filter attribute

The filter command specifies the conditions in which data should be recorded.

Member of

Syntax

/ filter = [expression; expression; expression; ...]

Parameters

expression

Specifies a expression returning true or false determining whether data should be recorded.

Remarks

The filter command enables a script to dynamically determine which rows of data should be recorded by a data, datastream, or eyetracker element. This is especially useful for continuous data streams such as datastream and eyetracker where many rows of data are written per second and data files can grow quite large. The filter can reduce the size of data files by allowing an experiment to record data only when the relevant conditions are met.

Examples

The following datastream records data only if the specified video is playing:

<datastream example>
/ columns = (date, time, subject, video.test.currenttime, response)
/ filter = [video.test.isplaying]
</datastream>