Python 3.13 preparation

[mikofski]

Is your feature request related to a problem? Please describe.
Final release candidate of Python 3.13 announced. Requests upstream for prep

Describe the solution you'd like
As Python 3.13 to test matrix similar to RdTools

Describe alternatives you've considered
Put upper bound on Python compatibility

Additional context
See Google group discussion on py3.13rc02.

[kandersolar]

@RDaxini or @IoannisSifnaios, any interest in continuous integration (CI) infrastructure management? Adding python 3.13 to the test matrix would be a good way to dip your toes into that world :)

Note that we can't start testing on 3.13 just yet since some of pvlib's dependencies (e.g. h5py) haven't released wheels for it yet. So Step 0 here is just to check in on the dependencies every once in a while. Once those wheels are available, we'll modify the GitHub Actions workflow files to include 3.13. See #1886 for an example of what that looks like.

[RDaxini]

@kandersolar Sure I am interested.

I was reviewing #1886 as advised and I noticed here that although some of the dependencies were unavailable in python 3.12, e.g. numba, this does not seem to have been a problem(?) ---why not?

This is not something with which I have any experience so I might just be missing/misunderstanding something obvious 😅

[kandersolar]

It's a good question! The reason is that some of pvlib's dependencies are required while others are merely optional. "Required" means that pip install pvlib will fail if pip can't locate a suitable installation file for the dependency. "Optional" ones are not required for installation to succeed, but of course some pvlib functionality is not available unless the relevant dependency is installed. Our tests are configured such that tests for that functionality get skipped if the relevant optional dependency isn't installed.

You can check that the dependencies omitted in #1886 are all optional dependencies as defined in pyproject.toml:

pvlib-python/pyproject.toml

Lines 13 to 20 in a14e95e

	dependencies = [
	'numpy >= 1.17.3',
	'pandas >= 1.3.0',
	'pytz',
	'requests',
	'scipy >= 1.6.0',
	'h5py',
	]

pvlib-python/pyproject.toml

Lines 48 to 56 in a14e95e

	[project.optional-dependencies]
	optional = [
	'cython',
	'ephem',
	'nrel-pysam',
	'numba >= 0.17.0',
	'solarfactors',
	'statsmodels',
	]

And just to finish the story, we did add those dependencies back in once wheels became available: #1964

[IoannisSifnaios]

@kandersolar is there an easy way of finding which optional dependencies do not work with python 3.13? E.g., if we make a PR, would we get an error about which ones are not compatible? Or do we have to manually check each one of them to see if it is 3.13 compatible or not?

[kandersolar]

Yes a PR would certainly tell you whether the package landscape is sufficiently progressed for us to start using it for pvlib. I suppose there is no harm in opening a PR now, with the expectation that it will remain open for some time waiting for the dependencies to become available. In fact the current roadblock may be whether python 3.13 itself is installable on the CI yet :P

[echedey-ls]

We need to bring back the discussion of solarfactors again pvlib/solarfactors#16
There will certainly be problems with all the code that relies on solarfactors.

[IoannisSifnaios]

Yes a PR would certainly tell you whether the package landscape is sufficiently progressed for us to start using it for pvlib. I suppose there is no harm in opening a PR now, with the expectation that it will remain open for some time waiting for the dependencies to become available. In fact the current roadblock may be whether python 3.13 itself is installable on the CI yet :P

Makes sense! I guess we should at least wait for the official release (1/10/2024)

[markcampanelli]

I will ask again: Please start putting upper bounds on the Python versions supported in the pyproject.toml.

python -m pip install -e .[all] is simply broken ATM on Python 3.13.0.

If I update the pyproject.toml to clearly state requires-python = ">=3.9, <3.13", then I get a very clear and actionable error message:

ERROR: Package 'pvlib' requires a different Python: 3.13.0 not in '<3.13,>=3.9'

[markcampanelli]

A more granular way to handle this so that optional dependencies don't hold users back is:

[project.optional-dependencies]
optional = [
    'cython',
    'ephem',
    'nrel-pysam;python_version<"3.13"',
    'numba >= 0.17.0;python_version<"3.13"',
    'solarfactors;python_version<"3.12"',
    'statsmodels',
]

Note that solarfactors also shows up in the doc section , and I don't know if the upper exclusion limits here may actually be lower than 3.13 .

All that said, please still use requires-python = ">=3.9, <3.13" until pvlib is actually being built and tested in CI on Python 3.13.

UPDATED: solarfactors apparently requires Python <3.12, which I updated here.