >>> the
> >>>> >> >>> best API for describing statistical models would be -- whether
> we
> >>>> >> >>> wanted something like R's "formulas" (which I supported), or
> >>>> >> >>> another
> >>>> >> >>> approach based on sympy (his idea). To summarize, I thought his
> >>>> >> >>> API
> >>>> >> >>> was confusing, pointlessly complicated, and didn't actually
> solve
> >>>> >> >>> the
> >>>> >> >>> problem; he thought R-style formulas were superficially simpler
> >>>> >> >>> but
> >>>> >> >>> hopelessly confused and inconsistent underneath. Now,
> obviously,
> >>>> >> >>> I
> >>>> >> >>> was
> >>>> >> >>> right and he was wrong. Well, obvious to me, anyway... ;-) But
> it
> >>>> >> >>> wasn't like I could just wave a wand and make his arguments go
> >>>> >> >>> away,
> >>>> >> >>> no I should point out that the implementation hasn't - as far
> as
> >>>> >> >>> I can
> >> see - changed the discussion.  The discussion was about the API.
> >> Implementations are useful for agreed APIs because they can point out
> >> where the API does not make sense or cannot be implemented.  In this
> >> case, the API Mark said he was going to implement - he did implement -
> >> at least as far as I can see.  Again, I'm happy to be corrected.
> >>
> >>>> In saying that we are insisting on our way, you are saying,
> implicitly,
> >>>> 'I
> >>>> am not going to negotiate'.
> >>>
> >>> That is only your interpretation. The observation that Mark compromised
> >>> quite a bit while you didn't seems largely correct to me.
> >>
> >> The problem here stems from our inability to work towards agreement,
> >> rather than standing on set positions.  I set out what changes I think
> >> would make the current implementation OK.  Can we please, please have
> >> a discussion about those points instead of trying to argue about who
> >> has given more ground.
> >>
> >>> That commitment would of course be good. However, even if that were
> >>> possible
> >>> before writing code and everyone agreed that the ideas of you and
> >>> Nathaniel
> >>> should be implemented in full, it's still not clear that either of you
> >>> would
> >>> be willing to write any code. Agreement without code still doesn't help
> >>> us
> >>> very much.
> >>
> >> I'm going to return to Nathaniel's point - it is a highly valuable
> >> thing to set ourselves the target of resolving substantial discussions
> >> by consensus.   The route you are endorsing here is 'implementor
> >> wins'.   We don't need to do it that way.  We're a mature sensible
> >> bunch of adults who can talk out the issues until we agree they are
> >> ready for implementation, and then implement.  That's all Nathaniel is
> >> saying.  I think he's obviously right, and I'm sad that it isn't as
> >> clear to y'all as it is to me.
> >>
> >> Best,
> >>
> >> Matthew
> >>
> >
> > Everyone, can we please not do this?! I had enough of adults doing finger
> > pointing back over the summer during the whole debt ceiling debate.  I
> think
> > we can all agree that we are better than the US congress?
> >
> > Forget about rudeness or decision processes.
> >
> > I will start by saying that I am willing to separate ignore and absent,
> but
> > only on the write side of things.  On read, I want a single way to
> identify
> > the missing values.  I also want only a single way to perform
> calculations
> > (either skip or propagate).
> >
> > An indicator of success would be that people stop using NaNs and magic
> > numbers (-9999, anyone?) and we could even deprecate nansum(), or at
> least
> > strongly suggest in its docs to use NA.
>
> Well, I haven't completely made up my mind yet, will have to do some
> more prototyping and playing (and potentially have some of my users
> eat the differently-flavored dogfood), but I'm really not very
> satisfied with the API at the moment. I'm mainly worried about the
> abstraction leaking through to pandas users (this is a pretty large
> group of people judging by # of downloads).
>
> The basic position I'm in is that I'm trying to push Python into a new
> space, namely mainstream data analysis and statistical computing, one
> that is solidly occupied by R and other such well-known players. My
> target users are not computer scientists. They are not going to invest
> in understanding dtypes very deeply or the internals of ndarray. In
> fact I've spent a great deal of effort making it so that pandas users
> can be productive and successful while having very little
> understanding of NumPy. Yes, I essentially "protect" my users from
> NumPy because using it well requires a certain level of sophistication
> that I think is unfair to demand of people. This might seem totally
> bizarre to some of you but it is simply the state of affairs. So far I
> have been successful because more people are using Python and pandas
> to do things that they used to do in R. The NA concept in R is dead
> simple and I don't see why we are incapable of also implementing
> something that is just as dead simple. To we, the scipy elite let's
> call us, it seems simple: "oh, just pass an extra flag to all my array
> constructors!" But this along with the masked array concept is going
> to have two likely outcomes:
>
> 1) Create a great deal more complication in my already very large codebase
>
> and/or
>
> 2) force pandas users to understand the new masked arrays after I've
> carefully made it so they can be largely ignorant of NumPy
>
> The mostly-NaN-based solution I've cobbled together and tweaked over
> the last 42 months actually *works really well*, amazingly, with
> relatively little cost in code complexity. Having found a reasonably
> stable equilibrium I'm extremely resistant to upset the balance.
>
> So I don't know. After watching these threads bounce back and forth
> I'm frankly not all that hopeful about a solution arising that
> actually addresses my needs.
>

But Wes, what *are* your needs? You keep saying this, but we need examples
of how you want to operate and how numpy fails. As to dtypes, internals, and
all that, I don't see any of that in the current implementation, unless you
mean the maskna and skipna keywords. I believe someone on the previous
thread mentioned a way to deal with that.

Chuck
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