On Tue, 2019-06-25 at 17:00 -0400, Marten van Kerkwijk wrote: > Hi Kirill, others, > > Indeed, it is becoming long! That said, while initially I was quite > charmed by Eric's suggestion of deprecating and then changing `.T`, I > think the well-argued opposition to it has changed my opinion. > Perhaps most persuasive to me was Matthew's point just now that code > (or a code snippet) that worked on an old numpy should not silently > do something different on a new numpy (unless the old behaviour was a > true bug, of course; but here `.T` has always had a very well-defined > meaning - even though you are right that the documentation does not > exactly lead the novice user away from using it for matrix transpose! > If someone has the time to open a PR that clarifies it.........). > > Note that I do agree with the sentiment that the deprecation/change > would likely expose some hidden bugs - and, as noted, it is hard to > know where those bugs are if they are hidden! (FWIW, I did find some > in astropy's coordinate implementation, which was initially written > for scalar coordinates where `.T` worked was just fine; as a result, > astropy gained a `matrix_transpose` utility function.) Still, it does > not quite outweigh to me the disadvantages enumerated. >
True, eventually switching is much more problematic than only deprecation, and yes, I guess the last step is likely forbidding. I do not care too much, but the at least the deprecation/warning does not seem too bad to me unless it is really widely used for high dimensions. Sure, it requires to touch code and may make it uglier, but a change requiring to touch a fair amount of scripts is not all that uncommon, especially if it can find some bugs (e.g. for me scipy.misc.factorial moving for example meant I had to change a lot of scripts, annoying but I could live with it). Although, I might prefer to spend our "force users to do annoying code changes" chips on better things. And I guess there may not be much of a point in a mere deprecation. > One thing seems clear: if `.T` is out, that means `.H` is out as well > (at least as a matrix transpose, the only sensible meaning I think it > has). Having `.H` as a conjugate matrix transpose would just cause > more confusion about the meaning of `.T`. > I tend to agree, the only way that could work seems if T was deprecated for high dimensions. > For the names, my suggestion of lower-casing the M in the initial > one, i.e., `.mT` and `.mH`, so far seemed most supported (and I think > we should discuss *assuming* those would eventually involve not > copying data; let's not worry about implementation details). It would be a nice assumption, but as I said, I do see an issue with object array support. Which makes it likely that `.H` could only be supported on some dtypes (similar to `.real/.imag`). (Strictly speaking it would be possible to make a ConugateObject dtype and define casting for it, I have some doubt that the added complexity is worth it though). The no-copy conjugate is a cool idea but ultimately may be a bit too cool? > So, specific items to confirm: > > 1) Is this a worthy addition? (certainly, their existence would > reduce confusion about `.T`... so far, my sense is tentative yes) > > 2) Are `.mT` and `.mH` indeed the consensus? [1] > It is likely the only reasonable option, unless you make `H` object which does `arr_like**H` but I doubt that is a good idea. > 3) What, if anything, should these new properties do for 0-d and 1-d > arrays: pass through, change shape, or error? (logically, I think > *new* properties should never emit warnings: either do something or > error). <snip> > Marten > > [1] Some sadness about mᵀ and mᴴ - but, then, there is > http://www.modernemacs.com/post/prettify-mode/ > Hehe, you are using a block for Phonetic Extensions, and that block has a second H which looks the same on my font but is Cyrillic. Lucky us, we could make one of them for row vectors and the other for column vectors ;). - Sebastian > On Tue, Jun 25, 2019 at 4:17 PM Kirill Balunov < > kirillbalu...@gmail.com> wrote: > > вт, 25 июн. 2019 г. в 21:20, Cameron Blocker < > > cameronjbloc...@gmail.com>: > > > It seems to me that the general consensus is that we shouldn't be > > > changing .T to do what we've termed matrix transpose or conjugate > > > transpose. > > > > > > > Reading through this thread, I can not say that I have the same > > opinion - at first, many looked positively at the possibility of > > change - `arr.T` to mean a transpose of the last two dimensions by > > default, and then people start discussing several different (albeit > > related) topics at once. So, I want to point out that it is rather > > difficult to follow what is currently discussed in this thread, > > probably because several different (albeit related) topics are > > being discussed at once. I would suggest at first discuss `arr.T` > > change, because other topics somewhat depend on that > > (`arr.MT`/`arr.CT`/`arr.H` and others). > > > > p.s: Documentation about `.T` shows only two examples, for 1d - > > to show that it works and for 2d case. Maybe it means something? > > (especially for new `numpy` users. ) > > > > with kind regards, > > -gdg > > _______________________________________________ > > NumPy-Discussion mailing list > > NumPy-Discussion@python.org > > https://mail.python.org/mailman/listinfo/numpy-discussion > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@python.org > https://mail.python.org/mailman/listinfo/numpy-discussion
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