[Wheel-builders] Questions re: scipy / skimage wheels on Windows

[Ralf Gommers]

On Mon, Mar 21, 2016 at 7:16 AM, Ralf Gommers <ralf.gommers at gmail.com>
wrote:

>
>
> On Sun, Mar 20, 2016 at 11:30 PM, Nathaniel Smith <njs at pobox.com> wrote:
>
>> On Sun, Mar 20, 2016 at 2:03 PM, Stéfan van der Walt
>> <stefanv at berkeley.edu> wrote:
>> > Hi, everyone
>> >
>> > I would like to distribute scikit-image wheels on Windows.  To build
>> > these I require numpy and scipy, but where they come from is not too
>> > important.
>> >
>> > However, we have a bigger problem when it comes to users installing
>> > the skimage wheels, because they would also need numpy and scipy
>> > wheels to be available.
>> >
>> > From what I understand, we currently have the
>> > tools for building these onr 2.7 and 3.4, but not on 3.5.
>> >
>> > What is the latest state of things, and what is my current best course
>> > of action?
>>
>> For scipy that's pretty much the state of things, yeah. (Or, we're on
>> the verge of being able to post 2.7 and 3.4 scipy wheels on Windows --
>> there's some tests of that happening right now on the mingwpy mailing
>> list.) For numpy we already have 2.7 / 3.4 / 3.5 wheels uploaded
>> (using somewhat-slow BLAS, but they work).
>>
>> As for your best course of action, though, I don't think the
>> availability of numpy/scipy wheels changes anything?
>>
>> For 'pip install scikit-image' to work when only an sdist is available
>> (the current situation), then numpy and scipy need to be already
>> installed (IIUC).
>>
>> For 'pip install scikit-image' to to work when a wheel is available
>> (the hopeful future situation), then numpy and scipy need to be
>> either:
>> - available as wheels
>> - automatically buildable (very unlikely on windows)
>> - already installed
>>
>> So it seems like uploading scikit-image wheels right now will only
>> improve the range of things that work. In particular, they'll mean
>> that 'pip install scikit-image' starts working usefully for people who
>> have already installed numpy and scipy via Gohlke's builds, or via
>> conda. Obviously it will be even better when scipy wheels are
>> available, but incremental progress is still progress :-)
>>
>> I guess the one downside is that right now, if someone who is missing
>> the crucial things tries to do 'pip install scikit-image' then your
>> setup.py can give a nice error message explaining, whereas if a
>> scikit-image wheel is available then that person will still be doomed,
>> but may not get as nice an error message telling them so. (I.e.,
>> they'll get whatever error message you get when you try to do 'pip
>> install scipy' on Windows.)
>>
>
> One other thing to improve things for users is to change the scikit-image
> install instructions.
>
> It should start with pointing to Anaconda/Canopy/WinPython, and explaining
> that that's definitely the better option for users (rather than pip) at
> this point in time.
>
> Then, http://scikit-image.org/download says to use ``pip install -U
> scikit-image``, which is never the right command - it will attempt to
> upgrade numpy and scipy. Remove the -U or add --no-deps.
>
> Ralf
>
>
>
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