Coding advice

• Think about how to cleanly structure your code. Take a similar approach to how we write papers and grants.

• Break the overall problem into pieces, and then decide how to structure each piece in turn.

• Divide your code into functions that each do one "thing", and group related functions into separate files or modules.

• It can sometimes help to think about how you want the final code to look, and then design the functions and components that are needed.

• Avoid global variables, aim to pass everything as function arguments. This makes the code more robust and easier to run.

• Avoid passing lots of individual parameters as separate arguments, this is prone to error — you might not pass them in the correct order. Instead, collect the parameters into a single structure (e.g, a Python dictionary, an R named list).

• Avoid making multiple copies of a model if you want to change some aspect of its behaviour. Instead, add a new model parameter that enables/disables this new behaviour. This allows you to use the same code to run the older and newer versions of the model.

• Try to collect common or related tasks into a single script, and allow the user to select which task(s) to run, rather than creating many scripts that perform very similar tasks.

• Write test cases to check key model properties.

  • You want to identify problems and mistakes as soon as possible!

  • Thinking about how to make your code testable can help you improve its structure!

  • Well-written tests can also demonstrate how to use your code!