Creating Experiments with Python and Neuropsydia

Part 2.1: Structuring your Code

Dominique Makowski

This course is supported by the École de Neuropsychologie group.

---

About the course

Course Status
Length	≈ 15min

Contact

For remarks, complaints, suggestions or anything else, please create an issue.

Intro

General Principles

There are actually many ways to do it. Each person has its coding style. Here, and throughout all tutorials, we will strive to write a clear, neat, organized, structured, and reproducible code. Basically, we won't write 1000 linear lines of procedure, we will rather create several blocks of code which we will then assemble.

A code lacking structure is called spaguettti code. When beginning with programming, you usually end up writing this kind of code anyway. Later on, you learn to structure it.

And remember, a clear code is a clear thought: you can then make adjustment and correct bugs much more easily.

To take an abstract example, imagine an experiment when we present images in two conditions, "negative" and "positive", and ask the participants to rate each image on a scale of Fear, Anger and Joy. You experiment code might look like this:

condition="negative"
image("negative1.png")
ask("Fear?")
ask("Anger?")
ask("Joy?")

condition="positive"
image("positive1.png")
ask("Fear?")
ask("Anger?")
ask("Joy?")

condition="negative"
image("negative2.png")
ask("Fear?")
ask("Anger?")
ask("Joy?")

condition="positive"
image("positive2.png")
ask("Fear?")
ask("Anger?")
ask("Joy?")

...

If you have like 100 trials, your code will start becomming quite indigest. What can we do to make it more neat? First, we see that the three ask() functions are very redundant. a first step would be to regroup in a unique function that we will define at the beginning and call evaluation.

def evaluation():
    ask("Fear?")
    ask("Anger?")
    ask("Joy?")

The rest of the code would then look like this:

condition="negative"
image("negative1.png")
evaluation()

condition="positive"
image("positive1.png")
evaluation()

condition="negative"
image("negative2.png")
evaluation()

condition="positive"
image("positive2.png")
evaluation()

...