Package issue: scipy

[stumpylog]

Package name

scipy

Package version

1.9.0+

PyPI URL

https://pypi.org/project/scipy/

piwheels URL

https://www.piwheels.org/project/scipy/

Python version

• [X] Python 3.5
• [X] Python 3.7
• [X] Python 3.9

I am the maintainer

• [ ] Yes

More information

With scipy 1.9.0, the default build now expects OpenBLAS (see https://scipy.github.io/devdocs/release.1.9.0.html). The probably quick way to get it building is include libopenblas-dev, though this would change the install instructions too.

Otherwise, it looks like some build time options can be set to choose: https://scipy.github.io/devdocs/dev/contributor/meson_advanced.html#blas-lapack-selection

[bennuttall]

We currently have libblas-dev installed. Is it safe to run both libblas and libopenblas together, or might that cause issues? @waveform80

[stumpylog]

I think the better solution would be keeping the package linked against libblas, at least for now. I could see an upgrade happening, but without the new libopenblas installed and that causing people all sort of troubles.

I believe the build command would need to be something like: python -m build -C-Dblas=blas -C-Dlapack=lapack

[rgommers]

There is no need to change BLAS libraries indeed, and you don't want to run two different ones together. So I suggest keeping it unchanged. The build command should then be:

python -m build -Csetup-args=-Dblas=blas -Csetup-args=-Dlapack=lapack

or, if you need build isolation:

python -m build -Csetup-args=-Dblas=blas -Csetup-args=-Dlapack=lapack --no-isolation --skip-dependency-check

pip unfortunately doesn't yet support passing the same key (setup-args) to --config-settings twice, so build has to be used instead of pip.

I don't have a Raspberry Pi, but am interested in helping here if I can (I'm the SciPy build system maintainer). That will also help fix the SciPy build issue I just cross-linked with missing libatomic, which seems specific to armv7 / Raspberry Pi. It looks like there's no building in regular CI on the piwheels repo, so probably not useful for me to make a PR there?

[bennuttall]

We don't run python -m build, we use pip wheel.

[rgommers]

Hmm, that's a problem, pip wheel doesn't handle specifying both blas and lapack, I don't see a good way around that right now with --config-settings. If you can apply a patch, then it's easy enough:

diff --git a/meson_options.txt b/meson_options.txt
index 5935bb850..f8c14ce46 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -1,6 +1,6 @@
-option('blas', type: 'string', value: 'openblas',
+option('blas', type: 'string', value: 'blas',
         description: 'option for BLAS library switching')
-option('lapack', type: 'string', value: 'openblas',
+option('lapack', type: 'string', value: 'lapack',
         description: 'option for LAPACK library switching')
 option('use-g77-abi', type: 'boolean', value: 'false',
         description: 'If set to true, forces using g77 compatibility wrappers ' +

Then pip wheel . should work out of the box.

[eli-schwartz]

We don't run python -m build, we use pip wheel.

There's no meaningful difference there aside for the fact that pip gives you less control, as it was never meant to be a scripting tool...

[stumpylog]

Given the package is now a couple of versions behind, perhaps it would be time to provide the default expected dependencies and update the install instructions of the page?

I think it would only require including OpenBLAS (libopenblas-dev) on the builder.