StimulusContainer class

Maintain several stimuli, and can present them all with a single command. You can also define some of the stimuli as temporarily invisible by setting their “visible” property.

Using this class

• Create the container
• Add visual objects to the container using add()
• Once an object is added to the container, it will have a “visible” property, which you can set at any time.
• Present the container using present() . All objects with visible=True will be presented.
• Objects added to the container later will appear on top of earlier-added objects.
• You can access objects from the container by writing container[obj_id], where obj_id is the ID you provided to add().
• You can also tell the StimulusContainer to call a function when present() is called - to do this, use register_callback()

Methods and properties:

class trajtracker.stimuli.StimulusContainer(name=None)

__init__(name=None)

Constructor

Parameters:name – A name that identifies this container (this is used only to print in log messages)

add(stimulus, stimulus_id=None, visible=True)

Add a stimulus to the container.

Parameters:

• stimulus – An Expyriment stimulus, or any other object that has a similar present() method
• stimulus_id – Stimulus name. Use it later to set the stimulus as visible/invisible. If not provided or None, an arbitrary ID will be generated.
• visible – See The stimulus ID (as defined in set_visible())

Returns:

log_level

Logging level of this object: trajtracker.log_none, log_error (default), log_warn, log_info, log_debug, log_trace

offset_event

The time when the object should disappear from screen.

Type:Event, or None to avoid automatic offset.

onset_event

The time when the object should appear on screen.

Type:Event, or None to avoid automatic onset.

present(clear=True, update=True)

Present all visible stimuli in the container Stimuli marked as invisible will not be shown

Parameters:

• clear – See in Expyriment <http://docs.expyriment.org/expyriment.stimuli.Rectangle.html#expyriment.stimuli.Rectangle.present>
• update – See in Expyriment <http://docs.expyriment.org/expyriment.stimuli.Rectangle.html#expyriment.stimuli.Rectangle.present>

Returns:

The duration (in seconds) this function took to run

register_callback(callback_func, recurring=False, func_id=None)

Register a “present callback” - a function that should be called when the StimulusContainer is present()ed

Parameters:

• callback_func –

  A function or another callable object, which will be called. This function takes these arguments -

  1. The StimulusContainer object
  2. a tuple with the IDs of the stimuli that were actually presented (i.e., stimuli that had stim.visible == True)
  3. The time when present() returned
• recurring – True = invoke the function on each present() call. False = Invoke the function only on the next present(), and then forget this function.
• func_id – A logical ID for a recurring function (it can be used to unregister the function later)

remove(stimulus_id)

Remove a stimulus from the container

Parameters:stimulus_id – The ID to remove Returns:True if removed, False if not found

unregister_non_recurring_callbacks()

Clear all non-recurring listeners that were previously registered

unregister_recurring_callback(func_id)

Unregister a recurring listener function that was previously registered via register_callback()

Parameters:func_id – The function ID that was provided to register_callback() Returns:True if unregistered, False if there is no registered recurring function with the given func_id