Feature: supply filter for eye movement data

[jodeleeuw]

Suggestion from a colleague:

One thing that could be useful is to have the ability to categorize something as a “fixation.” In Eyelink systems for instance, you can choose to only collect or output fixations and saccades as opposed to every single sample. This can reduce file size quite a bit and it’s usually what people want to analyze anyway. I don’t remember what Eyelink’s criteria are but it has some algorithm for classifying a sequence of samples as a fixation.

I think providing a generic filter interface and supplying a built-in fixation filter would be a great thing to include.