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OpenSCM-Calibration-examples

Long-running examples using OpenSCM-Calibration.

Installation

After cloning the repository, we recommend installing with poetry.

poetry install

Running the examples

All the examples can be run with (and the docs built with)

poetry run jupyter-book build book

Rationale

As a user of OpenSCM-Calibration (or indeed any repository), it is helpful to have examples of how it is used in production and the outputs it produces. However, including such examples in the core development repository comes with a problem: it adds a very slow step to any continuous integration, which quickly becomes really annoying for development. A secondary problem is that you also end up with output in the repository, which quickly bloats it (even notebooks can be megabytes in size if they contain many plots).

The solution we use here is to house our production-style examples in a separate repository. We don't run these examples every time we change the code base, however we do run them regularly and check/update them when the core repository makes new releases.

Further details

Even in this repository, we don't currently store outputs in the notebooks. The reason is that outputs can quickly become bloated and storing the outputs discourages re-running i.e. testing the notebooks.

Having looked around, we haven't found a good solution that allows us to run our notebooks once as part of a test, then use the run output directly in a docs build without rebuilding. nbmake claims to support this use case, but in our experience jupyter-book didn't recognise the nbmake output and tried to re-run the notebooks anyway. Perhaps we were just using the combination of tools like nbmake, jupyter-cache and jupyter-book incorrectly (one thing to keep in mind if trying to make this work is that we want the execution time of the notebook to appear in our docs too).

Instead, we combine the docs building and testing steps. We build the docs using jupyter-book, and include, in our notebooks, assertion cells that act effectively as tests. We avoid polluting the entire notebook with these assertions by making them hidden by default (and use jupyter-book's support for showing and hiding cells to give users and readers the chance to check them if they wish). We like this solution because it makes clear to developers where the assertion is (other solutions hide the assertions in the cell's JSON, which feels like a hack to us) and allows users to look at it if they wish while making clear that they aren't actually necessary for the example to run.

We do check the notebook formatting as a separate step. This is easy to do and very cheap using blacken-docs.

Really long-running notebooks

If we want to add super long-running notebooks to this repository, one possible problem is that they are too long-running to reasonably run in CI (perhaps they take 3 days to run). In this case, one solution could be to start tracking some of the outputs of our notebook cache. This would make the notebook untested in most cases (because the cache would be used instead of running the notebook) but this might be the best compromise where running the notebook is truly not an option. We don't have such a use case yet so we haven't implemented this, but we think the current solution doesn't shut the door on really long-running notebooks so is a good choice for now.

For developers

For development, we rely on poetry for all our dependency management. For all of work, we use our Makefile. You can read the instructions out and run the commands by hand if you wish, but we generally discourage this because it can be error prone and doesn't update if dependencies change (e.g. the environment is updated). In order to create your environment, run make virtual-environment -B.

If there are any issues, the messages from the Makefile should guide you through. If not, please raise an issue in the issue tracker.