asv benchmarks for imports and tools modules

[sfmig]

A suite of asv benchmarks for timing the main imports of the package and several functions from the tools module. Benchmarks are defined as methods of a class, with common setup and teardown functions.

Basic usage

• First, install asv in the desired environment: pip install asv
• To run all benchmarks locally, navigate to the directory where the asv config file is (cellfinder-core/benchmarks/asv.conf.json) and execute: asv run
• To run a subset of benchmarks (e.g., the tensorflow prep benchmarks): asv run --bench tools.prep.PrepTF
• The results will be saved in a newly created benchmarks/results directory as json files. These can be visualised in a static web site by running first asv publish and then asv preview.

For further details on usage and useful commands, see the benchmarks/README.md file.

Structure

The structure follows the approach from the astropy-benchmarks repo, in which the benchmarks modules roughly mimic the package modules. The numpy benchmarks follow a slightly different structure but it is also a useful reference.

mypy fixes

To avoid mypy errors:

• I added one of the benchmarks file to the mypy exclude section in the pre-commit config, and
• added cellfinder_core.tools.prep.* to the list of modules from which ignore import errors. Not sure if this is best practice but I couldn't find a better way around it. Happy to get feedback on it!

Existing benchmarks

I moved a set of previous memory benchmarks written by @dstansby to a subdir in benchmarks called mem_benchmarks.

[adamltyson]

Thanks @sfmig!

Minor point: I wonder whether instead of putting questions for reviewers into the code itself and risking that we inadvertently merge them, should they in future be added as comments on the PR?

Yes please add all comments to the PR itself rather than in the code. And create issues rather than TODO: etc. It's a bit of a pain for the developer, but much easier for everyone else to keep track.

[alessandrofelder]

On mypy I've done some thinking and discussing with @willGraham01 (thanks!). We understood that the import errors are caused by the benchmarks code being outside the cellfinder_core folder, so mypy treats cellfinder_core like a third-party library.

I would suggest to ignore any import errors happening in benchmarks/ by excluding them in pyproject.toml (until we fix brainglobe/cellfinder#278 which is not high-priority).